TalkHunting Community

Tools of the Trade => Firearms => Topic started by: MI_Bowhunter on February 10, 2017, 09:29:03 AM

Title: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on February 10, 2017, 09:29:03 AM
Well, I finally decided to pull the trigger and buy a barrel and bolt in 450 Bushmaster. I'm going to be building a hunting gunaround it and trying to keep it fairly low budget.

Barrel and bolt should arrive next week and the real fun will begin.

I did not spend the extra $$ on a 450BM receiver so there will be a little machining to open up the ejection port for the larger brass.

Power tools and guns, what could possibly go wrong?

For those unfamiliar with AR-15 assembly I'll post pics as I go. Feel free to ask any questions you have

Might even mill out an 80% receiver just to make it even more interesting!!

Buckle up, this is going to be fun!
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on February 10, 2017, 01:57:06 PM
Looking forward to see what you come up with.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on February 10, 2017, 03:42:35 PM
Looking forward to see what you come up with.
Me too!!   LOL
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on February 10, 2017, 04:26:20 PM
Great, give us the step by step build. I'd love to do the same, but don't think I have the tools for it ()*$%RT
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on February 10, 2017, 04:52:47 PM
sounds like you are getting ready for our pig-o-rama
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on February 10, 2017, 07:01:34 PM
MI-B - I'm definitely interested in hearing more as you go forward with this.  Have been thinking about building up a big-bore thumper but haven't pulled the trigger on it yet (have two new stripped lowers & uppers just waiting to be built up though).  Will be curious to see what you need to do on the ejection port - are you diving in to that by trial & error, or have you found some good guidance on it?  One of my stripped uppers is a slick-side with no forward assist boss or dust cover mounting - that might be the place for me to start on one of these builds.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on February 10, 2017, 07:47:48 PM
Great, give us the step by step build. I'd love to do the same, but don't think I have the tools for it ()*$%RT

The only specialized tool you need is a barrel nut wrench and they are available pretty much anywhere ARparts are sold.   Some hand guards require a special wrench but the majority will use the std tool.  Everything else can be done with std home tools.

sounds like you are getting ready for our pig-o-rama

It will definitely work for that.   My primary intended use is for deer.   The lower half of lower MI is designated a shotgun only zone for deer hunting (some pistol calibers and muzzle loader are allowed).  A couple years ago they expanded it to allow certain straight walled cartridges to be used in rifle form.  My primary hunting location when I hunt in this area is over a corn/bean field.    This will extend my range a bit over a shotgun or my muzzleloader. (Plus it's just fun to put together guns  ;D )

MI-B - I'm definitely interested in hearing more as you go forward with this.  Have been thinking about building up a big-bore thumper but haven't pulled the trigger on it yet (have two new stripped lowers & uppers just waiting to be built up though).  Will be curious to see what you need to do on the ejection port - are you diving in to that by trial & error, or have you found some good guidance on it?  One of my stripped uppers is a slick-side with no forward assist boss or dust cover mounting - that might be the place for me to start on one of these builds.

I've been doing some research and lurking on a 450BM specific forum and have picked up a lot.   The port needs to be opened up a small amount along the lower edge and a little along the top towards the rear.   If you wish to continue using the dust cover you have to careful not to remove the material where it latches.   I orderred my barrel, bolt (not including carrier) and thread protector from Tromix Lead Delivery Solutions.    They also sell stripped uppers,( already modified), gas block, compensator, etc as well as complete uppers.   They wanted $135 for a 450BM upper, my Anderson cost $44.  I've rather save the money or apply it elsewhere where it I will get more out of it such as trigger.

As this will likely be shot from a ground blind I opted to go without a comp.  Yes they reduce recoil but they are also LOUD, esp where the sounds can bounce off a nearby wall, etc.   I doubt the recoil without it will be much more than a small shotgun so I am not too concerned about recoil on this one.

I already have a carrier for the bolt, scope, charging handle and a extra completed lower so that eliminated a lot of expense right off the top. To spice it up I may finish off a 80% lower I have had sitting here for a while.  This is an aluminum lower and I have the jig and machine bits to finish it with a router.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on February 11, 2017, 08:03:21 AM
MI - Great build, always had respect for the 450 Bushmaster! One great bear rifle....and deer and almost anything else you might want to take with it would make a pretty darn good home defense round as well...LOL...

Keep us all informed of your progress...should be an interesting build...
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on February 12, 2017, 08:54:48 PM
The parts I needed to complete the upper arrived on Saturday.  I'll start posting some pics tomorrow and get this thing rolling.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on February 13, 2017, 01:30:34 PM

How is the recoil with the 450BM?  This is new to me. 

I considered building a 6.8 or .308 before I settled on .300 AAC.
I purchased pretty much barrel and complete upper to make it an easy swap and ended up with all the tools necessary for my next build.                                                   ()*$%RT                 ()*$%RT                       ()*$%RT                ()*$%RT
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on February 13, 2017, 02:45:52 PM

How is the recoil with the 450BM?  This is new to me. 

I considered building a 6.8 or .308 before I settled on .300 AAC.
I purchased pretty much barrel and complete upper to make it an easy swap and ended up with all the tools necessary for my next build.                                                   ()*$%RT                 ()*$%RT                       ()*$%RT                ()*$%RT
I'll let you know when I finish it. I have honestly never shot one.  From what I have been told, the recoil is approximate to a 20g shotgun. That really doesnt tell me much but I figure it has to be less than that of a 12g slug. LOL
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on February 13, 2017, 04:05:25 PM
Sounds great!! keep us posted  as you go sounds very interesting.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on February 13, 2017, 05:27:15 PM
wish we could that in new York state but noooooooooo
 
 @--0--0101     (*&^&%# 
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on February 13, 2017, 05:49:52 PM
OK Here are some pics:

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_001_zpsf7f8nfaz.jpg)

All the parts laid out.   Some I just bought, some I already had.    I reserve the right to change up any of these as I go.   ;D

The gun in the background is my 300BLK that I built a while back.

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_002_zpspqb2fakl.jpg)

Matrix Arms Keymod Handguard.  This is a friction fir free floating tube.   The barrel nut that comes with it is different than any I gave seen.  I will have to find some other way to torque this one down.  It has flats on four sides, I have not determined size yet.

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_003_zpsceuhchxz.jpg)

Barrel stamp.  I was impressed that this barrel already has a detente hole under the gas port.  I will add a second but this is the first I have seen to come with one.    I will expand on this later in the build.

Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on February 13, 2017, 05:57:20 PM
(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_004_zpsxdq0h2kq.jpg)

Looks like they took a std M4 barrel extension and ground it down to make the 450 feed ramp.

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_005_zpszlaqmp5p.jpg)

Here I just laid everything together to give you an idea how it will look when it is done.   Not really assembled but enough to see what it will look like.

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_006_zpsfr0pm6no.jpg)

Closer look.

There really is not much to putting together an upper.  This one is only made more difficult because I need to mill out some of the metal around the ejection port for the larger 450BM brass.

Next I'll take it all apart and go through the details of assembling it for real.   I am still trying to figure out exactly how I want to tackle opening up the ejection port.   Look to borrow a cross slide vise I can can be more precise in milling away the metal.  I'll keep you posted.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on February 13, 2017, 06:09:19 PM
I'm not into those rifles, yet ##$%#1119.

I have a brother-in-law that has been making those up for several years. He surprised me by saying he had to do a little bit of machine work on the upper/lower?  "You got a milling machine, Bro?" He says, "Naw, I've got a jig, kinda' like a router bit that I work with."  He's having fun, I've fired one of his creations, it was nice but I still think "Mattel Toy" when I see one.  Old Corps creeping out, M-14 with Walnut stock or a blue steel and wood 700 :).

The other evening there was an article on the news about the "Ghost Rifles" being made in the US, no serial numbers to trace them from the hands of the criminals who make and supply them to the youth of our nation.  They reported the weapons were fully automatic and then went on to show a person firing an AK @--0--0117.  What a bunch of crap!!!

Thankfully in Florida we still are not hindered by state laws that prohibit us from building such a rifle.  Most of the Florida politicians that clamor for gun control are transplants from states that have very restrictive gun laws.  It seems they escape the cold and come to Florida to straighten us Cracker rednecks out and to make life as miserable as it was in the big cities they came from!  (I'll get down off my soap box, now.)

Back on topic, MI_Bowhunter, glad you are going to do this as a tutorial and I for one will be very interested.  There's probably hope for me, a few years ago I was 100% wheelgun and now I carry a polymer/plastic sand colored thing everyday.
Treefarmer     
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on February 13, 2017, 08:05:25 PM



The other evening there was an article on the news about the "Ghost Rifles" being made in the US, no serial numbers to trace them from the hands of the criminals who make and supply them to the youth of our nation.  They reported the weapons were fully automatic and then went on to show a person firing an AK @--0--0117.  What a bunch of crap!!!
 

They are making a bigger deal of it than it is. How many average criminals are gojng to buy an 80% receiver, buy a jig, mill it out, buy parts kit, buffer tube, bolt, etc and assemble it so they can use it in a crime. The average criminal is going to take the easiest route possible and use whatever they can buy on the street or steal. Hollywood has distorted peoples sense or reality.

You can finish a polymer lower without a jig using only a dremmel but you have to be spot on to end up with somethjng that will work. If you are off by even a little the trigger parts will not line up and function correctly. Good luck with that, its not easy without a jig.

I was slow to jump on the black rifle bandwagon as well but I have to say that it becomes an addiction. You can tweak, customize and reconfigure them as much as you want to make it fit what you want. They are the most versatile firearm system created to date.

Come to the dark side!!!!  LOL





Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on February 13, 2017, 08:44:40 PM
Yeah - the whole "ghost guns" bit seems to be the latest thing for the media fanatics to sink their teeth into - one more opportunity for them to make crap up that gets everyone's undies in a knot.  A year or two they were trying to convince the world that 3D printers were going to cause the streets to be flooded with homemade guns . . . heck if I thought I could actually make a functional gun on a 3D printer I'd probably own one by now (the printer that is).

MI-B - I'm in about the same boat as you - have been playing with the black guns for about 3 and a half years now - preparing to build #4.  I was looking at buying one of those Matrix handguards you have - didn't realize that was what their barrel nut looked like.  If it's just those 4 wrench flats on it (no spanner holes?) can you put a crowfoot on your torque wrench to tighten it down?  That ramp in the barrel extension is interesting - looks like they just cut it in right on top of the regular M4 ramps.  I have 2 stripped uppers & 2 stripped lowers to build out - still need to buy barrels, stocks, handguards, etc.  Think I will build one out with wood furniture and a 20" barrel, make it look like an A2 but with a flat top upper & folding rear sight.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on February 14, 2017, 08:28:56 AM

MI-B - I'm in about the same boat as you - have been playing with the black guns for about 3 and a half years now - preparing to build #4.  I was looking at buying one of those Matrix handguards you have - didn't realize that was what their barrel nut looked like.  If it's just those 4 wrench flats on it (no spanner holes?) can you put a crowfoot on your torque wrench to tighten it down? 

A  crow foot is what I had thought as well. According to online specs its a 1 3/16" but some have said a 30mm wrench worked fine.  Being flat on four sides there is a little more flat area to work with so either would probably work. I need to make a trip to the auto parts store to get one. I bad intended to grab the nut on the way out this morning but forgot it.  I kind of like the design, you do not have to worry about having to over/under torque the nut to get the gas tube holes to line up.

The Matrix arms handguard is small. I'll have to measure but it is noticibley smaller in diameter than my other handguards, even those without rails.  I do not think that will be a bad thing in this build as being leaner and lighter is good in a hunting gun you may have to lug around. AR's can get heavy as they tend to have a lot of excess rails and whatnot that you may not need for the specific task.  We'll see but I think I am going to like this handguard.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on February 23, 2017, 10:10:28 AM
Tree and others, I have gone through my phases of rifles design, first it was a heavy barrel, (Still get those for sure) then it was a single shot type rifle, such as the Ruger No.1, put followers in on some of my regular bolt action rifles to make them a single shot...bought a few Remington single shot 40X style rifles, then purchase a use Shilen DGA rifle, and then purchase the Coopers single shot rifles....

And now, and now, have gotten into the Black or AR rifles...built a few, just to learn about them and have a few built, bought some uppers and now own all of them a 300AAC, 6.5 Grendel, 6.8 SPC II, one AR15 with Shilen upper with night vision capabilities. I also have a red dot scope in the case just in case.....But the AR style rifles are great!!! You are seeing them more and more on the hunting shows..just saw one the other day on antelope hunting!! My first AR style rifle was a plain jane Colt A2 from my bother in law and the second was a Rock River 223 with a 24 inch barrel for the long range varmint hunting, should have gotten a 20 incher...then I went quiet for a while, but always keeping my eyeball on the AR style rifle....

But they are hear to stay!!! Tree - jump into the AR Arena and learn as you go as I did and still am learning about them

thanks for all the pictures on your build...now just post the game you take with it....maybe there should be a separate section on TH for the AR style rifles ?? What do yawl think ??

I love mine AR's and only use 10 round magazines at the range, and save the 20 and 30 round magazine for hunting (any kind of hunting!!!)......

I have several 22-250 in my collection all of them shoot dime groups at 200 to 250 yards and treat them as my fastest and flattest round, Dutch as most of you know is speed (Freak??) person where a 4000 fps is his bench mark of a rifle...LOL...but these days also keep my 223 away from my 22-250...but now have my eye on the 22 Nosler...have been reading several good reports on them and reviewing the ballistics on this little monster...I cannot imagine a AR style round having the almost same velocity as a 22-250, to me, this is just mind blowing...but don't get me wrong, will buy one in a heartbeat when they get the bugs worked out...cannot imagine taking a coyote at 300 and 400 yards with any AR style rifle....
 
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 05, 2017, 04:07:43 PM
OK, got my upper milled out.

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_MilledUpper_000_zpstsnr1yrn.jpg)

My High tech milling machine.    Craftsman Drill Press, cross slide vise, 1/4" end mill bit and a bunch of c clamps

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_MilledUpper_001_zpshq0ek06p.jpg)

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_MilledUpper_003_zpshn7qkbji.jpg)

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_MilledUpper_002_zpsnijsivea.jpg)

Before painting I will file down the sharp areas (i.e. where I ended the cut near the dust door catch)

https://www.youtube.com/watch?v=nS1rR5EAhbI&feature=youtu.be (https://www.youtube.com/watch?v=nS1rR5EAhbI&feature=youtu.be)

My apologies on the poor focus in some parts of the video, I forget that my DSLR does not autofocus in video mode.  I did not realize my error until I was done and downloaded the video to edit it.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 05, 2017, 09:18:13 PM
MI-B - Thanks for the pix and video, well done!  Did you really need to take any material at all from the front vertical edge of the port, or just the top and bottom edges? 
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 05, 2017, 09:31:17 PM
It was uneccesary and unitentional to remove any material forward of the the barrel extension.  I trimmed a little because I had inadvertantly cut more in that direction than I intended and in trying to even it out I took too much off. If I do another I will know not to cut in that direction.

If anyone wants to build one I'll be bappy to open the port up for you, without exposing so much of the barrel extension. ;-D
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 06, 2017, 05:24:41 AM
MI - Thanks for the update.....
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 06, 2017, 07:43:35 AM
I was going to rattle can camo this one but decided to break down and buy some Cerakote for the base layer.  The camo will be be done with rattlecans. I cannot afford 4-5 colors or Cerakote. LOL

Thats going to add a little more time to the project but I'm really not in any hurry with this one and I think the end result will be better this way.

I think my next step will probably be 80% lower as long as I am taking the Cerakote route
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 06, 2017, 10:19:18 AM
Mike, check out this link.   

http://www.primaryarms.com/anderson-manufacturing-ar-15-stripped-lower-receiver-closed-ear-ar-15-a3-lwfor-um-closed
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 06, 2017, 02:23:42 PM
Mike, check out this link.   

http://www.primaryarms.com/anderson-manufacturing-ar-15-stripped-lower-receiver-closed-ear-ar-15-a3-lwfor-um-closed
The last 3 lowers I have assembled have been Andersons, one is still sitting unattached in my safe.  The upper I just milled was also an Anderson.  I already have an undisclosed number of 80%'ers that have just been begging to be completed.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 06, 2017, 05:22:54 PM
You're way ahead of me, I thought you still had to get a lower.  For $49.99 for a finished lower doesn't sound too bad, except you have to go through an FFL. 
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 06, 2017, 06:05:32 PM
$50 for a finished lower is a pretty good price Louie - you generally need to buy a fair quantity to get below that mark.  The Trump factor (and the general blasting of the liberals in November's election) has really driven prices and availability in a favorable direction. 

I've considered trying one of those 80% lowers, but for now time is more hard to come by than cash, so I'll keep building with my finished parts.  Did one with a S&W lower, one Rock River, and the rest are Andersons.  Can't say that I've been disappointed in the Andersons, and their prices are considerably lower so I'll keep on that path for now.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 10, 2017, 07:00:04 AM
I think I paid $59 or thereabouts for my Anderson lowers a while back. I got a little deal on FFL costs because I ordered several.

The Cerakote came in this week.  The process takes a fair amount of time so I want to get a few items ready. Plan on milling a lower this weekend.

I may or may not get through the painting process this weekend as well. Lots of prep involved and need to find a different method of baking than I used last time. Want to test out a small elec smoker thats been sitting in the garage for a while to see how well it can maintain temp
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 10, 2017, 07:22:13 AM
Haven't read much about the cerakote, but how long do you have to bake the stuff?  I know for powder coating cast bullets, you have to maintain 400 deg for 15-20 minutes, or at least till you see the powder coating turn shiny. 
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 10, 2017, 07:32:17 AM
Haven't read much about the cerakote, but how long do you have to bake the stuff?  I know for powder coating cast bullets, you have to maintain 400 deg for 15-20 minutes, or at least till you see the powder coating turn shiny.
Normal time is 2 hours at 250deg or if you must hurry the process you can do a fast cure at 300deg for 45 minutes.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 11, 2017, 05:57:44 PM
(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_010_zps5h6bgu0f.jpg)

Started working on my 80% lower today

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_011_zpsq90c63rg.jpg)

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_012_zpsua7uk7wr.jpg)

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_013_zpsny7vbcih.jpg)

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_014_zps9nwr5bc9.jpg)

These are the side pates for the jig. The upper screws go thropugh the take down pin holes.

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_015_zpsiqvywswx.jpg)

This is the jig used to drill holes down through the main and rear pocket.

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_016_zpsw2jvevpf.jpg)

These are the templates for the main pocket, rear pocket and trigger hole.  They also have the depth gauge for the holes as well as the mill bit.

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_017_zps9bi4ngef.jpg)

Holes drilled into lower using jig.  These holes help facilitate the milling process.  I had a heck of a time drilling these holes.  I am  not used to working with aluminum but I went through 2 drill bits and it took a long time to drill these holes.

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_018_zpsbfxrxx99.jpg)

Jig set up for milling the main pocket.

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_019_zpssvgozmfx.jpg)

The large top plate gives some surface for the router to sit stable.

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_020_zpslnbwxfdq.jpg)

Router set up and ready to start.

I am a little disappointed.  I only milled down about 1/4 of an inch before the bit stopped cutting.   I'm not sure If I was trying to take to much each pass or if I was just going to fast but I got to a point where it just bounced around and would not cut anything.

Between the problems I had drilling the holes and the issues with the mill I can say that this process is not as easy as they make it look in the video.



Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 12, 2017, 12:59:21 AM
I was letting the bit get to hot and it got clogged up with aluminum.  I cleaned it out and was able to continue on.I found I was trying to take too much off in each pass.     My router has a dial gauge that allows pretty precise adjustment to the bit depth. I ended up dropping the bit 1/32 each pass after I got the bit cleaned out and it worked really good.   It took a while but it cut clean and it greatly reduced the jumps and stutters.   I think the most difficult pass was the last as it was cutting the entire floor of the pocket as I was at the bottom of the pilot holes.

I think the problem I had drilling those holes was due to going to fast and getting the aluminum to hot.

https://www.youtube.com/watch?v=c4A-km5CqD4&feature=youtu.be (https://www.youtube.com/watch?v=c4A-km5CqD4&feature=youtu.be)

Here is a small portion of the milling process.  Darn I hate my voice on recordings, not at all how I hear myself.

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_021_zps46cfnrzb.jpg)

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_023_zps8oatwr8w.jpg)

Got the main pocket milled out.

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_024_zpsfdtcii8c.jpg)

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_025_zpsonqo2ttw.jpg)

Got the rear pocket milled out.  I did have to remove the rear screw from the jig for this, I had already reinstalled it by the time I took the picture.

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_026_zps76hoqr0e.jpg)

Drilling out the hole that will be used to start milling out the trigger opening.

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_027_zpsjgyzszlv.jpg)

Ready to mill out the trigger port.

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_028_zpsitaqtidt.jpg)

Trigger port opened up.

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_032_zpswrdfkbpe.jpg)

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_031_zpstktw33oe.jpg)

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_030_zpspflfhydp.jpg)

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_029_zps9f93cvbv.jpg)

After drilling the hold for the trigger/hammer pins and the safety lever it's all done.

Needs just a little sanding to smooth out some of the edges but as far as milling and drilling it's complete.

This was an interesting endeavor.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 12, 2017, 06:51:38 PM
Thanks for the continued reports - aluminum can certainly be finicky to machine, gotta be patient to keep from getting it hot & smeary.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 12, 2017, 07:18:41 PM
Thanks for the continued reports - aluminum can certainly be finicky to machine, gotta be patient to keep from getting it hot & smeary.
Now you tell me. LOL
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 13, 2017, 09:29:30 AM
I tried to do a bit of a function check on the lower and I am glad I did.   When the trigger is installed there is no movement whatsoever.  I will have to put it back into the jig and remove a little bit more from the floor of the main pocket.


Edit:   Measured it.   My depth should be 1.250" and I am right at 1.1945.   Just need to lock it back into the jig and fine tune it.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 13, 2017, 04:04:49 PM
Adjusted the depth so the trigger works now.  I overshot a bit this time but it still seems to function good.

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_034_zpsguvwpwhe.jpg)

(http://i86.photobucket.com/albums/k102/tradhunter/Guns/450BM/450BM_Build_035_zpspd8mk1ga.jpg)
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 13, 2017, 04:08:49 PM
Looks pretty good with that milled external finish on it - maybe just round off the corners & clear coat it?
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 13, 2017, 10:21:09 PM
Looks pretty good with that milled external finish on it - maybe just round off the corners & clear coat it?
This one will be painted but I also really like the machined look and will be making one at some point that leaves it in that state.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 14, 2017, 06:55:50 PM
I ran into some minor issues on my second build with a 100% factory lower, so have started doing basic checks on everything before I drive in the roll pins (they're too much of a pain to remove).  I use small drill bits as temporary pins to make sure everything is fitting up right, then drive in the pins.  I think you'll want to check things out carefully before you paint it in order to avoid having to come back & touch it up.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 14, 2017, 09:07:28 PM
One of my concerns if that the paint will close up the tolerances a bit.  Anything that fits quite snug now will not fit at all after a cote of Cerakote.

I have not fit test everything but the front pivot pin already fits very tight.  I will probably ream it out a tad as the paint will tighten it back up.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 15, 2017, 08:02:32 AM
Looks pretty good with that milled external finish on it - maybe just round off the corners & clear coat it?

Thinking it would go good with this upper:

Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 15, 2017, 07:45:01 PM
Yeah, I did a rattle can camo job on one of my builds.  It looks nice enough (didn't spring for Cerakote) but in hindsight there are a few things I would mask off more carefully.  The oblong hole for the mag release and the inside surfaces of the slot for the bolt release would be a couple of those.  When I did it I just closed the dust cover, put foam in the magwell and charging handle openings (left the CH black), and in the trigger opening.  I had the receiver pins installed.  Also masked off the rail to make sure I had a good metal to metal fit when I mounted sights or optics.  Given that you need to bake the Cerakote you probably won't want to have everything installed but you could mask those surfaces to avoid the paint issues (although I guess that would leave raw aluminum showing which you may not want).
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 15, 2017, 08:07:54 PM
I would like to coat the entire lower with the Cerakote.

I was watching a video where a guy got too much paint buildup around the top of the receiver when trying to get paint in the magwell and trigger pockets. His two receivers would not mate up just due to tight tolerances and excess paint layers between.

 I'm thinking of masking arount the openings then remove the tape to continue painting the outside.

This is my 2nd go around with Cerakote. I painted a shotgun a few years ago. This time I plan on using an airbrush as opposed to the HVLP spray gun I used with the previous project. I am hoping to get a little less overspray and even better control with this approach.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on March 27, 2017, 10:52:12 AM
It's been a while since I updated this but rest assured I haven't abandoned this project!!

I really do not like to paint parts when it is cold.   I also do not have a sand blasting box so I have to do the prep work outside as well.  I like to hit the parts with a light blasting to give the paint something to really stick to.  Just an extra step that I feel results in a better end product.

Once we start getting a few nice day's I'll be right back on it.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on September 26, 2017, 09:40:19 PM
Update, I had some issue the prevented me from Cerekoting the parts so I bought another lower that was already painted and milled it again.   ;D

Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on September 26, 2017, 09:41:16 PM
More pics...
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on September 26, 2017, 09:42:31 PM
And some more...


Hope to get the rest of the gun assembled this week, the season is closing in fast.


Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on September 27, 2017, 08:38:07 AM
Woo Hooo, A friend has offered to Cerekote the remaining upper parts for me with some coating that he had left over from one of his projects if I cover shipping.


Looks like this may actually come together the way I intended after all.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on September 27, 2017, 08:54:57 PM
Thanks for the update on your project - for some reason I got to thinking about this when I was down in the gun room last weekend.  Based on the lessons you learned on the first lower, did the machining of the second one go better for you?  Also curious how your jigs held up through the two lowers - could you use that on quite a few more or is it already starting to show some wear?
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on September 28, 2017, 05:44:48 PM
Mad, I learn a little more with each one.  This time I used my guages to measure the distence from the top of the table to the top  of the lower.his gave me a point of reference when measuring the depth of the trigger pocket.  This one I nailed at 1.251"  The jig comes with a measure to adjust depth but I prefer to use the guage as well to be more accurate.

I also made sure the bit was tight int the router after every other pass when I stopped to vacuum out the pocket.   I milled a plastic upper where the bit came loose and ripped through the bottom, screwing up the trigger hole.

I have completed three with this jig so far, two alum and one polymer.  The polymer was more of a test run but it worked good except for the above mentioned issue with a loose end mill bit.

When drilling the pilot holes I did not use enough cutting oil the first time and dulled several drill bits.  This time I used copious amounts and each one cut like butter using the same bit.

I am noticing some wear around the top of the templates where the end mill bit rides when cutting the edges.  This is resulting in a slight wave pattern if you run your finger across it.    I may be putting too much pressure on it with the bit when cutting the edges.  I will check when I assemble the lower whether that resulted in too much play around the trigger and hammer.

Overall I am impressed with the quality and ease of use of this jig.    I see they have an updated model out now that allows you to mill a 5.56 or a .308 lower using the same jig in different configurations.  ;D

I do want to eventually build a .308 from a 80% lower.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on September 28, 2017, 08:15:45 PM
Sounds good - thanks for the feedback.  I've toyed with the idea of building one up from an 80% lower - not sure if I'll get myself talked into that or not.  Haven't messed around with the polymer lowers yet either - almost bought one a couple of years ago (a finished lower) when parts were hard to come by, but found a guy locally who had a stripped S&W on the shelf so went that way instead.  Really curious how the polymer units handle the extremes of hot & cold temps.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on October 13, 2017, 06:26:45 AM
Making a little more progress when I can make the time.

Finished assembling the upper (sans scope).   The dust door should be arriving today or tomorrow, I decided to go with something different than I had originally planned.

My friend did a great job on the paint.   He painted the scope and rings so they match as well.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on October 13, 2017, 04:26:35 PM
Looking good!   Good luck with the dust cover - that itty bitty little C clip on the end of the pivot shaft has a tendency to make me crazy.  On my last build I either had a fat C clip or the slot in the rod was too tight - I think I exercised my full four letter word vocabulary before I finally got it to stay put.  It can be really tough to find that little clip when it drops to the floor - did it twice!
 --099-780
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on October 13, 2017, 07:32:40 PM
Trying something different this time, found a quick release dust cover.

More progress tonight. Got the scope mounts installed, lapped, scope mounted, aligned and everything torqed and lock-tite'd.

Also finished as much of the lower as I could. Still waiting on the fde grip.

Once the rest of the parts arrive (eta tomorrow)​​ all I need to do is add a bit of the camo to break up the outline and shoot it.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on October 14, 2017, 10:52:26 AM
Looking good MI-B - when I saw your pictures a couple of days ago I thought it was olive drab, but in the one with your lapping tool it's much more clear as FDE.  I like it, anxious to hear your thoughts after you get a chance to shoot it.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on October 14, 2017, 02:08:42 PM
That is looking real nice, Mike. 
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on October 14, 2017, 05:50:23 PM
Done! May add some camo but pretty much done.

Funny how no two pieces of FDE are exactly the same. LOL


The flourescent lights in my basement make it look green.
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on October 14, 2017, 05:51:07 PM
More
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on October 14, 2017, 05:51:36 PM
Last
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on October 21, 2017, 05:09:36 PM
I really like this little thumper!!!!

I made it out to Williams Gun Sight for an hour this morning to shoot it for the first time. All shots were at 100 yards with factory 250gr Hornady black box ammo.

Right bull on right target is my first string of three after boresighting.

Left bull on right  target is next three after adjusting scope. My best group of the day.

Not bad for the first 6 shots. The Geissele two stage trigger rocks, scary crisp.

Left target are more shots after adjusting the scope to be about 2" high at 100.

Center, lower circle of right target was last 6 shots.

Had a few loading issues, if you slap the mag in too hard with an open bolt the round tips up and will jam on loading.  Will have to play around and see if its a mag issue or just inherent to this round.

This kicks about as bad as a 20g with field loads. I can feel it after shooting a whole box. Due to some shoulder issues I really can't take to much any more
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on October 21, 2017, 05:26:46 PM
it looks like a good shooter. nice work MI
Title: Re: Building an AR-15 in 450 Bushmaster
Post by: [Blocked] on October 21, 2017, 07:10:00 PM
Excellent, always good to shoot one after many hours of getting it together and having good results.  Looks like it will be quite functional.