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Author Topic: Loading Beyond Max Loads  (Read 376 times)

Offline Dutch-Hunter

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Loading Beyond Max Loads
« on: December 13, 2017, 05:33:02 PM »
Remember Madgomer asked for this.... ;D

First I never recommend loading above max to anyone. However I seldom load much below the max. My LongDoc (338/378 WBY) Custom build has a 2.25" OD barrel. The action was patterned from a 50BMG and is also over sized. My starting loads were above max load and netted me an average velocity of 3260. I pressed on and found the most consistent velocity of 3940. The 3260 was 10% over recommended max. Consequently the 3940 is 35% over. Computing the free recoil value for this screamer equals 96 pounds. Even with LongDoc's heafty weight of 32.75 pounds there is still a significant felt thump.

Now, the answer of your question Mad... Sit on down and get ready for a lengthy read.

A maximum load is a "predicted" maximum powder charge, and while it can be an overload, itís not quite as dangerous as many reloaders imagine it to be. In recent years the people who compile reloading manuals have erred on the side of caution and reduced their maximum loads. This was done for a perfectly good reason. Too many handloaders looked at the data, were impressed by the velocity of the maximum load and set out to work up from there. Of course, they found trouble with excessive pressure right from the start. This was incentive enough to have maximum loads reduced slightly. If you were to check an old manual you are likely to find a reduction of at least 2 grains between the old and current maximum charges.

This doesnít mean, however, that itís safe to start with a maximum load when you commence working up data. And you definitely should not! Maximum powder charges are listed as the likely level where you can expect your loads to top out. They are intended to give an indication of when to stop adding powder. Despite being slightly reduced, all maximum charges should be treated with respect and once you reach that point, you should proceed with the utmost caution, even if the fired cases and rifle donít show any signs of excessive pressure.

Maximum loads are not carved in stone. They canít be because of all the variables. Just how much powder can be used in a certain caliber with a particular bullet weight depends on a great many factors; the type of action, the make of case, the type of rifling, the rifling twist, the bore and groove diameter, the throat length of the chamber, the primer, the hardness of the bullet, the amount of bearing surface it has, and so on.

Some makes of cases are heavier, due to having thicker brass and hold less powder than others, they will show pressure signs quicker. At least one make of magnum primer designed especially for heavy charges of slow-to-ignite powder, increases pressure if used with smaller amounts of easily ignited powder.

Bullets with hard jackets and cores and longer bearing surface can increase pressure. Bullets that are seated out so that they are jammed into the lands at the lead raise pressures enough to expand primer pockets and cause gas leaks. Bullets seated so deep that loading density is increased can raise pressure but not as much as those jammed into the rifling.

Chambers with long throats cut so the bullet has to make a considerable jump before it engraves the rifling result in lower pressures.

Always bear in mind that cartridge cases that are thicker, have less capacity, and will give the same pressure and velocity with less powder than another make of case which has more powder capacity and thinner brass.

Some actions are capable of handling more pressure than others. The brass case is the weak link, and actions that support the case with the steel of the chamber or the recessed bolt face clear up to the extractor groove will handle more pressure than actions that do not.

Actions that enclose the case with steel to the extractor groove are the Model 98 Mauser, the Ruger M77 MK II, Weatherby Mark V, the post 64-Model 70, the Dakota 76, and the Model 110 Savage. The Model 1903 Springfield, the Classic Model 70 and the 1917 Enfield all use a coned breech that leaves a little of the case sticking out. But with good modern brass, all of these actions are safe and can withstand higher pressures.

In this modern day and age, all the ammunition companies together with makers of bullets and cases and propellant powders have equipment for taking pressures and velocities. Most of them put out manuals containing data for handloaders. These manuals usually give such valuable details as the make of case, the make of primer, the make of the bullet, the length of the barrel, the pitch of the rifling, and the maximum cartridge overall length. They also list the maximum case length and the trim length.

Another thing for the handloader to remember, is that if the load he settles on gives easy extraction and he can reload his cases from 10 to 30 times without primer pockets becoming enlarged, that load is safe in his rifle with the components he used.

On the other hand, if his cases are hard to extract and after three or four loadings he finds that primers slip into the primer pockets with little or no pressure, the load he is using is too hot no matter what the maximum is supposed to be. If he gets primer leaks or a blown primer, he has definitely exceeded the maximum charge for his rifle.

Load development might be defined as the detailed execution of the planning of a handload for a specific purpose. This includes a fair amount of experimenting and testing to ensure that the load is safe. You should begin with a powder charge below the listed maximum and work step by step upwards until the desired specification for the projected load is achieved, or until it becomes obvious that it cannot be achieved safely with the selected components. This is where I now use the Incremental Load Development Method.

If the handloader has a micrometer, he should measure the solid head of his cartridges before and after firing and compare the measurements. On rimless cases, the reading is taken on the case head immediately forward of the extraction groove, and on belted cases the head forward of and adjacent to the belt. These are the best locations to read and record this dimension.

All cases expand noticeably in these areas on first firing, whether with factory loads or handloads, so this technique cannot be used on this firing. That first firing will expand the case to match the dimensions of the chamber in which it has been fired and any further expansion on subsequent shots is a sure indication of very high chamber pressures.

Case head expansion after firing is the handloaderís key to acceptable pressures in his reloads. If the micrometer shows the cartridge case head has expanded by as much as .001Ē then that pressure is excessive for that shot in that gun. Some experts claim that even .0005Ē is too much, but by my rule of thumb this is the outside limit of permissible expansion. I always try to keep my working loads under .0001Ē expansion, and recommend this as a sensible limit for the average handloader. What it all boils down to is: if the dimension shows measurable head expansion, then brass is beginning to flow because the pressure is too high. This is a sure indication that it is time to reduce the powder charge.

If, as we shoot a series of pressure loads, and check each increased powder charge with the micrometer, no pressure signs appear, the next heaviest charges are fired, and so on through the series. On a rare occasion, it may be that no sign of excessive pressure shows up even when you reach the listed maximum load. You may even be able to exceed the maximum charge weight recommendation in your manual with safety. But this only means that your particular rifle has a chamber dimensionally larger than standard, which makes it more tolerant of those maximum charges than the test gun used to compile the handbook data. Most loads are tested in a barrel with minimum dimensions which is attached to a universal receiver, but some ammunition makers, like Norma for instance, take pressures using factory rifles.
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Offline Madgomer

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Re: Loading Beyond Max Loads
« Reply #1 on: December 13, 2017, 06:52:17 PM »
Good stuff DH, as always, I certainly appreciate it.  And as always with me, when I get one answer I generate more questions. 

In the case of variability in case volume from one brass manufacturer to another, does that stay pretty consistent over time, or will that vary considerably from lot to lot?  For example, if I have some Winchester .223 Rem brass, and I use that as my baseline, and I figure out that .2 gr less powder in a Rem case yields the same velocity and .3 gr more powder in a Hornady case hits the same point (same powder/pill/primer and dimensions) can I count on the next bag of brass from that source having the same relationship to the baseline or is it just a given that I re-baseline that new brass?  I assume the latter, but would love to hear your opinion.  If they're consistent over time, has anyone ever published a comparison of charge weights for brands A-Z which equate to a common muzzle velocity?

On your case head expansion topic, are you making those expansion comparisons after only neck sizing the fired case, or full length sizing & comparing sized vs fired diameters?

Thanks again for sharing the knowledge, this is very helpful!
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Offline Dutch-Hunter

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Re: Loading Beyond Max Loads
« Reply #2 on: December 13, 2017, 08:15:45 PM »
First question about brass thickness change as you fire the case. Brass will all flow (stretch) as it is used. Thinner brass will not consequently have as longer lifespan as thicker. Mostly because of the metallurgy of the brass. When cases are formed they are extruded. The pliability of the alloy determines how thick the walls will turn out. The brass as I said flows towards the muzzle, this is why you must continuously check the trim length. Every now and again you must bump the shoulder back.

Which brings us to your second question. I fireform all of my new brass. Then neck size only until the shoulders need to be bumped back by full length sizing. I once full length sized I fireform again. Which then brings up another operation; annealing. Annealing brings the spring back to work hardened brass.

My Bro Bo and I always weight EVERYTHING! Sort into groups of a +/- parameter. So yes you should always determine your baseline.

I have never seen a charge weight comparison for different brass makers.
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Offline BoBallistic

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Re: Loading Beyond Max Loads
« Reply #3 on: December 14, 2017, 08:26:53 AM »
Dutch - Thanks for another great thinking man's article....if you reload you got to copy this and save it....was resizing last night.....

Yes, I do weigh everything, including myself...LOL...including primers, bullets and a file that tells me the neck thickness of each round after each shot...I know that I am crazy to do this....but have the tools and now the time to do this the right way.....

When I get new preferred Lapua, Norma, Nosler brass (and other manufacturers), run them through the size die and check the length and trim them up if necessary! Then I load the round and then head to the range....after firing all 50 rounds and am getting ready to resize them and then check the length and will have to trim every round some....and will check the neck thickness before trimming the brass....they will write it down the thickness and then start trimming......

After the second and third and even the forth firing, the brass has seem to be stretch out to the max but then you have to start worrying about the necks and base getting to thin. My ideal goal is to reload each piece of non-mag brass seven times but some brass just won't let you go seven times....Magnum rounds I normally try to get 5 loads out of it, but normally is only three times! But looking at each piece of brass under the round lighted magnifying glass and if a crack is spotted that brass goes into the recycle bend!!!

The big question is how thin is too thin to seat a bullet and make sure it will stay where you have put it in the case!! Back in the early days, I have several pills/bullets that have been seated at one depth and when I reached in to get them to load up the rifle you can tell that the seating depth has changed, some how the bullets have seated deeper into the casing!!! But too thin your pills will not seat probably and the neck tension will be erratic around the bullet.....so you have to measure the necks when you reload....and do each piece!!! especially on the third and forth loading....

The method I use is to put a label on each the plastic 50 round ammo box on the outside of the box with the numbers 1 thru 7 on it. I will cross through the number after each time the brass has been measured and sized...may have only 45 of the 50 left in there due to cracks and dings or just lost brass.....

Going back to the beginning and saying that I weigh everything...here is a story and it results target attached that I would like to share.....When I got my second Cooper Rifle Varmint 308, 24" barrel, Swaro AV 3-10X scope, it was a used 308 and had 400 rounds already down the barrel of it (the original owner told me it had about that number of rounds down it)...so after tearing the rifle completely apart and checking to make sure it was what they said it was, I got my Hawkeye Borescope out and clean the barrel and looked down the barrel, clean some more...etc....next I loaded up 10 rounds, taking 10 rounds of weigh the same or close within a grain or two of each round....had Lapua, CCI primers, 168 gn Berger VLD..... 45.14 grains of Varget powder....the astounding thing about it that after assembling the round between all ten of them there were only less than .75 grains difference in the 10 rounds......head to the range and shot the first three into the bank for fouling shots.....then I did a group a 100 yard see target 005 attached (shots 4,5,6).....took the rifle home and did move the cross hairs down to about an inch high at 100 yards.......so the following week went back to the range and fired shots (7,8,9) as shown on target 006.....The 10th and final round went through a deer neck see attached pictured.....



 
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Offline sundowner

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Re: Loading Beyond Max Loads
« Reply #4 on: December 14, 2017, 03:52:05 PM »
Thanks for the info Dutch , always good to learn more about reloading .  ##$%#115 ##$%#1118
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Offline BLUETOE

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Re: Loading Beyond Max Loads
« Reply #5 on: December 15, 2017, 07:36:10 AM »
Thanks Dutch and Bo great reading.
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