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Author Topic: Developing a Load your Gun likes...  (Read 1599 times)

Offline Dutch-Hunter

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Developing a Load your Gun likes...
« on: April 16, 2013, 06:36:01 PM »
Methods to Develop a Load that WILL work in your rifle.

IMPORTANT PLEASE READ
Before I continue; Excessive Pressure Warning Signs (A few words of warning)
I thought we had better discuss the warning signs of too much chamber pressure. As the case pressure rises something has got to give and once the bullet cannot give fast enough this pressure can get very dangerous, for your rifle and you both. The first and easiest sign is how the bolt works after firing a round. I only use my index finger to unlock (lift, not to be confused with pull) the bolt after I take a shot. I know every bolt has its own “feel” you must learn that feeling. If you unlock the bolt with your finger and thumb you lose some of the resistance perception. Bolt opening resistance greater than normal is your first sign of chamber pressure issues. In the old days, you continued the load process until groups tightened up significantly or until you had to pound the bolt open with a mallet (over exaggeration but possible). The second way to watch for excessive pressure is to examine the primer of every spent shell. Make sure it is seated as deeply and squarely as when you installed it. Primer deviation (blowout) can occur before bolt resistance, but not always. Then you must also be consistent in primer seating. The third way is a little more detail oriented. Nowadays, the ballistic fanatics and velocity junkies among us (OK me) stop when the case head shows 0.0003" expansion. This is measured by a good micrometre with a vernier scale (there digital ones available now but spendy), which enables you to measure to a ten thousandth Inch. There are other signs too but if you at least watch the first two you will be fine. I should also mention pressure will increase with a dirty or neglected bore, just saying. “If it ain’t clean, it could be mean!” Granddad said.

Load development the Old Fashioned Method
For many years the classic method to develop loads was to start with a particular Bullet, Powder, and Primer. Then load five rounds with a supposedly safe start load and to shoot a group. If the pressure signs (bolt lift effort , primer appearance, case head diameter, etc.) seem to be normal, or at least not excessive, try another five round group with 0.5 grains more powder, of course, the same powder.  If the results were not satisfactory then try another .5 grains and so on until hopefully the magic number reveals itself or pressure gremlins invade. I assume everybody knows if 40.0 grains of 4895 are OK, you should not try 40.0 grains of BulIseye, you may not live to tell about it. Always check your load manuals for safe minimum and maximum charge weights for the bullet and powder being used.

If you did not get the accuracy you wanted or expected, you tried another Powder, or Primer, or Bullet and start all over. Sometimes this process would have worked very fast. Sometimes it would not. This process can actually take years. Then when you finally come up with THE load, your barrel may only have a few hundred shots left in it. When this procedure did not produce the accuracy you hoped for, you wound up burning up a large quantity of components and putting more rounds than you wanted to through your barrel, before you either found a load that worked to your satisfaction, or you decided, the rifle or barrel is a stinker. Then you start it all over again.
 
The round number you might have to fire, before you find a good load can be a significant percentage of your accurate barrel life, particularly when you try to develop a load for a magnum. There may be a better way. Although I must admit I have not tried the following method it sounds good.

Incremental Load Development Method (ILDM) (Since I first wrote this I have become a firm believer in this method. It saves a considerable amount of components and time. It also gets you to THE load your rifle likes quicker. If you change a component or components then you’ll have go through the process again. I have posted the ILDM target I use in the firearm section. If you can’t find it or would like a copy send me a PM with your email address and I’ll get it to you.)

This load development technique can tell you quite a lot about a rifle and the components it likes and at that velocity levels it will shoot best. I first read about this method in an article by the late Creighton Audette titled, "It Ain't Necessarily So".
 
Creighton Audette’s Incremental Load Development Method (ILDM) in essence is: “Settle on Choice of Bullet, Primer and Powder and Case brand. Once you picked these things, there are two numbers you have to make up to use this method.” Start load and a Load increment. That chosen, load 20 Rounds, start with the Start load and increase the Charge weight stepwise by the Increment for each subsequent Round. Load only one Round with each Charge weight. Then, using the same Aim point, fire all these Rounds on one Target and interpret the results. Here are the details. Depending on each Bullet weight, base the Start load on both Increment and Maximum load for the Powder you picked, so we shall look first at increments first. Some examples are in order.
 
For medium case capacity cartridges such as the .308 Win. or .30-06 Sprg. Audette's standard increment was 0.3 grains. For small cases such as the .222 Rem, .223 Rem and the like, use 0.2 grains. For medium-large cases such as the .30-338, 0.3 shall also do.
 
Your starting load (charge weight) should be simply the recommended maximum charge weight for that cartridge with that bullet minus a decrement, which is 20 times the increment. Example: If your maximum safe load is 46 grains and the increment is 0.3, the decrement would be 6.0 (= 20 times 0.3). In this example the decrement would be 6 grains. Your start load must be safe with the used components. WARNING: If you fill a really slow powder, such as 4350 or slower, do not fall short of the recommended minimum safe load for that powder, to avoid the risk for secondary explosion. The Secondary Explosion Effect occasionally occurs with light loads of slow powders, or partly empty cases with some slow powder. It happens not every time, but is frequent enough and dangerous enough, that almost all load manuals now list minimum charge weights for slow powders. If you fill such a powder, look for warnings and heed them strictly.
 
The next step is to load up a set test rounds by loading only one round, that's right, only one round, with each charge weight. Start with the Start load and load six rounds with it. Then load the next round with 'Starting charge weight + the increment' then the next round with that load plus the increment and so on, only one round at each charge after the beginning loads. Until you reach the maximum safe load. An example will make this clearer.
Example: If the start load is determined to be 40.0 grains of IMR4350 and your increment is 0.3 grain, then load the 1st Round with 40.0 grs., the 2nd with 40.3, the 3rd with 40.6, the 4th 40.9, the 5th 41.2, the 6th 41.5, and so on ... . Twenty incremental loads will take you the ladder up from 40.0 to 45.7 grains in 0.3 grain steps. While loading keep the cases organized in a load block, to always know from its location in the block the charge weight in each case. And, yes, approximate weights are not good enough; weigh each charge to a tenth grain (1/10 gr.) exactly.

Once 20 rounds are loaded in this manner, arrange them all in an ammo box in increasing charge weight order and you know precisely each particular load. After step 1 below progress through the test loads starting with the lightest charge and shoot them in charge weight order. To learn the most Information from your efforts, you should do some things at the range:
1.   Start with a clean barrel and shoot about 5 foulers rounds, loaded with the start load before you begin the ladder test. The benefits shooting the foulers are;
a)   allow you to get on target and insures your group on the target to a wanted aim point.
b)   enables you to properly position and adjusted your Chronograph screens,
c)   foul the barrel properly with powder foul from the powder used for the incremental ladder test (this is important).
After a load with one powder changed to another powder, even though both powders were from the same manufacturer, a barrel may need as many as 4 or 5 Rounds to "settle down". Start with a clean bore and then to foul it with a group shot with the start load results in a controlled beginning.
2.   Starting with the lightest charge shoot the ladder test rounds in increasing weight order.  As you approach the maximum load level watch for excessive pressure signs. If they appear, stop!
3.   If possible chronograph all Shots. Velocities should steadily increase, but an occasional oddball shot may yield an off-order-velocity. By logging the shot velocities helps to interpret the target.
4.   This Step is the KEY to the method: Shoot in a single series all rounds on the same target using the same aim point. Number the shots and shot holes to identify best which shot caused which hole in the target. Take good notes. Always be sure to write down any pertinent data, such as the fact that you saw the crosshairs sights fade to the right, or down, or wherever for any particular shot. This information is needed to interpret the data.
5.   Shoot the test at a good distance, at least 200 yards, but 300 yards is better. Creighton advised in his article to use 300 Yards. The problem with shooting the series at 300 yards is that it is very difficult to identify the shots by number on a target that is that far away, unless you have a superior Spotting Scope, and it is a very calm day with no mirage. The ladder test can work at only 100 Yards, but sometimes, to discern what happens on the target, can be difficult. At any distance on a range, you will have to resort to plot the shots by number on a target diagram. It is advantageous to have someone else to watch the target through a Spotting Scope and do the diagramming.
6.   Another important rule to obey to successfully learn from a ladder test is to set up the rifle exactly the same way you intend to use it later on. This means, if you intend to use the riffle with a scope, and then shoot the test with that scope on that rifle. This ladder test should be shot from a rest, or other support, to assure the aim site is exactly the same with every shot.”

If you shoot a ladder test with a rifle set configuration other than its intended use, the rifle's recoil and vibration characteristics differ enough, that the load you find, may not be optimum. Shoot any ladder test with the rifle set up the way you are going to use it! Exactly!

After you finished the shots sequence, you have two data collections, that, when looked at together, can tell you a lot about your rifle. They are:
1.   The data sheet listing the loads and their velocities and the target with the numbered shot holes, or the target together with a target diagram with shots numbered, self.
2.   The target with the numbered shot holes. This is the more important of the two.
To plot shots on a target diagram, to have the target itself to compare to the diagram is still useful. Usually this helps to correct the diagram and enables to number most holes in the target.

Interpreting the Data
As velocity increases the shot holes should pattern up the paper. The lowest velocity shot will usually hit the target lowest. The highest velocities shot will usually highest hit the paper. In this upward ladder there may be clumps. Those are of all most important. Sometimes hits clump nice little round spheres. Other times hits clump only vertical. If in windless environment the hit holes scatter from right to left, as well as up and down, probably time to try another powder or another primer or to check the action bed in the rifle has arrived.
However, with any Powder and Primer combination this usually happens, within the 20 bullet impact pattern on a target, five or six consecutive shots clump someway, can be found. This does not happen  randomly. The numbered shot holes will march up the paper, then stop for a few shots and clump, before jumping out of the clump and then resume their upward march.

The KEY to interpret the pattern, are all numbered shot holes. You could shoot with all sorts mixed Loads with different Bullet weights, different Powders and Primers, different Cartridge cases brands, etc., 20 Shots at one Target and probably get a few nice three or four shot groups and maybe even a small five or more shots group somewhere in the 20 hole pattern in the target, but that wouldn't mean anything. Even all matched components everything else correctly arranged with the ladder test, would a small group not mean anything, unless that group was made by consecutive shots in increasing weight charge order.

We only look for small groups formed by consecutive shots. Let’s call such groups "Sweet Spots", there the fired Rifle "cares not” about the powder charge weight, as long as it remains in a certain range. The heart and soul of the ladder test is simply to find a charge in the middle of the “Sweet Spot” group charge weight range. One benefit to find a load with this method is, a load, tolerant to minor powder charge weight variations. Even if your powder measure technique is not so accurate, the Incremental Load Development Method (ILDM) with the ladder test will show which load is most accurate with known charge.

The Ladder test works because...
If you look at the reason the right way, it is simple. As the powder charge increases, the muzzle velocity also increases, but the time the bullet accelerates in the barrel (barrel time) decreases. As powder charge and muzzle velocity increases, recoil also increases, whipping the barrel. The recoil induced muzzle elevation interacts with barrel vibration and barrel time effects, work in the ILDM.
Several forces work in the same time:
1.   The recoil forces the barrel to move back and to rotate slightly around the Rifles Center Mass (whipping the barrel).
2.   Responding to increased powder charges the further accelerated bullet increases velocity and reduces barrel time.
3.   The barrel vibrates in some regular manner, changing the direction to point to.
The first two Forces combine to produce a recoil effect. Force 2 combined with #3 also produces a vibration effect. Recoil effect and the vibration effect combine to the total effect, to be seen as the target pattern. We need to look at these effects individually. ILDM allows us a window into the results of these forces. This insight can serve as a benchmark on which to base a particular load for a specific rifle to be used in a specific manner.
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Offline yari

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Re: Developing a Load your Gun likes...
« Reply #1 on: April 16, 2013, 07:42:27 PM »
wow!!! all i can say is i'm glad i'm a bowhunter. that's a lot of info.

thx dutch
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Offline MichiganLouie

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Re: Developing a Load your Gun likes...
« Reply #2 on: April 16, 2013, 08:59:46 PM »
I remember when I first started loading metallic cartridges.  I picked an oldtimer handloader's brain for best  powder, etc.  I picked a bullet weight, and loaded 4 groups of 5 rounds each.  On each group the  powder charge varied by. 5 gr.  As I shot each  set,  I could feel the recoil increasing, and surprisingly enough, the faster the bullet went,  the tighter the group.  The last group measured 1-3/8",and that was good enough for punching paper.  I live in a shotgun only zone and rarely hunt outside it.   I may print out DH's post for future reference.
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Offline Dutch-Hunter

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Re: Developing a Load your Gun likes...
« Reply #3 on: April 16, 2013, 09:37:33 PM »
Louie... If you ever get a chance to load up rifle rounds again, try this. I loaded for many decades the same way you did. I then had my AHA moment. The proverbial question was; "Why didn't I do this earlier". The incremental load method is incredible. The only drawback is the yardage needed to get easier to read results. I first ran one at 200 and it was hard to measure the clusters, once I stretched it to 300 it got easier to see the velocity groupings. Then I fine tuned the selected load at 400 to get a real handle on the exact load to use. I can't wait for a little better weather to run it with the Catbird. The loads I got with the gun performed very well but I like to load my own. That way there is only one hind end to kick when it misses.
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Offline MichiganLouie

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Re: Developing a Load your Gun likes...
« Reply #4 on: April 17, 2013, 07:25:29 AM »
Dutch, I never stopped reloading rifle ammo, I only stopped trying to develop loads.  I initially started out with 748, 4064 and 3031, so I just took published data, used their recipes, and if it grouped ok. I was happy.   I have room to shoot 100 yds behind my house, maybe a little further, definitely not 200 yds.  Without a spotting scope, it's difficult to "read" your target beyond 100 yds.  at least for me.  Nowadays, I find myself reloading mostly pistol ammo.
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Offline Jaeger

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Re: Developing a Load your Gun likes...
« Reply #5 on: August 16, 2015, 01:23:29 PM »
This is an old but very interesting article, especially valuable when using expensive bullets.

Question, what was the time increment between shots?  After the 5 foulers, does the method contemplate letting the barrel cool partially or completely?  20 shots seems a lot and will heat up the barrel.
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Offline Dutch-Hunter

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Re: Developing a Load your Gun likes...
« Reply #6 on: August 16, 2015, 06:31:48 PM »
Cooling time varies on the barrel contour. Best to take a temp reading at various spot along the barrel. After each shot take another set of readings. Let the barrel cool to at least 5 degrees to ambient. This will allow you to determine the "cold" temp reaction of your barrel. Most hunting shots are taken with a "cold" barrel.

In addition by taking temp readings you can see if your barrel has any "hot" shots. Before starting to work up accurate ammo make sure you gun is ready. Make sure the barrel is floated and best case lap the bore or have it lapped. Barrel restriction will cause hot spots.

I'll be glad to answer any other questions you may have. Sorry this answer was so brief I'm not home and occupied on another commitment.
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Offline Foss1lHunter

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Re: Developing a Load your Gun likes...
« Reply #7 on: December 10, 2015, 12:03:13 PM »
Thanks Dutch!!!  This is great information for me as I am new to reloading.                               
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