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Old August 8, 2012, 03:28 PM   #26
kraigwy
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Everyone serious about shooting and developing loads should read "The Secrets of the Huston Warehouse"

In addition, read this:

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA542434

The above link is about testing military ammo, besides case prep it was discovered that getting the bullet seated staight in the case is critical.

The link confirms the findings in the Secrets of the Hustion Warehouse.
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Old August 8, 2012, 07:09 PM   #27
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To me the correct answer to all three is, it depends.

First, it's a math problem. Sources of error that affect group size don't add up linearly. They add up the way standard deviations do, as the square root of the some of the squares. Each source of error adds a certain amount of area to the group, and the bigger the group gets, the smaller the change in radius is needed to eliminate that same area, so the less significant it is to the diameter of the group.

YAWWWWWN! (There he goes again. Why should I care about the math?) Well, in this case its because it tells you why some accuracy loading steps matter to some guns and shooters and don't seem to help others at all.

Suppose I turn case necks on a benchrest gun and it improves my 100 yard groups from 1/4 in circles to 1/8 in circles. A 50% improvement! That's the difference between winning and not even placing in some benchrest matches. A very big deal! So, now I load the same ammo into a hunting rifle that normally shoots 2 in groups without neck turning. How much will neck turning improve the groups, assuming it has the same amount of effect? 1/8 in? Nope. Changing a 1/4 in group to 1/8 in removes 0.037 in² of area from a group that started with 0.049 in² of area. A big percentage. But if I subtract 0.037 in² from a round 2 in group (3.14 in² of area), The same change is a much smaller percentage. It will only improve a 2 in group by about 12 thousandths of an inch. Pretty impossible to see, given that it's less than the random group size variation from one group to the next.

So the trick is to address the dominant issues in your gun. What they are will vary with the platform. Are you going to worry about getting bullets perfectly straight into the cartridge, reducing it's runout? Well, Harold Vaughn showed 0.004" of bullet tilt only affected group radius by about 0.36 moa in a tight benchrest platform. But A. A. Abbatiello showed that in a much looser miiltary type match rifle chamber that same 0.004" of tilt made almost 2.0 moa of difference on target. So does it matter to your near 2 moa hunting rifle? It might be the main accuracy issue you have. Or with your bullet and chamber it might be another almost invisible factor. There's only one way to find out.

Components are different, too. Hatcher described loading two stick powders for National Match ammunition one year, both about like modern IMR4320, but one with a short grain and one with a long grain. The Frankford Arsenal loading equipment could dispense the short grain to ±0.3 grain precision (0.6 grain span). It could only dispense the long grain to ±0.85 grain precision (1.7 grain span). Yet, the coarse grain ammunition shot consistently better groups than the short grain loads and was selected for that year's national match load and several records were broken with it. Powder combustion is complicated and is affected by space between grains. My guess is that powder in the particular charge weight chosen behaved such that when the grains were more tightly packed it slowed the flame front passage just enough to make the powder behave as a slower burning powder would. The result was that increases in charge weight were compensated for by decreases in burn rate, resulting in bullet barrel time remaining about the same.

But who knows. A. A. Abbatiello used NM ammunition sorted with a runout gauge. If he'd been able to change the seating depth, would the runout still have been as critical? I don't know.

Twice in my life I've encountered guns with barrels so badly made that the rifling was unevenly deep on opposite sides of the bore. Both of them tumbled and keyholed anything you shot through them from about 25 feet on. One was a S&W m. 41 .22 Rimfire target pistol. The other was a 4" barrel on a Dan Wesson v.15. I've not seen it in a rifle, but see no reason it couldn't happen there, too. It's one instance in which the barrel has to go or no loading practice you have in mind will make any difference to it.

I've also watched fellows so nervous they couldn't stay on paper from prone position at a local 100 yard reduced range match. It didn't matter for them how good or bad the guns or the ammo were. On the other hand I've been pleasantly surprised by how many beginning match shooters will arrive on the line with something looser than Fibber McGee's closet, declaring it shoots better than they do, only to find their best scores improve 10 or 15 points if you persuade them to borrow an accurized loaner rifle.

So, the bottom line is that shooting is a shooter, gun, ammo system. You have to decide where the weakest link is. If you can eliminate the shooter by shooting from a bench, that's one variable down, though most I see can't eliminate him as completely as they might believe by that course of action. Still, you have to figure out what matters to your gun, then address those factors in your loading and not others.

I'll mention one last thing. One year I tried shooting 2520 in my M1A. That gun normally shot about 0.7 moa from prone, but with 2520 it was more like 1.2 moa. I tried adjusting the load, the seating depth and other physical factors. At the time I was using Federal 210M primers, being blissfully unaware of slamfire talk and also didn't know going to a magnum primer could help spherical propellant ignition. What I tried was deburring the case flash holes. Bingo. Groups dropped to the usual 0.7 moa. That deburring never made a hint of an improvement with any stick powder I had in that gun. But with that primer and that powder at the charge weight I had under the bullet I was using in that rifle, it mattered.

So, which loading steps are most important? It depends on where in the particular system the dominant error is located. You can see how, in the last example, if I'd never tried anything but my favorite stick powders, I might have concluded that deburring flash holes makes no difference at all. It's easy to fool yourself into concluding things that are true for your particular shooting system(s) applies to all others as well, but that doesn't make it so. The only thing I know to do is try things until you find out what matters to the weapon(s) in question. Also, based on the math, things that didn't matter when your groups were big can begin to matter as your groups get small.

So like I said; it depends.
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Old August 8, 2012, 08:54 PM   #28
ATPBULLETS
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Awesome answers .... thanks very much...
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Old August 8, 2012, 09:13 PM   #29
ROGER4314
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Geeze, a reloading thread that hits the nail on the head and tells it straight! Well done!

Since the OP was looking for things that he could do to improve accuracy, I'll toss this in............

Anything that you do to improve consistency will help but throwing a ton of money at the issue won't guarantee a major return in accuracy. I'd like to address getting the best accuracy for the money spent.

I've experimented with almost every aspect of reloading to get the magic reload. I've weighed and sorted cases and bullets, weighed every powder charge, fiddled with primers on & on.

I read the post about powder charges being fairly unimportant as long as they're in the ballpark and it made me smile as that's exactly what I found.

I found that the biggest single factor in component selection is internal case capacity. The cases are formed differently and outwardly look the same. Internally, however, the volume of the cases varies a lot. Once, I sorted by case lot. Now, I just sort by brand. It matters. edit...This is not a big factor in pistol rounds. It is a major factor in long range rifle rounds.

I'll continue............
Loading match bullets at SD pistol distances is a waste of time and money. The return just isn't there. That is based on Ransom Rest tests and chronograph readings. Revolvers invariably have one chamber that isn't exactly like the others and there's not a lot you can do for that.

Match rifle bullets really come into play after 200 yards. At 200 or less, it doesn't make a lot of difference as long as you use a quality bullet.

At 600 yards, it's all about bullets and keeping them supersonic.

This is based on NRA position match shooting from 200-600 yards. I am NOT a benchrest bug hole shooter! Their opinion is probably different.

Flash

Last edited by ROGER4314; August 9, 2012 at 11:45 AM.
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Old August 8, 2012, 11:09 PM   #30
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I still have few tight neck rifles and lot of good rifle being build with what's called no-turn-necks.

I think most reloaders as they gain experience they have certain things they consider important vs having a list of do's and don'ts.
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Old August 8, 2012, 11:54 PM   #31
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Sort Headstamps?

I have shot over 300 groups each in 9x19, .40S&W, and .45Auto. In each case, they were matched between cases that had the SAME headstamp and as close to the same weight a possible compared to a grab bag of random never-heard-of headstamps.
Averaging through all this data, for each caliber, the mixed brass tended to have an average smaller group size by about 0.20-0.45" in all three cartridges.
Comparing those cases where the matched cases produced a smaller group and where the mixed (and I do mean mixed) produces a smaller group, the mixed just edged out the matched about 52% to 48%.
Each matched pair was fired through the same gun, randomly, without my knowledge of what case and charge weight I was shooting--as blind as I could easily make it.
I say--It just doesn't matter.
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Old August 9, 2012, 11:42 AM   #32
ROGER4314
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Re Case capacity....I say--It just doesn't matter.

I reload for pistol and rifle and I agree that the internal case capacity of pistol cases is not a major issue.

It's like using match bullets at less than 50 feet. I think it's a waste of money. You can do it if you want to and it won't hurt anything but it won't be a cost effective change for what it gains for you in accuracy.

I have some .45's loaded on a mixed bag of cases right now and that doesn't bother me. Where you see a big difference is in rifle rounds for long range shooting. Some manuals even caution you to watch carefully for pressure signs when charging commercial versus military brass due to differences in internal case capacity.

I wasn't real clear. Thanks for pointing that out. I placed an edit in my initial post.

Flash

Last edited by ROGER4314; August 11, 2012 at 09:47 AM.
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Old August 12, 2012, 09:57 PM   #33
ky hunter
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1: Your powder burnrate and weight of charge needs to be compatable with bullet weight.

2: Case preperation

3: The bullet

THE BREAK DOWN

1: There are different types of powder from ball, extruded, long cut extruded, short cut extruded, spherical, flake, to name a few. All have different burn rates, different compaction, and volume size. In most cases the more volume the powder has in the case, the better the accuracy. the slower the burn rate is, the more pressure behind the bullet. Normally for heavier bullets slower burning powder is used. Keeping a constant amount of powder in each shell is the biggest factor.

2: The most important thing when it comes to case prep for accuracy is in the sizing process. Some neck sized only, some full length size depending on what weapon you shoot. The second most important thing in case prep would have to be trimming the length of the case along with chamfering and deburring the neck inside and out. Then primer pocket prep. next would have to be flash hole prep.

3: What effects the accuracy of the bullet most is the shape. long pointed bullets with boat tails are supposedly better for "cutting the wind". Flat based bullets with round noses are supposedly not as accurate. Then The weight of the bullet because the weight of the bullet determines how wind resistant it is. Then the hardness of the bullet. Harder bullets build more pressure because they don't shape in the barrel and go through it slower than a softer bullet. jacketed lead bullets seem to have the best accuracy because they form to the shape of the barrel when traveling through with less fouling to the barrel. Lastly how the bullet is seated in the case.

4: In my humble opinion, and this is only my opinion. You need to reload each and every gun differently to conform to the guns needs. Some guns shoot better with different powders, bullets ect...

Last edited by ky hunter; August 12, 2012 at 10:02 PM.
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Old August 13, 2012, 08:17 AM   #34
Bart B.
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Too bad most "accuracy" determinations are flawed by us humans' inability to hold, fire and move in recoil exactly the same for each shot. Some are more repeatable than others, but such is life.

Regarding the comment:
Quote:
What effects the accuracy of the bullet most is the shape.
I strongly disagree. Bullet balance is far more important than shape. The more unbalanced they are, the more they'll jump off the muzzle axis as they exit and take a more irregular spiraled path downrange as well as having a greater drag going through the air causing more vertical shot stringing as range increases. Doesn't matter how streamlined or blunt nosed they are; if all have exactly the same shape and weight and are perfectly balanced and leave at the same muzzle velocity in a stable atmosphere, they'll all go in the same hole down range because they all have the same ballistic coefficient for each one. The only difference is the streamlined ones will have less of a trajectory arc to the target than the blunt ones.

Nowadays, there's no significant difference between the best boattail and flat based bullets. Benchresters used to prefer flat based ones for short ranges but seems the boattail ones have finally equalled and often bettered them. It takes a rifle and shooter capable of consistant sub 2/10ths MOA at short range to tell the difference.

Last edited by Bart B.; August 13, 2012 at 12:17 PM.
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