Causes of extream spread

[billlarson]

How many long range competitive shooters cut that last tiny particle of powder to a fraction of its size to get charge weights uniform to 1/50th grain? Wouldn't that be hard to prove with a cartridge which typically has a 6 to 7 fps change in muzzle velocity for 1/10th grain change in charge weight?

Never heard of such meticulous detail in ammo loading. Especially when I and others have shot 308 Win ammo with .003" bullet runout in new, unprepped cases with a 4 grain spread in weight, 3/10ths grain charge weight spread that shot about half MOA at 600 yards. In a few dozen barrels with different shapes plus different bore, groove and chamber dimensions.

1) most guys who shoot LR weigh to these extremes..... go to a match and ask .... how they are weighing powder.....
2) the loads you just described will not shoot .5 MOA at 1000 yds....
bill

 

[dmoran]

@Bart B.
In testing conditions with my pet loads, would estimate +75% of the time.
And almost always or very high percentage of the time within 1/3-MOA vertical.

Personally I would never expect 1/2-MOA agg's at 600 or farther from those kinds of tolerances you quoted.
But maybe just me
Donovan

 

[Bart B.]

) the loads you just described will not shoot .5 MOA at 1000 yds.

I agree. They shot about .75 MOA.

I'm not aware of any rifle that shoots inside .5 MOA at 1000 all the time. Occasionally, sometimes or rarely, yes

 

[dmoran]

I'm not aware of any rifle that shoots inside .5 MOA at 1000 all the time.

@Bart B.
The best one I know of is the current IBS1000 Champion's (@tom, aka: Tom Mousel ) who has a LT-Gun that has a 36 target agg of 3.4119" at 1000yds. Its best group 1.875" and worse group was a 7.007".
His loading tolerances are tighter then mine... lol
Donovan

 

[ebb]

Does anyone really know if the first 40 grains of powder in the jug produce the same energy as the last 40 grains in the jug? Are all the kernels in the jug the same length? It is my understanding that the amount of surface area of a kernel gives it its burn rate, do all the kernels have the same surface area? When they cut H4831 SC does some one measure each kernel with dial calipers to see if they are the same? I guess my point is with all the variables in the case, the bullet, the primer, the powder, the ect , the ect. its a wonder anything ever gets hit way off. One real good match shooter says he weighs cases the next says it a waste of time. One says he measures bearing length the other says no. There is too much opinion and not enough cold hard fact. If we as shooters could pool our resources and fund some one to test some of the ideas as to what works and what doesn't, then I could get into this super precise reloading regimen. But when no two shooters believe the same thing, I am not changing. Don't get me wrong I would love to make better ammo but who do you believe?

 

[Bart B.]

LT-Gun that has a 36 target agg of 3.4119" at 1000yds. Its best group 1.875" and worse group was a 7.007".

Thanks for that. Why doesn't it show up in:

http://internationalbenchrest.com/records/long_range/1000.php

His 2026 record agg shown is 4.3155" for 10 targets

Short range agg's also have about a 4X spread in group sizes; often more. My ruler says he's got a 7/10ths MOA system. That's about as good as any 1000 yard system has.

 

[Joe Salt]

There is too much opinion and not enough cold hard fact. If we as shooters could pool our resources and fund some one to test some of the ideas as to what works and what doesn't, then I could get into this super precise reloading regimen. But when no two shooters believe the same thing, I am not changing. Don't get me wrong I would love to make better ammo but who do you believe?


ebb: That's a great Idea but no two rifles are the same, just because it works in my rifle doesn't guarantee it will work in yours. Sorry but there is no magic bullet, you are going to have to work for it. And you will burn yourself out trying keep things perfect. Just try one thing at a time. If it doesn't work go back and try something else. Do not try 5 things at a time and think you have the answer.

Joe Salt

 

[Shynloco]

One says he measures bearing length the other says no. There is too much opinion and not enough cold hard fact. .....

Personally I love these types of discussion (and appreciate the thought provoking ideas) as many of those commenting, have both the background and history to know WTF they are talking about. The rest are opinions and fall into the category as ebb puts it, varying opinions never end, depending on who you talk to, and that's even from the folks lining up and shooting at serious competitions. But in the end, all the ideas seek that final result of what works best for you and particularly your PARTICULAR rifle. For over the years, I've listened to the ideas of one EXPERT MARKSMAN and found they don't produce the excellent results that another EXPERT MARKSMAN has and his/her approach to solving the issue at hand. And it's not the idea, its how a specific rifle shoots when applying the advice given. And my favorite, is the varying ideas of how to solve the never ending challenges of the VARIABLE we can control and even the basic identification of those VARIABLE at times.

So keep it coming guys. I so thoroughly enjoy hearing from all the EXPERTS because it makes me stop and think about the things I perhaps have missed or can improve upon. Great job done by all to hopefully promote new thinking in the vast areas that interconnect reloading with accurate shooting. Thx guys!

Alex

 

[dmoran]

Thanks for that. Why doesn't it show up in:

http://internationalbenchrest.com/records/long_range/1000.php

His 2026 record agg shown is 4.3155" for 10 targets

@Bart B.
Those 10 were not all shot with the same rifle.
It (Tom's "Hot Gun") and its pet load, life time (36) is 3.4119" @ 1000

 

[Bart B.]

. But when no two shooters believe the same thing, I am not changing.

I'm convinced that if everyone used the same conditions and standards for accuracy (precision?), the methodology would narrow down.

I measure and claim a rifle's ability to put bullet holes as close together as possible as the circle size encompassing all shots fired. Not the average of some number of a few, several or many group sizes. All shots. Smallest few shot groups don't reveal how big the variables can add up to. They show what happens when all are near zero or perfect. They also show how variables cancel each other out. How do you know which one?

 

[Bart B.]

Those 10 were not all shot with the same rifle. It (Tom's "Hot Gun") by itself life time (36) is 3.4119" @ 1000

Best info chunk I've seen in this thread.

Here's what my 30-338 did shooting 190 and 200 grain Sierra's alternately to see how each would do over 30 shots. Fired once every 25 seconds or so. Barrel really got hot.

190's from once fired FL resized unprepped cases. 200's from new cases but neck turned to .012" walls.

Shot slung up prone with a rice bag under fore hand under fore end and stock toe. Pit crew said both 15-shot groups were about 4.5 inches.



Still have the rifle with the 30" barrel that did that. Any offers?

 

[dmoran]

Best info chunk I've seen in this thread.

@Bart B.
Been trying to buy that barrel from him... but he keeps telling me no lol

 

[Alex Wheeler]

I would say most of the Lr Br guys are weighing to the kernel. I know I weighed to .02. Of course .02 in a case that takes 33 is different than .02 in a case that takes 50 grain or more.

 

[Link]

Personally I love these types of discussion (and appreciate the thought provoking ideas) as many of those commenting, have both the background and history to know WTF they are talking about. The rest are opinions and fall into the category as ebb puts it, varying opinions never end, depending on who you talk to, and that's even from the folks lining up and shooting at serious competitions. But in the end, all the ideas seek that final result of what works best for you and particularly your PARTICULAR rifle. For over the years, I've listened to the ideas of one EXPERT MARKSMAN and found they don't produce the excellent results that another EXPERT MARKSMAN has and his/her approach to solving the issue at hand. And it's not the idea, its how a specific rifle shoots when applying the advice given. And my favorite, is the varying ideas of how to solve the never ending challenges of the VARIABLE we can control and even the basic identification of those VARIABLE at times.

So keep it coming guys. I so thoroughly enjoy hearing from all the EXPERTS because it makes me stop and think about the things I perhaps have missed or can improve upon. Great job done by all to hopefully promote new thinking in the vast areas that interconnect reloading with accurate shooting. Thx guys!

Alex

Well written Alex, my feelings also.

Link

 

[Bart B.]

Here's what IMR4895 charges averaging 45.3 gains with a 1/10th grain spread did shooting Sierra 155's out of unprepped WCC60 308 Win match cases with RWS primers at 800 yards:



Hole numbers 1 and 2 were the first and second shots fired. Earlier tests with chronograph showed clean barrels shot the first couple bullets about 15 to 20 fps slower than the rest. More fouling increases resistance and pressure to shoot them faster?

 

[dmoran]

I'm convinced that if everyone used the same conditions and standards for accuracy (precision?), the methodology would narrow down.

I measure and claim a rifle's ability to put bullet holes as close together as possible as the circle size encompassing all shots fired. Not the average of some number of a few, several or many group sizes. All shots. Smallest few shot groups don't reveal how big the variables can add up to. They show what happens when all are near zero or perfect. They also show how variables cancel each other out. How do you know which one?

You being a for score highpower shooter with every shot marked/spotted, I can see why you assess as you do.
Bare in mind in LR-BR, we shoot with out spotter, and are blind to where we are impacting the target in our record strings, with the group size taking precedence over score.
Two different games with two different demands for precision and assessment.
Donovan

 

[dcali]

Not exactly an answer, but things that reason would tell you that impact ES:

-variation in bullet weight
-variation in charge weight
-variation in powder chemistry
-variation in primer impulse (not sure what the techinal term is here)
-variation in case volume
-variation in powder temperature
-variation in barrel fouling
-variation in barrel wear
-variation in barrel temperature
-variation in starting pressure (bullet release and engraving force):
--variation in bullet jacket thickness/hardness
--variation in bullet jump/jam
--variation in neck grip

Now, there's not a lot that we can do about all of these, but there's something that can be done about some of them. I just wish I knew which ones matter most.

 

[Bart B.]

I've shot 1K yard bench rest matches and scoped every shot hole after it went in. While not the norm, it can be done with a good spotting scope in decent conditions.

Bullseye shooters in rapid fire matches can scope the first two or 5 shots, then hope the next eight or five in a 10-shot match go where those two went; if they're centered, if not crank the sight knobs after reloading then shoot again.

But I want the best ammo precision possible. I want bullets to strike as close to call as possible as does all the other bullseye busters. Even if it's way out in the 8 ring at 3:30 on the clock. Your group on the bullseye will be smaller with the most accurate ammo possible. Bullseye groups are always bigger than what the rifle and its ammo can shoot; a fact of life with hand held rifles fired without artificial support.

Of course they're different games. But best accuracy of stuff you're using is always the objective. Bullseye rifle shoot their bullets just as accurate as BR rifles do. But it takes a machine rest they're clamped into because their stocks are not designed for free recoil shooting as they rest on artificial support. The best of them shoot inside 6 to 7 inches at 1000 like the stool shooter's stuff does.

The NRA 1000-yard scope sighted rifle record shot prone on a bullseye target is 20 shots scoring 200-19X. Nineteen shots went into the 1 MOA 10" X ring, one leaked out about an inch into 10-ring. The rifle tested about 1/2 to 2/3 MOA with the 300 Win Mag ammo used.

 

[Alex Wheeler]

Your saying you shot a 1k br matches and looked at each shot with your spotting as you shot them during the match?

 

[Alex Wheeler]

I am afraid I have been lost with the plotting shots. Once in my life I could plot individual shots in the white. With absolutely ideal conditions and a $4k Swaro. I have serious doubts in those claims. No matter, if its working in your game that is all that matters.

I have been racking my brain. I know its a little different question than the op, but how is it, everything being equal and loaded to the same precision that one powder charge will produce good es and other wont?