Fed v Win brass accuracy difference with pics

[mram10]

Thought this was interesting today. I shot 2 groups of 5 at 300yds with a generic load. Only difference was the first group was fc brass and the other was win. The orange ear plug was to cover a sighter.
Rifle:7-300wm, 168 vld, 74 h1000, wlrm, 2.610 brass, .005 off lands

 

[spife7980]

So youre telling me that two different types of brass arent identical?

 

[retired]

i think he is proving that different makes of brass have different volumes and thus require SPECIFIC loads.
maybe this is why quickload list each maker of 300 win mag brass separately.

So youre telling me that two different types of brass arent identical?

 

[MagnumManiac]

Totally unsurprising to me.
Have seen the same shooting re-formed 375H&H Remington in 375 Weatherby against Weatherby factory brass.
Have also seen the same using Win 22-250 in 22-250AI against re-formed Lapua.
Internal shape is as big a part in changing ballistics as is the actual volume difference.

I never mix headstamps and try to keep lots separate also.

Cheers.

 

[Bart B.]

So youre telling me that two different types of brass arent identical?

I've had 308 and 7.62 brass weighing 150 to 190 grains. A few thousandths spread in wall thickness is the main cause. With 5% reduced loads at the same charge weights, they shot equally as accurate.

Those pictures show the large group is over twice the size as the small one. I don't think that's the norm with the same load in two case weights a dozen or two grains apart.

A few thousandths inch spread across different chamber's diameters cause the same iissues

 

[ireload2]

I have often seen the same variation with the same exact load in the same exact brass.
If you repeat the test 25 times you will have statistically valid results. One pair of groups is only a coincidence.

 

[mram10]

No pics of brass since I already prepped it for the next trip to the range. Argue stats all you want, but it was a large enough difference to prove it to me. 25 more tests isn’t enough to prove it to some. I just wanted to share my finding with pics rather than just a quick post.

 

[ireload2]

In god we trust all others must bring data. 2 groups proves nothing.

No pics of brass since I already prepped it for the next trip to the range. Argue stats all you want, but it was a large enough difference to prove it to me. 25 more tests isn’t enough to prove it to some. I just wanted to share my finding with pics rather than just a quick post.

 

[shoot4fun]

No pics of brass since I already prepped it for the next trip to the range. Argue stats all you want, but it was a large enough difference to prove it to me. 25 more tests isn’t enough to prove it to some. I just wanted to share my finding with pics rather than just a quick post.

I would not ever question that there could be a difference in accuracy due to brand of brass (all other components being same). I will ask if both brands in your test were virgin brass and equally prepared. This "test" could have gone the same way with two lots of the same brand; for that matter with two groups of brass from the same lot and box.

 

[Doug Beach]

To the OP: what exactly did you learn?

 

[Dusty Stevens]

Work up the best load in each set of brass and i think youll see a different result. This is like the guy comparing the anschutz to the cz shooting the same ammo in both which probably wasnt the best ammo for either one. Shoot a group with those 168vld and try the same load with a 155 and let us see the results.

 

[people]

Not surprising at all. Brass varies from even the same manufacture. There is a reason why the gov states how ammo is loaded pertaining to lots of components.

While some producers are very consistent over the years Their brass does varies from year to year.

 

[Bart B.]

Argue stats all you want, but it was a large enough difference to prove it to me.

Which consecutive 5-shot group in this composite of fifty-four of them is the smallest and largest?

If you ever look at the 5-shot group results of a benchrest match, each competitors' groups easily have up to a 6X or more spread in size.

 

[243winxb]

Brass varies from even the same manufacture.

Sure does.

When the loaded rounds neck diameter closely fits the chamber, accuracy was much improved.(factory chamber)

New Win brass neck diameters, in 243 was right at .276" when loaded. All other lots were less and were not as accurate. (Rem 40xb)

This is the strange part, using standard RCBS FL die. (before bushings).

After each loading, the loaded rounds neck diameter decreased and so did the accuracy. After a set amount of loadings, the neck wall thickness stopped thinning. The over working of the brass by the die/expander unit thinned the neck case walls.

 

[M-61]

I would do a lot further testing.

There are days I shoot and the groups are fabulous.
There are days I go where it is a disaster.
There are days I go where the the 1st groups are not good at all. Then the last groups are great.
And this is all with the same brass with same loads and of course the same rifle.
Still trying to figure out why I am not the same!

 

[Bart B.]

After each loading, the loaded rounds neck diameter decreased and so did the accuracy. After a set amount of loadings, the neck wall thickness stopped thinning. The over working of the brass by the die/expander unit thinned the neck case walls.

People have reloaded the same 308 Win case over 40 to 50 some odd times. Had to trim it every 10 shots. Both used a standard RCBS full length die, gelded, neck honed out to .002" smaller than loaded round neck diameter. Dies set to bump fired case shoulder back one to two thousandths.

One with hunting bullets put all shots in 5/8th MOA, the other with match bullets put them inside 3/8th MOA. Yes, necks probably thinned a bit. Not enough to change accuracy. SAAMI spec chamber in both barrels.

 

[Bart B.]

When the loaded rounds neck diameter closely fits the chamber, accuracy was much improved.(factory chamber)

What is "closely fits?" Less than .001" clearance all the way around?

New cases with at least .005" clearance to 7.62 NATO MIL SPEC chamber necks .3445" +.020" diameter had no problems shooting good match bullets inside 2/3rds MOA at 600 yards testing for accuracy.

I've not seen any proof that small clearances from rimless bottleneck chamber neck to case neck does anything to center bullets on the bore axis when fired. Having measured different case's necks clearance to a chamber neck in firing position, they all centered very well. A .243 Win case neck centered perfectly in a 308 Win chamber.

If the case neck axis is off the case shoulder axis, it and its bullet will never center in the chamber when fired regardless of clearance amount.

Belted cases headspacing on their shoulder behave the same. New belted cases of good quality typically center their neck and bullet in the chamber. Their shoulder and neck not touching any part of their chamber.

 

[dmoran]

If you ever look at the 5-shot group results of a benchrest match, each competitors' groups easily have up to a 6X or more spread in size.

This is another falsified statement your making. The winning aggregates in today's world prove your statements to be no more then a coercion of truth and reality.

What involvement do you personally have in benchrest to base your inputs from?
List the BR sanctioning's and the matches your basing your statements from.
And list the actual BR matches you yourself have attended.

 

[Bart B.]

This is another falsified statement your making. The winning aggregates in today's world prove your statements to be no more then a coercion of truth and reality.

Of course they do.

I referred to all competitors' groups, not just the winners.

My remark "each competitors' groups easily have up to a 6X or more spread in size" is one you misconstrued. "up to 6X" includes all from zero to six times.

Winners' groups are in the 2X spread range. Which is in the lower third of, and therefore part of, a 6X range.

 

[dmoran]

Of course they do.

I referred to all competitors' groups, not just the winners.

My remark "each competitors' groups easily have up to a 6X or more spread in size" is one you misconstrued.

Winners' groups are in the 2X spread range. Which is in the lower third of, and therefore part of, a 6X range.

Again, list the BR sanctioning's and the matches your basing your statements from.
Show the actual results that your basing the: "easily have up to 6X spread" inputs of yours from.