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Brass v accuracy

2K views 16 replies 8 participants last post by  UncleFudd 
#1 ·
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im trying to get best loads for my 6SLR for the upcoming F class, SW Nationals.
I loaded 25 rounds of New, Lapua brass and same in new WW brass. Used exact same weight bullets, powder drop and primers and tested at 100 and 200 yds. I'm really surprised at the difference in the accuracy between the brass. The brass all weighed within 1 grain and the VLD bullets are exactly same wt. they are 104.5 gr and are 105 gr bullets.
Also the fired Lapua were quite stiff to lift the bolt for extraction. Winchester's were very slick.
The rounds from ww brass are all tighter at both distances.
I have decided not to take a chance with the Lapua especially when the distances will go out to 1,000 yds. This much difference in spread would be disastrous.
Anyone else ever had this kind of difference when using different brass for exact same loading.
UF
 
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#3 ·
When I used to shoot bench rest in the 1970s I saw a slight difference in brass but nothing as drastic as you are showing. At the time I was also using Winchester and Remington . The Winchester had the edge over the Remington , but it was a small one to say the least. I did ask around and was told that "if you make one change, then you have to fine tune all over again"
 
#4 ·
With my .223 I have several head stamps, and have developed loads for each head stamp. FNM and PPU are very close to the same internal volumes, so I use the same load for them.
 
#5 ·
There is extra spread due to wind and gusts but overall it just seems the groups using WW brass are much tighter.
Just to be sure, I am going to neck size only and use these same brass to see if fireforming will tighten either or both. Won’t be able to load and shoot til Tue or We’d but will post as soon as I get it done.
UF
 
#7 ·
There is extra spread due to wind and gusts but overall it just seems the groups using WW brass are much tighter.
Just to be sure, I am going to neck size only and use these same brass to see if fireforming will tighten either or both. Won't be able to load and shoot til Tue or We'd but will post as soon as I get it done.
UF
If you have an accurate load for full length sized cases and put that same charge in a neck sized case, your groups are going to open up.
 
#9 ·
I did resize them the first time due to changing from standard 243 cases to the 30 degree shoulder of the 6 SLR.
I have had trouble from the beginning with the Lapua brass being difficult to close and now to open even though these were not too difficult to close.

Slayer; Thanks for the info, I had never heard of that.
usually when I full length size (in the past) and fired, I only neck size from then on as I always thought the fire formed brass was supposed to be the most accurate.
I recently read an article that said many of the rifle loaders are full length sizing "every" time now and that their accuracy has improved and they are not seeing any fewer or not many fewer loads per brass.
I will be watching to see the results specifically of these few fire formed brass with just a neck sizing to see if what Slayer says happens.

Thanks All

UF
 
#11 ·
ue to changing from standard 243 cases to
Would be intersting to run them thru the small base die then conform. I had the bolt issue on some 1X military 308 going to 7-08. Once I ran the 308 thru the SB, the 308 was then good and the 7-08 was also good.

I also found annealing helped repeating the consistency. That and using competition shell holders to ensure the same comparative results.
 
#10 ·
Match Shooting all starts and ends with the same thing: uniformity in every detail. That you found one maker or Lot # of brass to out perform the others is expected. Firing them and reloading them will also affect the performance (sometimes for the better) - just be sure that you process all of your most accurate brass exactly the same.
 
#12 ·
It makes sense that fired brass (from the gun being tested) that is shoulder bumped will shoot more accurately as the chances are much higher that the bullet will enter the bore from the case on center if the case holds it centered in the chamber (assuming the chamber is cut on the centerline of the bore). Further accuracy gains can me made by checking and culling the finished rounds for run out using a tool like the Hornady Concentricity tool.

So if the case is centralized in the chamber and the bullet has no run out and the gun has a chamber on the centerline of the bore then near best accuracy can be approached with repeatable results. Of course you have to find the right load the gun likes and the gun has to have adequate bedding and perhaps a floated barrel (an alternative used by bench rest shooters is to glue the barrel to the gun stock (full length) and float the receiver).

This is my opinion and yours may vary. Handloaders much better than me have done it this way with stellar results.

LDBennett
 
#15 ·
All brass are run thru an necho ga and marked and all rounds are run over the horn. concentricity ga for centering while new and put in batches by matched weight within 1 gr and bullets are exact.
The max spread over my magnetospeed crony are 22fps. I am absolutely certain of the bore center line of bore and chamber.
I think the Lapua are just heavier and more difficult to size. We will soon see.
UF
 
#16 ·
New brass is factory sized and is a loose fit in almost any gun's chamber whether it is sized before shooting or not (nothing in sizing can increase the body diameter to a meaningful amount when it starts out smaller than what the sizing die would produce form a fired round). That almost guarantees the case is laying on the bottom of the chamber with an air space above it. That means the bullet nose is not concentric with the bore centerline. Testing with new brass may not represent the best accuracy possible.

When the cases are heavier the case walls are thicker and the case capacity is less. That effects the pressure generated during firing and you must re-develop loads for that heavier brass to achieve best accuracy.

The test described originally is faulty to some degree because of the differences in case volume. Also variation of velocity over several rounds fired from the same load rarely if ever point to the most accurate load. I have no idea why that is but all you have to do is grab a few magazine articles where the delta velocity is listed with group size and see that that is true. I suspect other variation in shooting a cartridge swamps out velocity delta data.

LDBennett
 
#17 ·
LD
Thats why I wonder if the next firing with the fire formed cases will be even tighter for both brass all other things being equal.
I understand a difference due to volume case for case which is why I think the Lapua is somewhat different. The case walls throughout are thicker than the WW.

I have spend countless hrs and rounds working up to what this gun likes and found it is just about equal for either RL19 and H4831SC. And the velocity giving me repeated tightest groups is as close to 3150 as I can get i.e.; the 43 to 43.5 of either. I recently rounded off at 43 gr and the velocity is averaged at 3122.

I guess I was more alarmed of a sudden to see the rounds from the Lapua (which up until this test) I had been using exclusively. This is my first test or use with the WW brass.

Although, going back to the original article on building the 6SLR the guy said he had his best groups and the easiest loading with either Rem or WW and had gone with the WW to weigh etc and use for his first tournament using this rifle. He said he was very pleased as he shot his first "clean" at 600 yds.

He was using a Bartlein barrel as opposed to my Broughton, but he also recommended the 43 to 43.5 of 4831 powder for the best velocity and groups for his gun.

I should get back to my load room Tomorrow and be able to reboot these brass and run the same tests and this time also take it out to 300. I have my own property that will allow me to shoot out to that distance, max without moving my table. Then I also have to see if I can physically get behind the gun to shoot prone. If not I will see if there is an appeal process to allow disabled shooters some other position that will let him compete. Stay tuned and thanks again to everyone for the help and ideas. Another reason reloading is too much fun and interesting and a constant and never ending education.

UF
 
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