When I was shooting HBR rifles, I used to weigh the brass, turn the necks and uniform the primer pockets and flash holes in an attempt to gain ultimate accuracy.
Later, as I was getting out of the game I tried about 50 cases of mixed commercial and milsurp brass. I had to turn the necks and trim to length so they would fit in the chamber but that was it. The brass was re sized in Bonanza small base Match dies then loaded with a Wilson press. I used the same load of W748 under 135 grain flat based Bergers with CCI BR2 primers. The results startled me. There was little if any difference to the painstakingly prepared brass.
Now, let me take the experiment a bit further. I then reloaded the mixed lot of brass with the same components but just used the Bonanza die set in an RCBS Jr press. There was a significant difference this time in many ways. The first was bullet run out. Not a lot but about .006 on average with the worst as much as .010.
When shooting the bullet with .006 and less run out, accuracy was on par with the cartridges loaded on the Wilson press. This is where things went awry, When the cartridges with up to .010 run out were fired, the groups opened up from .325 at 100yds to .970.
The rifle in question here was a full sized Mod 700 Rem short action with jewel 2oz trigger, bedded properly and put together by Nobby Uno with a Match Grade "Hart" barrel with 1-15 twist and was chambered in 308Win. I wanted more velocity to shoot the 135 grain bullets in the cross winds without haveing to hold off so much for windage. 6X Burris swcope was used.
I then used the same cases/components in a Rem 700 SA, hunting rifle. The rifle was an off the shelf specimen without any frills. I went through the whole process all over again. This time, the results weren't significantly different from the previous test. The groups opened up of course. The Wilson press groups averaged .900 on the button with only one flyer that was totally unexplained out to 2.65. The Bonanza dies performed about the same as before with similar run out. This time the group opened up to 1.350 inches.
The problem with the Bonanza dies causing run out was caused by the bullet seater. It was just to sloppy because it didn't fit the ogive of the bullet properly. The chamber in the factory rifle was a lot more generous and the throat was deeper than the HBR rifle as well, which gave, IMHO, to much fee bore and effected accuracy.
There are many things that will effect your accuracy, inconsistant bullet jacket thickness, throat depth/wear, powder, twist rate, bedding and alignment of the loading equipment used. That's just the beginning.
If you're using your rifle for hunting, groups at 100yds that are less than 1 1/5 inches are fine. If you're not going to shoot more than 300yds, about maximum for most, even 2 inch groups ar OK. Getting the bullets to the proper place on target is up to you.
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