From: bartb@hpfcla.fc.hp.com (Bart Bobbit)
Newsgroups: rec.guns
Subject: Re: picking brass for accuracy
Date: 15 Nov 1994 17:18:52 -0500

Bulbospongiosus (loki@acca.nmsu.edu) wrote:

: So what does one measure on brass when one is picking some out for
: accuracy work?  And how does one go about measuring these things?

Getting uniform brass for accuracy work will take up to 1/4 to 3/8 MOA
off of the groups the shooting system (rifle, sights, ammo and shooter)
can produce at 100 yards.

There are 4 areas of brass uniformity that seem to help the most:

  * Uniform neck and body wall thickness.  Should not have a spread of
    more than about .002-in.  Turning necks to less than .001-in.
    spread will help somewhat when tight-neck chambers are used; it is
    not needed for factory or other standard chamber neck diameters.

  * Flash holes centered in the case and of uniform diameter, plus
    being deburred on the inside.

  * Primer pockets uniformed to the same depth.

  * Case weight varies no more than 1%.

But new, never fired, factory cases that have none of the above stuff
done/checked can easily produce 1/4 to 1/3 MOA groups at 100 yards, if
the rifle is built with all the right stuff put together the right way.

One great deterrent to accuracy with factory rifles is the bolt face is
usually not square with the chamber.  After each fired case is reloaded,
its out-of-square head presses at a different point on the bolt face.
That can easily mask all of the above brass uniforming efforts and make
things appear like uniforming ones cases doesn't help at all.

Using the right primer, powder and bullet will probably show a greater
accuracy improvement with factory rifles than uniforming cases.  And
changing the reloading process can often show accuracy improvements
more drastically than just uniforming cases.

In the grand scheme of things, I'm convinced that uniform cases is quite
a ways down on the list of priorities of attining accuracy.  It it
wasn't, then all the folks who shoot 1/2 MOA groups at 100 yards without
going through the case uniforming process would not do what they do.

RCBS's Casemaster is a good tool.  Other, more sophisticated ones are
available from dealers catering to the benchresters.

BB

From: bartb@hpfcla.fc.hp.com (Bart Bobbit)
Newsgroups: rec.guns
Subject: Re: Match brass, where to get?
Date: 28 Nov 1994 11:20:38 -0500
Lines: 14

Military brass, even the match stuff, is not nearly as uniform
as commercial brass.  Winchester's .308 Win. Palma brass is
about the most uniform brass around.  Remington's .308 BR brass
with the small primer pocket is also excellent and is great for
use at 200 and 300 yards.  Regular Federal brass is also good.

I would think that if your objective is best accuracy, you would
want to use brass capable of achieving that objective.  Military
brass is not preferred when accuracy is paramount.

BB

From: bartbob@aol.com (Bartbob)
Newsgroups: rec.guns
Subject: Re: Q's about 308 match brass
Date: 1 Jan 1996 16:40:24 -0500

The best brass ever made for use in the .308 at ranges greater
than 600 yards was made in 1958 by Western Cartridge Company
for the US International Team's 300 meter matches.  It was the
most uniform in wall thickness and also the lightest (150 grains.)

As uniform wall thickness is probably the most important thing
to look for in brass for long range use, getting decent brass to 
start with is important.  Winchester's Palma cases are probably
the best available at this time for new cases.  Weighing about 166
grains each, they have neck wall thickness variations of less than
1/1000th of an inch; plenty darn good indeed.  This brass was used
in the 1992 International Palma Matches with excellent results for
factory ammo.  Test groups at 600 yards were in the 3 to 3.5 inch 
range.  Not bad at all for new cases.

Stay away from military brass.  The best of it is LC match cases, but
even that stuff is horribly non-uniform in wall thickness in addition to
being too heavy prohibiting heavy enough powder charges to be useful.

Lapua and RWS brass is also rather heavy which limits the powder 
charge weight.  Besides, it costs a lot more than Winchester Palma
brass and doesn't shoot nearly as accurate.

Remington BR cases using the Rem. 7-1/2 primer works well up to
300 yards with reduced loads, but results with max loads at long range
hasn't yet consistantly equalled Winchester brass.

Federal brass isn't quite as uniform in wall thickness as Winchester's
Palma brass.

BB