From: bartb@hpfcla.fc.hp.com (Bart Bobbit)
Newsgroups: rec.guns
Subject: Re: 308 UBR sm primer
Date: 20 Nov 1994 12:02:42 -0500

Remington's .308 BR (benchrest) case with the small rifle primer
pocket has been around since the early to mid 1980s.  It's a
light-weight case of about 157 grains.  Neck wall thickness is
about .011-in; much thinner than most other .308 cases.  Body
and neck wall uniformity has been very good on the ones I've
measured.

When they came out, 'twas was found to be excellent for short-range
use up through 300 yards.  The milder primer proved excellent
and many new highpower competition matches have been won as well
as many records being set with it.  A favorite load is 42 to 43
grains of IMR4064 behind either a Sierra 168 or 180 grain match
bullet.  Test groups at 300 yards have been in the 1-inch range
which is typically smaller than what any case using large rifle
primers have produced.  Most of the accuracy improvement has
been attributed to the small primer which is milder than the
large ones.  

Some interesting observations were soon noted when using small
rifle primers.  Federal 205M primers were tried, but they were
not consistant in ignition; too many hangfires occured.  The
same thing happened when other standard small rifle primers werw
used, such as the Rem. 6-1/2, Winchester and RWS ones, too.  Seems
the Remington 7-1/2 BR primer is hotter than the others and it is
the only one that can be counted on for consistant ignition.

Several folks have used this case necked down to become the 7mm-08
with excellent results.  Every once in a while, a standard full-
length sizing die won't have a small enough neck diameter and the
.308 BR neck won't be sized enough to properly hold a bullet.
It's important to check this before reloading a batch of cases.

I've used these cases for 200 and 300 yard matches with excellent
results.  Their thinner necks do not cause any accuracy problems
in standard .308 chamber neck diameters contrary to what a lot of
folks believe.  Although these cases work well at the shorter 
ranges, their success at longer ranges has been rather skimpy.
Once in a while, someone will get decent results, but not enough
to count on.  It seems that with heavy bullets, the powder charge
just isn't ignited and burned consistantly enough to guarantee
the best results.

BB