A reminder about primers....

[Rich Coyle]

7/8/15 The temp was 70 degrees for the whole session. I figured if it doesn't put three close, I'm finished with that primer. I fired three groups using the Nosler ABLR 129@ 3.408" and IMR 7828 @ 68.0 with three different primers.

The CCI BR-2 produced a three shot group of 1 1/8" so I fired one more. It enlarged it to 1 7/8".
The Remington 9 1/2M primers produce a three shot group of 1 ½" so didn't fire anymore of that one.

The CCI250 Magnum produced a tree shot group of 5/16" and a four shot group of 7/16". The fifth shot opened the group to 3/4". I accept this as a gift from God.

 

[cape cove]

Had somewhat the same thing happen to me in the 80's with my 25/06. The CCI-200 were giving me two distinct groups in every 5 shot group.Either 2 plus 3 or 4 plus 1. Changed to the CCI-250 and brought all 5 together in a nice 1/2 group. Ever since I always consider the primer as an important adjustment component in developing groups.

 

[ShtrRdy]

Rich -- have you tried repeating this?

 

[Rich Coyle]

ShtrRdy,

Many times with a few cartridges. Never found one primer that seems to come out on top.

 

[tmmcampbell]

I never believed the primer made much difference. I had a 300WM built and the smith shot 2 shots that were touching. I have always used CCI 250 so I matched his loads (h1000) with the 250's and shot about a 2" group. Changed powders and was shooting in the .3 & .4. Went back to the H1000 same 2" group. Decided to try his primers and the group shrunk back under .5.
Some guns it does make a difference which primer you use.

 

[codyadams]

Had the same thing in my .260 AI using small rifle primer brass. With RL26 and the 147 eldm, the BR-4 provided the best accuracy and most consistent velocity. Same brass, same powder, switched to the 156 EOL, and was having fits getting consistent velocity with the BR-4, I started with it as it came out on top with 5 different primers and the 147, and the 147 was relatively close in weight. Tried different primers, and the cci 450 cut e.s. from over 50 to below 20 and had an s.d. of 8 (6 shots), and dropped groups from .5-.6" down to .3-.4" @100. So even a simple switch in bullets can make a big difference.

 

[rsmithsr]

accurate guns RESPOND to small tuning changes
a primer is one
a couple thou in seating depth is another

 

[LoneTraveler]

A good lot of primers is the basis of having accurate loads.

My brother got some CCI 250 primers in 1993-94, Getting load developed for 338 WM for a moose hunt. One shot in 5 would fall 4 to 6 inches low right. He was blaming himself. A man at the range had just a chronograph, My brother shot a 5 shot group. 4 shots went in 1" vel. in the 2920 FPS 1 round went out about 5" velocity about 2770 fps.

At present I am in a sweat, Will true Remington Primers be available again.
I have a 223 Rem. load that will shoot 4 shots in 1 hole at 100 yds. 5th shot will make it 1/4" group. With Remington Primers. I have tried Win. and CCI 3/4" to 1" groups.