Primer Findings! Am I nutzzzzzz

J

JasonYuke

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Yesterday was a beautiful day , calm winds less than 5km from the south.

I packed up my 6 BR , 6.5x284, my wilson loading gear, chroney and Lap top to run STD dev on my loads, in strings of 3 and 5.

Already have my powders and bullets decided just some fine tune work to do.

I know I have posted before about difference in primers but now I have proof!

I ran 30. gr of varget for 3, 3 shot groups (9) shots over the chroney with CCI BR primers, than teh same with Fed , GMM. There was a huge diff in group size to std dev. The Fed GMM primers are much more predictable and concistant than teh CCI,

I began running different loads from 29.5-31.0 and found teh same with teh sweet spot at 30.0 std dev for the Feds was 10 std dev for the CCIs was 35 and up to 50 with one string, with no other variables becides a primer change.

Groups would open up .2 to .3 with one small pimer change.



As for the 6.5x 284, I found teh same using a 48.0 grain charge of H-4350 and other charges as well, but 48 was the sweet node for the gun, and the Fed GMM proved best again.


I had noticed this before when i switched from Feds to CCI in my Tikka tactical but was suspect until i found my own results I never did shoot the 308 over the chroney but I am sure teh primer upset the ballance. I now know it was a primer change to off set accuracy. If any one ever doubt teh effect of a primer charge, re think and try this for your self. It was a very rewarding day for me.


I do not think teh avg hunting rig would be affected but it sure plays hell on teh BR stuff.

Regards
 
My 6BR Varget loads with CCI BR4 primers usually have SD's of 4-7. Very rarely will I see one go over 8 or 9 over a variety of loads.
 
I guess I did have a few over 10 this weekend :redface:

The chrono data below is from 2 guns and 5 different loads, both used same powder (Varget), cases (Lapua), bullets (Sierra 107's) and primers (CCI BR4)

Strings 1-7 were from a borrowed 6BR and was 4 different loads
Strings 8-11 were from my own and were 2 different loads
(5 loads total as they overlapped)

String 1
1) 2889.0 2.2
2) 2894.0 7.2
3) 2880.0 -6.8
4) 2893.0 6.2
5) 2878.0 -8.8

High: 2894.0
Low: 2878.0
E.S.: 16.0
Ave.: 2886.8
S.D.: 7.4

String 2
1) 2869.0 -5.8
2) 2861.0 -13.8
3) 2873.0 -1.8
4) 2885.0 10.2
5) 2886.0 11.2

High: 2886.0
Low: 2861.0
E.S.: 25.0
Ave.: 2874.8
S.D.: 10.7

String 3
1) 2908.0 8.8
2) 2905.0 5.8
3) 2892.0 -7.2
4) 2888.0 -11.2
5) 2903.0 3.8

High: 2908.0
Low: 2888.0
E.S.: 20.0
Ave.: 2899.2
S.D.: 8.7

String 4
1) 2893.0 -12.0
2) 2896.0 -9.0
3) 2913.0 8.0
4) 2918.0 13.0
5) 2903.0 (ED)

High: 2918.0
Low: 2893.0
E.S.: 25.0
Ave.: 2905.0
S.D.: 12.4

String 5
1) 2891.0 0.2
2) 2898.0 7.2
3) 2874.0 -16.8
4) 2907.0 16.2
5) 2884.0 -6.8

High: 2907.0
Low: 2874.0
E.S.: 33.0
Ave.: 2890.8
S.D.: 12.7

String 6
1) 2852.0 1.8
2) 2848.0 -2.2
3) 2844.0 -6.2
4) 2850.0 -0.2
5) 2857.0 6.8

High: 2857.0
Low: 2844.0
E.S.: 13.0
Ave.: 2850.2
S.D.: 4.8

String 7
1) 2920.0 20.0
2) 2904.0 4.0
3) 2888.0 -12.0
4) 2892.0 -8.0
5) 2896.0 -4.0

High: 2920.0
Low: 2888.0
E.S.: 32.0
Ave.: 2900.0
S.D.: 12.6

String 8 30.5grns with 1.813 Comparator OAL
1) 2875.0 10.6
2) 2862.0 -2.4
3) 2867.0 2.6
4) 2854.0 -10.4
5) 2865.0 0.6
6) 2863.0 -1.4
7) 2861.0 -3.4
8) 2861.0 -3.4
9) 2870.0 5.6
10) 2866.0 1.6

High: 2875.0
Low: 2854.0
E.S.: 21.0
Ave.: 2864.4
S.D.: 5.7

String 9 30.9grns with 1.792 Comparator OAL
1) 2880.0 -5.2
2) 2891.0 5.8
3) 2886.0 0.8
4) 2882.0 -3.2
5) 2887.0 1.8

High: 2891.0
Low: 2880.0
E.S.: 11.0
Ave.: 2885.2
S.D.: 4.3

String 10 30.9grns with 1.813 Comparator OAL
1) 2898.0 -3.2
2) 2898.0 -3.2
3) 2899.0 -2.2
4) 2903.0 1.8
5) 2908.0 6.8

High: 2908.0
Low: 2898.0
E.S.: 10.0
Ave.: 2901.2
S.D.: 4.3

String 11 30.9grns with 1.813 Comparator OAL
1) 2894.0 -2.8
2) 2903.0 6.2
3) 2894.0 -2.8
4) 2890.0 -6.8
5) 2903.0 6.2

High: 2903.0
Low: 2890.0
E.S.: 13.0
Ave.: 2896.8
S.D.: 5.9

(End Of Data)
 
Last edited:
I don't find the CCI BR primers work all that well for large columns of slow burning powder. I sometimes even go to GMM magnum primers for the really slow burning stuff.
 
Nope, the only other primers available around here are Winchester. I bought 6 or 7000 BR4's at WSS last year.

I was going to pick up some Federal Match Primers at the last gun show but people were asking far more than they were worth ($65-$75/1000)
 
Primers

Hi

I have been testing my new 6.5 x 47 Lapua the last 2 days and the difference in accuracy was noticeable depending on the primers used. I tried BR4's, CCI 450 small Magnums, and Federal 205M's. In all combinations of powders, the CCI 450's were the most accurate. I haven't tested the velocity of the loads yet because I find that accuracy doesn't relate much to velocity and extreme spreads (within reason).

Primers in my 308 Win match loads made another huge difference. The group sizes doubled at 300 meters between BR2's and Fed 210's. The BR2's worked the best in this barrel.

In my magnum hunting rifles I just use Fed 215's.

Steve
 
The moral of the story is you have to test the primers with the load/s rifles you are actually going to use them in--the finest accuracy is not found by following a recipe.

44Bore
 
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