November 15th 2022Vertical dispersion test — Six primer types tested at 500 yards. Do primer types make a significant impact on accuracy or vertical dipersion at long distances? The answer is “maybe”. Here’s an anecdotal example of a study that measured vertical variance between six different primer types. The tester is a skilled shooter and has a very accurate rifle. Four of the six 4-shot groups were below 2. at 500 yards. Although this test doesn’t answer the question, it does suggest that you might try a few primer types with your match ammunition. Forum member James Phillips, an accomplished long-range benchrest shooter tested six different primer types from three manufacturers. James set his target at 500 yards to determine vertical dispersion. Then, he shot four shots groups with each primer type. A chrono was used to record velocity. The results are shown in the photo above. James states that he will retest the two best groups for consistency and accuracy with 10 shots each. CLICK HERE to see the full-screen target photo. As you can see, all the groups are quite impressive. CCI 400 primers were used to capture the smallest group, 1.253?. CCI BR4, which was 1.275?, was next best. for four shots. The Remington 7.5, located at the upper left, was the “flat line” winner. There was almost no vertical. This primer test is worth your attention. 4 shot 2955 FPS 8 FPS 4.0 FPS Federal 205M 2.200? 4 shot 2951 FPS 11 FPS 4.8 FPS Sellier Bellot SR 1.673? 4 shot 2950 FPS14 FPS 5.9 FPS 450M 2.341 4 shot 2947 FPS14 FPS 6.6 CCI 400 1.253 4 shot 2950 FPS3 FPS 1.3 FPSCCI BR4 1.275 4 shot 2949 FPS 3 FPS 1.3 FPS CCI BR4 1.275? 6mmBR Norma is the parent case. The 6 BRA is fired-formed to create a 40 degree shoulder and less body taper. The neck is longer than a 6mm Dasher, but the capacity is higher. This capacity is sufficient to reach the accuracy node at 2950+ FPS. Some shooters believe the 6 BRA is easier to fire-form than the 6mm Dasher. The 6 BRA is definitely easier to fire-form. 6 BRA (40?). TEST REPORT — Conditions. Shooting Method. Loading Method. This report was posted by James Phillips in our Shooters Forum.
Conditions: Testing was done over flags in the morning. The flags were not moved or twitched. I was blessed with the best conditions. It was overcast so there was no wind or mirage. There were only me and the other shooters. Test Procedure: Each shot was shot at my own pace, and was centered using my Nightforce Nightforce 15-55X scope. I didn’t use the round-robin technique. Each four-shot group of the same was shot at once. The primer was then followed by the next. Everything felt perfect for every shot today. I could easily repeat the test tomorrow, and it could be exactly opposite to today’s. This can be pursued forever. How Rounds Were Loaded? Each load was weighed to one (1) kernel powder. So I know that they are as accurate as I can weigh them. Previous Initial Load Test: All groups were shot using 31.1 grains H4895. To complete everything, I used the Sellier & Bellot primer for initial load testing. It was more promising than the CCI 450 Magnum that I tried. It was quite surprising to see the primer’s higher ES, SD, and vertical. [Editor] Take a look at the CCI 450. One shot is in the middle black diamond. This extends the vertical. The vertical was almost non-existent in the Rem 7.5, however. ]Velocity & NODE Considerations: I was 5-6 FPS over what appeared to be my optimum velocity at 2943-2945 FPS. I’ll test 5 shots from 31.0 and 5 from 31.1 and see where it goes. My velocities were higher because of the higher humidity, and also because it was 5 degrees warmer this morning. It was not far away, but I noticed it.
Similar Posts:Tags 6 BRA, 6mm Brahma, BR Ackley Federal Primers CCI Primers Federal Primers James Phillips Long Range Testing Rem 7.5 Primers Vertical Dispersion
