Which small rifle primer consistently gets you single digit SD's in 6mm+ cartridges?

[NORCAL50]

Of what little testing I could find published online comparing primers, if what we're concerned with is SD/ES, I see what looks like to me, the same flaw in all tests— the powder charge is the same...

The difference in primers does change the average muzzle velocity from primer to primer, which should put it into a different node, which essentially invalidates the test results IMO.

Maybe I'm wrong, but if you guys can get single digit SD with whatever primer consistently, and there's a good consensus, then it probably isn't worth testing. So vote away.

Consistent: Minimum sample size of 5rnds, and you would expect to see this result on the next 5 shot string 75+% of the time?

 

[Rocketvapor]

Favorite brand sorted to remove high/low outside the mean.

Unless you don't believe velocity is impacted by primer weight (within same brand/lot).

 

[Doom]

To at @Rocketvapor's point.

Most of the testing which is trying to prove a standard deviation variance is flawed in that there is seldom enough data to have any confidence in the differences. Most of those that do are one time tests and do not provide any analysis other than blindly comparing test data. A more informative and verifiable test is actually the one where the goal is to determine if primer weight makes a difference in velocity and based on a number of test I've seen there is no doubt that primer weight does make difference in velocity. It not a stretch to infer then that primer weight will impact standard deviation.

By its very nature standard deviation is a very difficult factor to determine with any confidence due to the way its distribution is affected by sampling. For small samples the probably is that the standard deviation of a variable is going to underestimate the true standard deviation of a population. For instance to have a 95% confidence that the Standard deviation is 10 or less with a ten shot test would require a test standard deviation of 5.5 fps. For 5 shots it's 3.5 fps. These types of deviation are in the normal variations of a given load. To actually have any confidence would require multiple tests with a significant number supporting the assumption that one is better than another.

 

[Slides]

Every group of 7 shots I did starting load pressure testing and a few groups of 10+ rounds in 6BR Norma with RUAG primers was 5/6 fps SD or less on virgin brass. Will try to do a bit more testing but I'm pretty happy with them so far.

 

[diggler1833]

I generally have no complaints about the CCI BR-4.

That being said; I think that one can usually tighten velocities better through attention to detail in their processes.

 

[AllenOne1]

6.5C using CCI 400 primers
20 Shots 6.1 SD
29 Shots 9.8 SD
19 Shots 6.7 SD
4 Shots 7 SD
39 Shots 8.5 SD
24 Shots 5.9 SD
16 Shots 6.1 SD

I need to work on tightening up the velocity consistency but the numbers are getting there. At this point I'm assuming I may have an odd case or two that are throwing off the numbers. Should check case volumes but that seems like a lot of time and work.

 

[FNG1001]

interesting how the fed 205 gets very little love, yet their 210 is always sold out in minutes of being available

 

[straightshooter1]

interesting how the fed 205 gets very little love, yet their 210 is always sold out in minutes of being available

It's probably because the 205's have such a thin cup??? They're thinner than CCI 400's by .001"and 205M's are just a little thicker my .025". Those thinner cups can be an issue where one sees pierced primers.

 

[Doom]

Every group of 7 shots I did starting load pressure testing and a few groups of 10+ rounds in 6BR Norma with RUAG primers was 5/6 fps SD or less on virgin brass. Will try to do a bit more testing but I'm pretty happy with them so far.

6.5C using CCI 400 primers
20 Shots 6.1 SD
29 Shots 9.8 SD
19 Shots 6.7 SD
4 Shots 7 SD
39 Shots 8.5 SD
24 Shots 5.9 SD
16 Shots 6.1 SD

I need to work on tightening up the velocity consistency but the numbers are getting there. At this point I'm assuming I may have an odd case or two that are throwing off the numbers. Should check case volumes but that seems like a lot of time and work.

In case my post could be misinterpreted these cases show what can be referred to as anecdotal evidence and because the number of rounds is substantial and repeatable it shows very consistent reloading.

 

[NORCAL50]

In case my post could be misinterpreted these cases show what can be referred to as anecdotal evidence and because the number of rounds is substantial and repeatable it shows very consistent reloading.

I think it also shows that primer choice probably doesn't matter as much as other more important variables.

And to your original point, since many different primers are capable of single digit SD, it would indeed be very difficult to show through testing which primer yields the lowest SD with any statistical significance.

EDIT: Added bold font.

 

[straightshooter1]

I think it also shows that primer choice probably doesn't matter as much as other more important variables.

And to your original point, since many different primers are capable of single digit SD, it would indeed be very difficult to show through testing which primer yields the lowest SD with any statistical significance.

Since ignition is such an import part of "precision" shooting, primers can be just as important as picking the right powder. Certainly, they ignite powders differently as can be seen here:

Primer Flash Test Photos

6mmBR.com is the best guide for 6mm BR Benchrest precision shooting, complete with 6BR FAQ, Reloading Data, Shooter Message Boards, Reader Polls, and Photo Gallery. Match event calendar and rifle competition accuracy training tips. Equipment reviews (.243 bullets, 30BR cartridge, 6mm Norma...

www.6mmbr.com

 

[NORCAL50]

Since ignition is such an import part of "precision" shooting, primers can be just as important as picking the right powder. Certainly, they ignite powders differently as can be seen here:

Primer Flash Test Photos

6mmBR.com is the best guide for 6mm BR Benchrest precision shooting, complete with 6BR FAQ, Reloading Data, Shooter Message Boards, Reader Polls, and Photo Gallery. Match event calendar and rifle competition accuracy training tips. Equipment reviews (.243 bullets, 30BR cartridge, 6mm Norma...

www.6mmbr.com

Very interesting photos, thanks for sharing those. Surprised to see such a big fireball from Remington compared to CCI/Federal

 

[FNG1001]

photos seem to be from 2005. Still interesting though, but I would think a few things have changed since then

 

[kthomas]

All I've used for SRP's is CCI BR4 's, and they have worked very well for my applications (6BRA and 6.5 Creedmoor).

Single digit SD's isn't an issue. IMO, I think it's also important to have consistent primer seating depth. In my experience, I find seating primers as deep as reasonably possible obtains the best results.

 

[Rocketvapor]

Does the age and storage history of primers impact brisance ?
OR,
are they made from those forever chemicals that don't degrade with time, temperature?

 

[LR1845]

All I've used for SRP's is CCI BR4 's, and they have worked very well for my applications (6BRA and 6.5 Creedmoor).

Single digit SD's isn't an issue. IMO, I think it's also important to have consistent primer seating depth. In my experience, I find seating primers as deep as reasonably possible obtains the best results.

I've played with primers a lot and have found the same thing....a consistent "crush" for sake of a better word...seems to produce better numbers.

 

[DHDeal]

Whew, what a question. It seems this is another issue like barrel cleaning and/or barrel break in techniques.

Depending on case (caliber, case volume, flash hole size are examples) I will say a CCI450 is my go to. It is my go to because my stash of Wolf SRM is finite though still large. Also mentioned was "crush" and I find with Wolf SRM'S this particular issue is most important. Also for me primer pocket depth may play a small part as I try to make all loaded rounds the same as I possibly can. I just chronographed some 6mm ARC loads (using Lapua reformed cases with the small flash hole) that gave me a 5 SD over 4 - 5 shot groups using CCI450's and AA2520. Shot like shit and it wasn't me....

 

[Cody S]

I typically just use 205m because I had a bunch but I've had good luck out of br4 and 450s as well. the magnum can change load dev a slight bit, easy to correct for ime.