Regular vs. MilSpec vs. Magnum Primers

[Hypnogator]

I have been reading conflicting information on using regular vs. MilSpec vs. Magnum primers in loading for .223 in the AR Platform. A couple of months ago, I bought a carton of CCI-41 primers, which seemed to be actually giving a slightly lower average velocity than regular CCI-400s. Finally, a week ago, I managed to find a box of CCI-450 primers, so I decided to test the three types of primer.

To test the primer variance, I loaded 30 rounds of .223, using new Lake City cases with 25.0 gr. AR-Comp under a Hornady 55-gr. V-Max bullet. Ten of the cases were primed with CCI-400s, ten with CCI-41s, and ten with CCI-450s. All charges were weighed on my new digital scale. I shot them this afternoon, recording the velocities with my new (to me) CED Millennium chronograph with the following results:

The CCI-400 standard primers gave an average velocity of 3054.40 fps, with a SD of 19.31.

The CCI-41 MilSpec primers gave an average velocity of 3068.90 fps, with a SD of 13.83.

The CCI-450 magnum primers gave an average velocity of 3054.60 fps, with a SD of 11.01.

In this test, the MilSpec primers proved slightly hotter (but only by 14 fps) than either the standard or magnum primers, and the magnum proved to be the most consistent.

As a check of my chronograph under the same weather conditions (mid-60s) I fired 10 rounds of Wolf Gold 55-gr. .223, which averaged 2982.80 fps, SD 28.09, and 10 rounds of Carl Gustav 62-gr LAP 5.56mm, which averaged 2980 fps, SD 12.82.

It would seem to me, that at least with AR-Comp powder, there is little difference between the three types of primer in terms of velocity, and virtually no difference between CCI standard and magnum primers.

FWIW

 

[ArchAngelCD]

According to CCI ...

Their CCI-400 primers are standard small rifle primers.
Their CCI-450 primers are their magnum strength small rifle primers.
Their CCI #41 NATO primers are magnum strength primers but the primer compound isn't as sensitive as the compound in their standard or magnum strength primers.

Since the #41 primers are magnum strength I'm surprised the results for the #41 and 450 primers weren't more similar.

Thanks for the inf from your tests...

 

[Walkalong]

Run the same test another day and it may turn out different. 14 FPS isn't much, and ten rounds isn't a big sample.

That said, I use 5, 6, and 7 round samples all the time. I just realize the results are not set in stone. It does however, give me a good indication of what to expect. When I repeat the chrono test a couple of more times and the numbers come out similarly, I know it is close enough.