Range Report – Standard Small Rifle Primers vs Magnum Small Rifle Primers, in 223

I was wondering about the difference in velocities of reloads using Standard Small Rifle Primers as compared to reloads using Magnum Small Rifle Primers. I know for a fact, that Magnum Large PISTOL primers produce higher velocities than Standard Large Pistol primer. I experienced it while shooting rubber bullets (no powder) from a 44 Mag case with only a primers, no powder. I wondered if the same was true of small RIFLE primers.

I used Federal Standard Small Rifle Primers and CCI Magnum Small Rifle Primers. I wished I could have used Standard and Magnum primers of the same brand, but didn’t have one brand of both kinds of Small Rifle Primers.

I shot them from my Olympic Arms AR15 with its 16 inch barrel.
All reloads contained 20.0gr (trickled for exactness) of H4198 powder.
All reloads contained 55gr SPBT bullets purchased from Berry’s.
I used a Chrony F1 Master Chronograph to get their velocities.
Sky Screens 15-20 feet from muzzle. So, muzzle blast shouldn’t have been a factor.

My hypothesis was that Magnum Small Rifle Primers (MSRP) would produce higher velocities than Standard Small Rifle primers (SSRP) – same as Large Pistol primers.

My hypothesis was not supported by my experiment. I found that:
the velocity of a bullet fired with a SSRB was, on the average, 2767.
the velocity of a bullet fired with a MSRB was, on the average, 2722.

My conclusion is that MSRP, with their thicker cup, contains less primer accelerant (powder).

Here’s the data. Velocities are in chronological order (so I can more easily so the range), not the order produced when the string was fired. However, the 2 slam fires are where they happened.

Standard Small Rifle Primers

Stan Sm RI Prim
20.0 ! - H4198
3/21/2009

1 2677
2 2715
3 2738
4 2741
5 2763
6 2770
7 2773
8 2781
9 2781
10 2787
11 2804
12 Slam Fire
13 Slam Fire
14 2810
15 2828

2766.77
Average

Give or Take
61.23

Magnum Small Rifle Primers

Mag Sm RI Prim
20.0 ! - H4198
3/21/2009

1 2651
2 2675
3 2682
4 2684
5 2688
6 2694
7 2721
8 2734
9 2735
10 2737
11 2751
12 2756
13 2771
14 2776
15 2781

2722.40
Average

Give or Take
58.60


BTW - The thinner skinned SSRP produced two slam fires during their string of shots. The thicker MSRP had none. So, if using SSRP use good range safety – as you would do anyway. But, I often point the AR upward as I depress the lever to send the bolt forward, loading the first round of a new mag. I was on the porch of the cabin myself and my brothers built on our hunting property. I’m glad I didn’t have any slam fired then, or I’d shot a hole in the roof.

Hack

Thanks for the results
I am certain you are aware that testing across makers is more or less meaningless, as we all "know" federal primers have a higher Brissience (sp) than anyone elses.

quote:

Originally posted by jeffeosso:
Thanks for the results
I am certain you are aware that testing across makers is more or less meaningless, as we all "know" federal primers have a higher Brissience (sp) than anyone elses.

Yeah, I didn't like doing it, but with the supplies of primers these days, I couldn't get one brand of both kind of primers.

If I ever do, I'll run the experiment again.

Hack

quote:

Originally posted by jeffeosso:
Brissience

???????????

While it is true that comparing small apples to large oranges doesn't tell you much about large apples or small oranges, your test does demonstrate that the common assumption that "magnum" primers always create more velocity or pressure than "standard" primers is an inaccurate one. Thanks for posting, and if you have a chance to run some comparisons on the same-brand primers, please post that also.

Another consideration is powder. Some primers may simply act differently with different powders. AND case/bore size. No test is complete without comparing larger calibers and cases, also.

quote:

your test does demonstrate that the common assumption that "magnum" primers always create more velocity or pressure than "standard" primers is an inaccurate one.

without running such a fine test as done here.....I've reached this conclusion about large rifle primers and LR magnum primers as well

Pressure and velocity seems to be overwhelmingly controlled by powder type, amount, and bullet weight.....and to a far lesser extent the way the fire is lighted.

quote:

Originally posted by Duckear:

quote:

Originally posted by jeffeosso:
Brissience

???????????

I believe he means "brisance", the heat or energy of a primer.

Jim