Range Report – Standard Small Rifle Primers vs Magnum Small Rifle Prim

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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.

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