Home Forums Hunting & Shooting Handguns Testing Pistol Ammo Loaded With Small Rifle Primers vs Small Pistol Primers

Trudat.

As promised, I went out and ran my own test today to add to the knowledge base. The test guns were a Sig P365 and a Sig P365 XL. I used 124 grain Precision Delta jacketed round nose bullets, 4.3 grains of W231 and mixed brass, loaded to 1.155" OAL. All results were obtained using a Labradar.

The primers were recently purchased Federal No. 100 Small Pistol Primers and some older Federal No. 200 Small Rifle Primers in the old red box. (If I use any rifle primers in my pistols, these would be the ones, so I used those. Sorry.) The results were:

Sig P365
Federal Small Pistol- Average 1017, high 1028, low 1005, extreme spread (ES) 23, SD 7.6. 10 shots
Federal Small Rifle-Average 1020, high 1035, low 1002, ES 33, SD 9.7. 10 shots

Sig P365 XL
Federal Small Pistol-Average 1059, high 1076, low 1042, ES 34, SD 11.0. 10 shots
Federal Small Rifle- Average 1057, high 1084, low 1044, ES 39, SD 12.2. 10 shots
(Also, from notes, using Winchester Small Pistol Primers for Standard Loads-Average 1043, high 1060, low1025, ES 35, SD 13.9. 5 shots.)

There were no malfunctions. I did not test for accuracy, but the velocities are the same and I would not anticipate any difference. I should have compared the primers in the fired cases like Waders did, but I forgot. I will have to do that next time I load using SRPs.

Take care!

Cheyenne,

That's good stuff--no real difference between the two!

OK, I have been Googling around the Internet for opinions on doing the swap. Some have suggested that there can be breach face erosion if you use rifle primers on lower end loads because there will not be a good seal between the primer and the primer pocket. One guy claiming to be some kind of master reloading instructor guru suggests that equal velocities do not mean equal internal pressures, and that some primer/powder combos can cause an early high pressure spike that would still result in the same velocity as some primer/powder combos that do not spike as high. So, it may or may not be enough to just chronograph the same loads/guns with the only variable being a primer swap. Everyone should take a look for themselves and figure out who they want to believe and how much of a risk they are willing to take.

Sorry to be a pain, but I edited the post directly above this post two times. If you previously saw the post before the final edit, and you only look at new posts when you log in, please take a look at the above post. I know we have some technical experts here, and any comments or insight would be most appreciated. Thanks.

I've shot thousands of 9mm with SR primers and no leaks. Mostly CCI400 and older WSRP. I had a bunch left over after I stopped shooting HPR. My Tupperware guns and 1911's set them off just fine. I do not use reduced loads for 9mm, that may contribute to my success?

Statistically, no difference. Very good to know.

Thank you for taking the time to perform the tests and provide your detailed field report.

But is it claimed potentially possible pressure abnormality likely in this situation?

I doubt it.

The person had no data to support his claim on this particular point. He was talking theory and took the position that it was best to not take a chance. That was on SigTalk.

I was hoping that you would weigh in on this point.

Excellent follow up Cheyenne. Thanks for posting.

John Linbaugh told me years ago that in testing load data in pressure barrels for the 475L that rifle primers could increase pressure as much as 10,000 PSI without a corresponding increase in velocity

10K PSI and no change in velocity?

Not sure I buy that. I'd like to see the data and which variable correlate with the difference.
Were these alleged difference with using Magnum Rifle Primer?

No "corresponding" increase, I didn't say none and I didn't how much increase. I posted just like I was told. He said "rifle primers" and I didn't ask about magnum VS standard

jwp475, based on your experience, do you have an opinion as to whether the substitution of a small rifle primer (non-magnum) for a small pistol primer in a standard pressure 9mm would make a significant difference in pressure? I would appreciate any insight that you could provide.

Thanks!

I have no experience with this and only related what I was told by a man that had pressure tested them in the big revolver cartridges

Ok, thanks for responding.

The physics can not lie. If there is no change in velocity then there is no change in pressure. The pressure curve may change, but when only one variable is changed and results are the same, that implies the rest of the experiment remains the same.

That is not exactly true, as John Linebaugh's pressure tests proved in the Linbaugh revolver cartridges pressure increased with large rifle primers without a corresponding increase in velocity
The theory was that the rifle primer was over lighting to powder effectively increasing the burn rate
How this relates to 9mm and small rifle primers i have no idea

I've never tried that, but 40+ years ago I had a Ruger 77 in .308 Win that would not reliably fire my reloads with Large Rifle Primers. The firing pin would not dent the primer enough to ignite the primer. So I substituted Large Pistol Primers and problem solved.

Managed to get out today and add some data to the thread using a S&W M15 .38 Spl and a Ruger GP100 .357. Only tested three loads side by side with SP and SR primers but these are my go to loads for these guns so figured if this works I can use up a stash of CCI-400's that I don't want to use in my .223.

All results are 5 shots at 10' instrumental using an Oehler 35. Air temp was 35 deg.

S&W Model 15-6, 6" barrel
Winchester brass, my cast 158 grain WFN powder coated bullet (Accurate mold 358160) 5.5 gr. of True Blue
............CCI-500..........CCI-400
High............904................920
Low.............889................898
ES................15..................22
Avg..............896................909


Ruger GP-100 6" barrel
R-P brass, same 158 WFN cast and powder coated, 7.0 gr. True Blue
............CCI-500..........CCI-400
High..........1091..............1096
Low...........1049..............1030
ES...............42..................66
Avg...........1068..............1078

R-P brass, LBT 160 WFNGC, 16.0 gr. 296
............CCI-550..........CCI-400 - Note the small pistol magnum primer here, that's what would normally be used with 296 powder
High..........1318..............1348
Low...........1265..............1216
ES...............53.................132 (yowza!)
Avg...........1301..............1284

Groups for each load were not significantly different between the primers in all three examples and are about what might be expected firing two groups of the same load side by side. In fact this last load with 16.0 296 and a huge ES produced the tightest group of the day and the .38 load with CCI-400's was the next tightest. I have no way to measure pressure but brass extracted normally and obviously velocities stayed pretty close.

Basically this shows the same as Waders and Cheyenne - there really isn't any significant difference between using Small Pistol and Small Rifle primers although it does appear that the SR do provide a slight increase in velocity.


A final comment on the last load using 16.0 296 and CCI-400. The individual velocities in the string are 1216, 1292, 1288, 1348 and 1280. It looks like it wants to cluster around 1280-1290 fps with one very low and one very high reading, that skewed the ES badly and lowered the average so it was less than with the Small Pistol magnum primers. Or maybe that difference is true due to the SPM being hotter than standard SR primers. Don't have any ideas on that, as noted it produced the tightest group of the day at 25 yards. I might have to repeat that comparison with a couple of 10 shot strings.