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All suspect CCI SPPM 9mm loads were <130pf, many ~125pf. Almost all 9mm brass was once fired (i.e. reloaded for the first time). I have >30k of 9mm brass and a system to cycle it. Regardless, I can't see 125-130pf 9mm loads wearing out brass after one loading. And, the .45acp small primer brass was once fired for sure. Can't get much better than that for non-new reloading brass. I'm sticking to my belief of too low pressure not deforming the harder CCI SPPM primer enough to seal the pocket. The data supports that. I changed nothing in my test of SPPM other than increasing to >140pf and the gas cutting stopped. And, I think the SPPM gas cutting in the much lower pressure .45acp lends added support to my too low pressure theory. YMMV, but I have my answer. p.s. As a reminder, my 30k of CCI SPPM were the older red box variety. New CCI SPPM, and other brand SPPM, may vary.

I burned 8# of TG in 9mm lead. It worked, but I found it to be nothing special at day's end. And, I'm not running LRN in 9mm for now.

As noted, my experience relates only to ~20k of CCI SPPM w/ Unique and Titegroup in 9mm using mixed brass and >1k w/ Bullseye w/ .45acp using Blazer small primer brass. As noted, powder burn rate did not matter. My opinion based on my experience is that it's due to too low pressure (>130pf, and well under at that) in 9mm and too low pressure in .45acp regardless. I only run SPP now, but would likely be fine runnning SPPM >140fp in 9mm if that's all I had. p.s. I will not run .45acp in SPPM again because I don't think the pressure can safely get high enough to cause primer flow that will reliably seal the primer pocket.

Loads near and under 130pf w/ CCI SPPM resulted in gas cutting for me. And, as show in the photos, the low pressure rounds show very little if any primer flow. However, it's a bit easier to see primer flow in a Glock because of the large striker opening. The 4.7gr Unique noted above resulted in clear primer flow, but I'm running 4.9gr (~1150fps) for a bit added insurance with the last CCI SPPM I have. The question I have is whether the 147gr @ 925fps (~136pf) loads show enough primer flow. If not, it could be an issue. If so, he should be okay. But, I don't have experience with Rem or Fed SPPM. What's the velocity on those? If you are getting primer deformation pressure is likely high enough to deform the primer enough to completely seal the pocket. Loads I ran in high volume w/ CCI SPPM (that gas cut) were ~1000-1050fps w/ 124gr FMJ/Plated resulting in a 130pf or under. These were weak loads. My SPPM loads in this test were ~1150fps (>140pf) and have not show issues, but I can't run these in high volume with CCI SPPM to be certain because I traded my remaining 9k for SPP. CCI are harder. That's been my experience as well. These CCI SPPM are the only primers I've ever had repeated light primer strikes with in Glocks.

Not sure, but you should be okay as that is not a real weak load like I ran. Also, yours are Rem SPPM and mine were CCI. I can tell you the loads that gas cut for me where using older red box CCI SPPM running under 130pf, many well under. As noted above, primer flow (i.e. deformation that will seal the primer pocket) exists running about 140pf, and I'm running everything at least that now with the last bit of CCI SPPM I have. I can't speak from experience for loads around 135pf w/ CCI SPPM because I did not run them in the test process noted here.

Bullseye. I keep it old school. Runs very well for me.

If you are running 1k or more a month in 9mm consider the Dillon 550 or SDB. I run a dedicated pair of Square Deals in 9mm and .45acp. I believe the SDB to be the best value in mid-volume handgun loading. I run about 1k in 9mm and about 250 in .45acp monthly. I'm pleased with the press and Dillon's customer service is amazing.

I settled on 1.135" w/ 124gr FMJ.

I have run SPP, SPPM, SRP and SRPM in 9mm. And, in a variety of brands run interchangeably. Overall, not much changed, but the SPP loads seemed most consistent.

I liked Solo 1000 because it was low smoke for lead. Not my first choice for much else. I've moved on.

This. And, OAL does matter. If memory serves, TG @ 3.7gr @ 1.135" would barely cycle my Glock 26, though I could get 3.4gr to dribble out of a Glock 17. I go with 4.0-4.1gr.

I can confirm the above when used in weak 9mm loads, as well as SPP .45acp, from experience (as linked above)

Final Update: I ran matching loads in CCI SPP and CCI SPPM. The SPPM are harder. My testing puts this to bed for me and conclusively proves that harder SPPM, SRP and SRPM can cause breech cutting around the primer cup using weak loads because the primer does not deform to seal the primer pocket. Picture of SPPM vs. SPP: These two cases are representative of loads fired. I've since traded all my SPPM for SPP. The SPP indent and primer flow is more pronounced, and it's much more noticeable in real life.

I've reloaded them changing nothing. Worked the same as LPP. I just keep collecting them for a day I have only SPP on hand. That's day has yet to come though.

Yes, the best. I have a handle on the way for my (>35k) 9mm SDB to replace the broken one, and the new style brass bushings to replace the older/worn plastic ones on my (~10k) .45acp SDB. Both my SDBs are original (i.e. old school), and all the parts that have broken over the years have been redesigned to be more robust.