Specifically Winchester Small Pistol Primers in .223 Rem mid range (24gr H335 - 55gr bullet) loads. I have heard generic warnings about pistol primers having a thinner shell but am trying to verify and see if anyone has experience with this?

Edit: This would be used in a modern bolt action rifle (Tikka T3 Varmint). Have not tried it yet, asking around first.

Aside from pressure considerations (shouldn't be that much of an issue with extremely light loads, I would think), I would be more concerned about slam fires in semi-autos with floating firing pins. Of course, extremely light loads won't cycle such guns anyway, right? But how about the act of dropping the BCG of an AR on a pre-chambered light load when single feeding it? Would the firing pin have enough inertia to detonate a thin SP primer? Dunno. Spitballing here.

In larger cartridges, in single shot rifles, I use LP primers in lieu of LR primers with zero side effects. Specifically .32-40 cast target loads comprised of 14 grains 4227. Possibly comparing apples to oranges here though.

This may not be a good comparison, but I use SP pistol primers exclusively in 22 hornet loads and have shot 1000s with great results.

Really no difference in their performance

I have had primer piercing problems in some 700s with sloppy firing pin holes even with normal small rifle primers like WSR and Fed 205/205M, I have had to switch to Remington 7-1/2s in one gun. When this bad thing does occur, it causes the pressure to vent through the bolt body then through the trigger assembly smashing the sear surfaces together hard enough to break the edges rendering the trigger inoperable .. pretty expensive requiring at least repair if not full replacement. So I'm going to recommend caution.

With small rifle primers starting to be available again, I would recommend getting correct primers rather than trying shortcuts. New triggers are pretty expensive.

I have heard, on pretty good authority, that CCI 550 Small Pistol Magnum primers are the same as "standard" CCI 400 Small Rifle primers, with the same thicker cup to withstand the pressures in some of today's magnum handgun cartridges.

I just shot some .223 using the CCI Small Pistol Magnum primers (CCI 550) in a reduced load. The load was 20.5 grains of IMR3031. I was sighting in a rifle at 50 yards and didn't need much velocity. There were no signs of pressure.

kwg

I have used small pistol in 22 Hornet, 218bee, and 222 with no ill effect. All in bolt guns.

I do have a couple hundred small pistol mag primers. May try those first.

20-something years ago I got a pierced small pistol primer with a 22 Hornet load. I was only using them after reading about how you don't really need a powerful primer to ignite the small volume of powder in a Hornet case. Along with how the powder ignition may be more uniform with the pistol primer. Had shot quite a few with those primers and that one round was the only problem. Wasn't a hot load and I never noticed much difference when using them, so I went back to regular small rifle primers.

Shooting Sage Rats, I use pistol powders and shot gun powders...have shot well over 50,000 rounds using Small pistol primers in them... usually prefer the Magnum ones...but under Obama you got what you could get...

now under Biden, I'm back doing the same to preserve my stock of small rifle primers... I don't shoot a lot of pistol..

I do wear safety glasses, and have had the occasional pierced primer.. but considering the number of rounds I've shot, that ratio is mega low...

These loads have been fairly accurate out to 250 yds on a regular basis...

This has been in bolt actions, not ARs. However I have been aware of folks using these loads in ARs, where they have changed the spring to the one out of an AR 9. Never witnessed it first hand tho...so I'm passing on other folks info.. so take that with ever how many grains of salt you desire...