16 inch carbine length 223 wylde ar that is over gassed. Runs but throws shells way forward. Mushroomed the tip of a carbine buffer.

Thinking it's beating itself up inside I stepped up to an H and the last couple trips it ran but I pulled out bent firing pin retainer pins when I got home, for the first time. Ejection pattern moved back a tad but not much. Ordered a Spikes St 2 that comes in a little bit over an H but below a standard H2 thinking excessive gas was just manifesting itself in other ways. But now I am wondering if the heavy buffer is causing the pin to hit the retainer too hard when the bolt goes home. Just curious if anybody has seen this.

Order is already in for the Spikes which specs say comes in between 4 and 4.3z. So I guess I'll do a couple hundred rounds with it and see what the retainer looks like and figure whether I should just go back to carbine buffers. Or maybe try to find something between standard carbine and H. But if full H didn't change the ejection pattern too much I'll probably just sell the Hs and put a good quality standard carbine back in.

And no the ejection pattern itself was not a worry, just don't want it to be chewing up parts.

Its not likely the buffer caused the firing pin retainer to break. The firing pin takes the most abuse from the hammer hitting it.
It does sound like your rifle is taking a beating from being way over gassed. I think that my first suggestion would be to try a adjustable gas block.

$12 + s/h to stop the fp retainer from bending.

KNS PERMA PIN FIRING PIN RETAINING PIN

IME it's from the gun being overgassed and the BCG hitting the end of it's travel hard enough for the firing pin to bow out the retaining pin. I think

I have a cut down 10.3 with a .072? I think? gas port - without a can on it, it runs/shoots great with an H2, just about perfectly gassed with M855. Brass poops out around 4:00 or so. No problems with the firing pin retainer.

With a can on it (admittedly a high blowback older can), it ejects around 1:30-2, but it bends the hell out of firing pin retainers. I wound up buying that KNS pin listed above, but my concern now is that I've stiffened that up, it might start bending that firing pin flange...we'll see I guess

It would probably act better with a clone correct RC2 on it, never mind newer revs of flow-through cans...sadly that's not really in the cards for it just yet

My PSA AR-45 is the only gun I've had that destroyed the buffer retainer.  It broke the tip completely off the little bastard.
Its not a huge deal, IMO.  The gun still runs fine without a buffer retainer, so long as the little piece that breaks off doesn't find its way down into the moving bits and jam something up.

disregard

On top of being over gassed, if the bolt tail or the inside of the bolt carrier where the bolt tail rides is out of spec allowing too much gas to blow by, this will cause bent firing pin retainers.  Had this happen with a cheap PSA BCG and a Toolcraft Nickel Boron BCG.  I only use Colt or Microbest BCG's now.

This has always been my drama queen upper. That one that feels cursed. Had to return to vendor for feed ramp work. Feed ramps were so bad I din't put together a long enough string of fire to see that the ejection was a weak dribble and required an extractor spring in the bcg I was running in it. After that optic shit the bed so had to put a new one on and take it back out. Now that it's feeding and shooting and ejecting and has a solid rds I put it to work a little bit and found it ejects forward and chewed a buffer tip and a couple firing pin retainers. I have had a sneaking suspicion when the vendor did the feed ramps they opened the gas up a bit to make sure it never comes back  to them again  but no way to prove it. Could have always been over gassed and I didn't see it until it was really up and running.

Probably step 1 will be a couple hundred rounds with the spikes 4 ounce buffer I already have coming. Pull the bolt out, look at the retainer.  Maybe depending on results another hundred with a different bcg from my bin. Break the bolt down again, Decide where to go from there.

No.