I have a Mega forged lower with a RRA LPK installed. It has never had any issues with any mag until it met two gen3, 20rd Pmags. When the bolt is closed, the gen3 Pmags are a real bitch to seat. It seems like the top dust cover tabs are larger than the gen2s. The tabs seem to bind somewhere toward the top of the magwell in the last millimeter of insertion. It doesn't matter what upper I throw on either. If I insert the mags as perfectly straight and centered as I can, they seem to click into place with no problems. If it's a careless slap in, they will bind and not engage the mag catch and then fall out.

Like I said, the two gen3 Pmags I have are both 20 rounders; so, I don't know if 30 rounder gen3s act the same way. One mag seems to bind worse than the other, but they both bind. I can tell you if the bolt is open and I load either, there are no issues and everything cycles just fine. If they are loaded and the bolt is closed, the binding starts, but they bind bolt closed, unloaded too -- just not as much.

I'm either going to stick with my existing gen2 Pmags or change to Lancers. I bought one 20rd and one 30rd Lancer L5 AWF mag. No issues with either no matter how full or empty they are or if the bolt is closed or open. Gen2 Pmags are the same way -- no issues. I'll just have to decide which way to go for future mags. If a buddy has a gen3 30 rounder I can test, I'll try it out and report back, but I don't want to dump any more money into gen3 Pmags if they are all going to bind with this particular lower.

Holy shit! That's it! Thanks for the link.

I have to say, my faith in Pmags has been shaken a bit.

The date codes on both of my gen3s are 6/13 with a 05 in a recessed circle above the date.

My 40 round gen 3's are tight with 40 rounds,I just download by one ....no problems at all with my 20 and 30 rounders

Not sure when you got your mags but there were issues with the 20s for while that magpul as since addressed and will swap them out for you,

http://www.ar15.com/forums/t_2_124/235389_Gen_M3_20_round_magpul_issues.html

my  gen 3 30  rounders are the same way I just figured it was the new design so I just load them with an open bolt

I heard back from Magpul. They want to swap my gen3s out for gen2s at no charge.

Magpul is swapping out Gen 3's for Gen 2's ??????? Tell me this was a typo

Only for this particular forged lower. Pmag M3s work fine on forged (and most other) lowers