Trouble with oversized barsto barrel install on M&P

[mumzer]

I recently purchased and had professionally one of Barsto's new match barrels installed in my M&P. The smith is a capable and well trained (E8 or E9 Ordnance soldier) with proper machines. I have had great work from him on 1911's in the past and figured this would be a walk in the park.

The barrel was substantially over-sized (hood length and width) and required material removal to drop into the slide. The lower lug also had extra material that required removal. The work was done quickly and the lock up feels massively improved. Pistol head-spaced fine and passes all plunk test criteria. Pistol passed a function test into a sandtrap at the gunsmith.

On the first outing to the range using a variety of 115gr factory ball loads the pistol will occasionally ftrtb. It will strip a round properly and appear to go into battery, but stops just shy. The typical love tap on the back of the slide does nothing - slide will lock up tight. I can clear the stoppage with a forceful rack or by a 1 handed clearing technique on my holster and continue firing. Every mag or so i get a repeat stoppage. Accuracy is terrific. I come to the M&P from 2011's. I have occasionally run into a 1911 extractor with too much tension or shitty contours that would stop the case lip from sliding up the breech face, but it always happens much earlier in the chambering cycle.

Brass looks fine - no signs of overpressure. There are no apparent chamber flaws. breech face and ramp look ok (although i have to say there is a major tool mark in the underside of the top of the breech hood). There doesn't appear to be any vertical fretting on the barrel or breech face or evidence of the extractor fretting on the barrel.

The smith is suggesting i run more round through to break it in (which might make sense if taxpayers payed for my ammo and sidearm) and barsto is closed for the holidays.

I'd be interested to hear any suggestions or additional things to look for.

thanks

[Service Desk]

Sounds like it is fitted real snug, I would check the chamber against the loads. I have a Barsto 9mm PO barrel that has a super tight chamber. Any bullet bulge at all and i have the same lockup issue.

I am going to ream the chamber with a new Clymer reamer when I feel the urge.

[mike cyrwus]

probably needs some ramp work. specifically the top edge. When you turn a file cabinet into a bank vault, youre bound to be jiggling some handles getting it open.