M&P 40 barrel bulge at muzzle??

[saskgunowner101]

Seeing I'm still kinda new to pistol shooting,I was wondering...on the M&P,why does the barrel diameter change near the muzzle???I have nothing to reference it with,just seems strange that the last half inch is slightly thicker o.d.Thats where barrel wear is showing up too.It seems there's a few members here with this pistol,so what gives??Are they all like this,and if so,for what purpose??

 

[Trigun]

Barrel finsih wear due to the action cycling is normal but bulge seems not quite normal to me, any pics?

Trigun

 

[.88 magnum]

Probably to match the dia of the bore in the slide. Keeping it tight, or no play.

 

[ian_in_vic]

Yup, that's the first point of lock up, the second is at the locking block, and the third is at the e-port. This allows the the barrel to be perfectly locked to the slide when the pistol is fired, providing the alignment of the sights to the bore. Not only normal, this is critical. The only other way to accomplish the same thing is with a seperate barrel bushing at the muzzle, like the early Colt-Brownings (1911 etc.).

 

[saskgunowner101]

Glad to know its normal!When I'm cleaning,I worry about the insides mostly,and just give the barrel a quick wipe on the outside.Guess I'm guilty of paying attention now.So,about these markings on the ejected brass...