S&W M&Pc barrel lockup question


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the naked prophet
December 1, 2007, 09:29 AM
On my wife's S&W M&Pc .40 it seems like the recoil spring may be a bit weak. If I pull back the slide, and slowly ease it forward, it'll "hitch" right before the barrel moves upward to lock up. The slide will sit right there, and the spring pressure isn't enough to push the slide forward into battery. In every other auto we have (including 1911, BHP, Glock, Beretta, Kel-Tec, etc) the spring alone is enough to push the slide into battery even when the slide is resting just before lockup. It seems that the M&P relies on the momentum of the slide to continue pushing the slide forward into battery.

Her M&P has experienced failures to fire due to being out of battery. She's also experienced premature slide lock due to the slide lock engaging during firing, usually toward the end of the magazine.

Could these issues be related? Maybe a stronger recoil spring would push the slide into battery more reliably, and reduce the slide velocity when it impacts the frame which is what I suspect is causing the slide stop to "bounce" up and engage?

I guess what I'm asking is do any of you with the .40 M&P compact have the same issue with not going into battery under spring pressure alone? I'd appreciate if you could check and get back to me. If your M&Ps will lock up just by spring pressure (as opposed to momentum), then I may have to call S&W and get a new recoil spring.

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the naked prophet
December 2, 2007, 10:32 PM
Nobody?

kd7nqb
December 3, 2007, 04:32 AM
I just tried what you described with my full size M&P, seem like mine does not have the same issue. Dont know what to say.

FieroCDSP
December 3, 2007, 06:36 AM
Does it hang-up without ammo in it? If so, I'd send it in for service. If not, your ammo might be a bit on the long side, and/or HP's or Flat points can sometimes resist going in until the gun breaks in (500 rounds or so).

Regardless, the slide-lock on last round issue is related to the magazine follower, if I remember correctly. Smith was changing those out under warranty, though if you call them and ask, ad they confirm that's what it was, maybe they'd just send the followers.

Try some round-nose rounds for a while, and if it's still not going into battery, make a nice detailed list of all of your grievences, print it up, and call Smith for a send-in. Send the list with the gun.

the naked prophet
December 3, 2007, 10:35 AM
The slide does that with or without ammo. After a few hundred rounds, it'll hang up there every once in a while during firing, close enough to in battery to drop the striker, but far enough out of battery that the "out of battery" safety stops the firing pin and it only leaves a miniscule mark on the primer.

I'll call S&W and ask about the mag followers.

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