KKM Barrel and M&P Pro

[insertgenericid]

Hello all,

Long time lurker here. I've benefited greatly from all the advice I've observed over time.

I just picked up a second M&P Pro 5" in trade, as well as a KKM barrel. This is my second Pro, my first being my favorite pistol to shoot despite some subpar accuracy and a dislike for 115 gr bullets.

I attempted to install the KKM in the new Pro, and found while cycling the action that it feels like it "hangs" just a split second when drawing the slide back. Further, if I ride the slide into battery at all, the slide stops a fraction of a inch from all the way forward. I can push it the rest of the way with my thumb, and it the barrel appears to have locked up, that is the barrel doesn't visibly move at all in that last fraction. I can still dry fire the gun, but I'm now worried that it would be unsafe to fire.

The KKM barrel fits without issue into the old Pro, but the trigger on the new one is, out of the box, nicer than the old, which has a quite a few rounds through it. I'd like to keep the KKM barrel in the new, but am I running any kind of risk?

Thanks all!

[wgj3]

Shouldn't be a problem, but you could try swapping slides to see if that helped. Old slide that seems to fit new barrel better on new frame with trigger you prefer. The KKM should fit snugly and would most likely "break-in" after a few hundred rounds in the new pistol. Hand cycling is not much like the way the action works under normal circumstances when fired.

Edited July 29, 2013 by wgj3

[partyboy424]

KKM says they don't need to break in. I've got two of them, they definitely do need a couple hundred rounds.

[chuck s]

Mine took a few hundred rounds to really slick up, but I never had any real problems with it prior to that. The accuracy on mine was no different than the original barrel until I replaced the locking block ( for some reason it had longer slide rails than the original) then it became a different gun, with as good accuracy as I could hope for in a plastic gun.

[S391]

Mine took a few hundred rounds to really slick up, but I never had any real problems with it prior to that. The accuracy on mine was no different than the original barrel until I replaced the locking block ( for some reason it had longer slide rails than the original) then it became a different gun, with as good accuracy as I could hope for in a plastic gun.

What is the locking block and how do you replace it?

[Forrest Halley]

The locking block us the metal piece that sits in the frame atop the trigger. It is the piece the forward slide rails are integral to. It is removed by pushing out the roll pin and pushing and twisting out the disassembly lever. You may need something to help get it out of the frame. I used two Allen wrenches as simultaneous levers under the slide rails. Worked like a charm.

[cyberiad]

I am not a gunsmith but the KKM barrel I had to (slightly) fit to my G34 does exactly the same thing and, based on what I have read, the condition will increase "dwell time" and thus, potentially, accuracy. I have fired about 700 rounds through my barrel and it still "hangs" slightly if I cycle the slide slowly by hand. It's so accurate, particularly with properly sized lead bullets, that it never occurred to me that it might be unsafe; as far as I can tell it never happens in live fire.

[insertgenericid]

Thanks all for the responses.

[coordinator]

Who supplies replacement blocks?

Have any of you experimented with a replacement block and stock barrel?

[chuck s]

Speed shooters specialties.

My gun did not improve with the new block and the original barrel, only when I tried the kkm and the new block did thing improve greatly. The strange thing to me ,is that that the new block was not the same as the original, the rails were longer. I ordered another one for a spare, but its rails were the same size as my original block. My gun now shoots groups as small as my glock 34 and not too far from my Stock11 tangfolio.

I also have one of the new tighter twist barrels and it is better than the original barrel, but no better than the kkm

[insertgenericid]

Update for everyone, I put the barrel in the newer Pro and ran some rounds through it. No problems functioning, and a clear increase in accuracy.

[coordinator]

Thanks for the update and additional posting. I'm going to change out the barrel and block in mine too. The only draw back is I've been using that to excuse to explain away my c and d hits......... What will I tell them now? Yeah it's the sights.

Regards