breech face "dents"?

[BillR1]

After I got back from the range today and did my cleaning, I noticed some strange marks on my 9mm 5" Pro. They're "dents" on the breech face that line up with the two protrusions on the top rear of the barrel hood. I can feel a very slight "catch" when I slide the barrel hood upwards against the breech face into the lock position. It looks like the barrel hood has been slamming against the breech face slightly lower than the lock position.
I am using an APEX kit with light 9mm loads.
Here is a pic...

The gun has less than 1K rounds through it.
Any ideas?

 

[jaykellogg]

The chamber may be cut too deep or the ammo cases you are using may be on the short side. 1) are you using reloads? if so what is the case length? 2) What does the dimple in the primer look like?

I field stripped my M&P9 and a loaded round sticks out of the chamber just a tiny bit farther than the lugs, but several empty cases would go in farther than the the lugs. This leads me to believe that the bullet engages the lands of the rifling before the case mouth engages the end of the chamber.

My M&P9 does not have the marks you showed, I probably have 150 rounds through it.

 

[BillR1]

I am using light reloads, and the cases are fairly new.
I had a couple of light primer strikes that didn't fire during a match on Sunday, so I shortened the load from 1.140" to 1.120" and tried several different recoil springs to see if the spring was an issue. The gun was actually flawless yesterday. The primer hits from yesterday all look great. There were a few primers from Sunday that looked a little strange, almost like the primer wasn't against the breech face when it ignited. It flowed backwards into the teardrop on a few. It reminded me of the "Glock mark" I used to see when I shot those.

 

[jaykellogg]

I guess, based on my gun, I would strip the weapon and set your loads so a straight edge across the base of the load shows a bit of daylight at the barrel lugs. I only shoot FMJ, so you may have to experiment a bit with your loads especially if you are using cast bullets. It appears (to me) that the load should cushion the slide as it slams foreward.

 

[BillR1]

I shoot plated bullets; no bare lead.
Anyway, S&W wants to see it. The tech I sent the pics to said the barrel hood may need to be trimmed. They're sending me a shipping label. Now I have to get it back to stock to send it in. (sights, trigger parts, etc.)

 

[jaykellogg]

If it were me, i would ask before I did that. I sent in a Model 27 years ago that was spitting lead and they replaced the trigger spring to bring it back to 3#. (I had it at 2#). Regarding the sights, that won't have to come off unless they replace the slide.

 

[rrockefe]

If you are specific on what you want them to fix and what you want them to not touch, they will do as you request. You must include a letter in the package with the gun detailing your problem and instructions. I had the same concern when my slide lock lever broke and they insisted it had to come back for factory only replacement. I described my concern regarding a custom trigger job I had done and the CS rep. gave me the above assurance and instructions and they followed through on it perfectly. I think the concern regarding them "restoring to original" is sort of an "old wives tale". Perhaps it has occurred somewhere in the past with a safety issue of some kind.

 

[OKFC05]

Any ideas?

The barrel is not fit correctly, and it is easy for S&W to fix.
And no, the ammunition has absolutely nothing to do with your problem, and the ammo does not "cushion" the closing.

I agree with the advice to be very specific about the problem, and what mods you want left in the gun. One of our shooters sent in a Sigma last year (there was really nothing wrong with it) with a vague request to "update" the gun he bought used. They updated it all right: the entire sear block assembly was replaced, and all the polished sear block trigger pull smoothing was lost.

 

[BillR1]

The barrel is not fit correctly, and it is easy for S&W to fix.
And no, the ammunition has absolutely nothing to do with your problem, and the ammo does not "cushion" the closing.

I agree with the advice to be very specific about the problem, and what mods you want left in the gun. One of our shooters sent in a Sigma last year (there was really nothing wrong with it) with a vague request to "update" the gun he bought used. They updated it all right: the entire sear block assembly was replaced, and all the polished sear block trigger pull smoothing was lost.

I took the trigger parts and sights off because I'm hoping they replace the slide. I got the FexEx label today, so I'll get it sent off.

 

[BillR1]

Just spoke with S&W service department. The gun will ship out today on it's way home. They replaced the barrel and slide, and test fired it for accuracy. It should be here Tuesday!

 

[ArLEOret]

Good luck and let us know how Smith did on your weapon. Good turn around on your repair!

 

[BillR1]

The gun back arrived today with a new slide and barrel! (They didn't send me any new mags though...)
I'll shoot it tomorrow and see how it does.