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Scoring of M&P Barrel.


Duluth
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It looks like a minor disruption in the shape due to the vents having been cut into the barrel.  It wasn't reground after the cuts were made MAYBE.  Or the grinding was only very close to the original barrel diameter.

If it were pierced the metal would be pushed very slightly away from the hole and the very slight enlargement in diameter would carry the arc of the cut, which it appears it does in both sides.

I'm not claiming I know how it was made, just that this method would account for the very slight displacement of the material around the cuts.

I have no idea if plasma cutting produces a similar disruption in material.

Possibly the tipping of the barrel during recoil would affect the top surface only and not the bottom in the same way.

 

Just a guess!

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58 minutes ago, janice6 said:

It looks like a minor disruption in the shape due to the vents having been cut into the barrel.  It wasn't reground after the cuts were made MAYBE.  Or the grinding was only very close to the original barrel diameter.

If it were pierced the metal would be pushed very slightly away from the hole and the very slight enlargement in diameter would carry the arc of the cut, which it appears it does in both sides.

I'm not claiming I know how it was made, just that this method would account for the very slight displacement of the material around the cuts.

I have no idea if plasma cutting produces a similar disruption in material.

Possibly the tipping of the barrel during recoil would affect the top surface only and not the bottom in the same way.

 

Just a guess!

I think Mag-Na-Port are the only ones if heard of that use the plasma cutting. Most others are machined and sized.

 

the inside of the slide may also have an imperfection or excessive tool mark, since it had to be cut as well.

 

.

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2 hours ago, Dric902 said:

I think Mag-Na-Port are the only ones if heard of that use the plasma cutting. Most others are machined and sized.

 

the inside of the slide may also have an imperfection or excessive tool mark, since it had to be cut as well.

 

.

But the wear marks have a short arc that mimics the vents, and they are in both directions from the center line of the barrel.  Cutting produced material compression to the edges due to the cutter edge "pushing" into the material, that compression extends out into the surrounding material.

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1 minute ago, janice6 said:

But the wear marks have a short arc that mimics the vents, and they are in both directions from the center line of the barrel.  Cutting produced material compression to the edges due to the cutter edge.

True

something is out of spec.

 

send the pics to S&W customer service and then they will call you with a consult and likely a shipping label for service.

.

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They responded with this...

 

 

"We would like to thank you for your e-mail and contacting Smith & Wesson / Thompson Center.

I have reviewed your photos and this is normal and not a cause for concern. As the pistol cycles, there will be metal to metal contact in this area.              

Thank You for choosing Smith & Wesson / Thompson Center products. Have a great day.

 

Smith&Wesson values its customers and we are happy to have served you today. Please do not hesitate to contact us should you require further assistance.

Regards, Steve"

 

I just sent them that photo for comparison  . Those are my Glock barrels with at least 1,000 rounds through each. The M&P barrel just seems to be badly worn after 500 rounds through it.

 

 

barrels.jpg

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10 minutes ago, Duluth said:

The inside of the slide area looks totally fine. No damage or scoring at all. Still looks like new.

Have you looked in the barrel for any disfigurement of the rifling or even slight bulges in the same areas?

is the accuracy changing?

is the recoil with the same loads changing?

 

.

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4 minutes ago, Dric902 said:

Have you looked in the barrel for any disfigurement of the rifling or even slight bulges in the same areas?

is the accuracy changing?

is the recoil with the same loads changing?

 

.

I don't see any damage to the rifling. There doesn't seem to be any bulging either. 

As far as accuracy, I'm not sure. It's new a new gun to me. I'm getting used to it. So far I'm the most accurate with my G42.

About 250 rounds into it, it did jam. Not a failure do feed or eject. I was able to clear it. I wonder if that's when the barrel scored. 

I haven't noticed any change in recoil, but I didn't notice the scoring in the barrel until I took it apart to clean it after a range session.

BTW...thank you all for your help. I appreciate it. 

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37 minutes ago, Duluth said:

I don't see any damage to the rifling. There doesn't seem to be any bulging either. 

As far as accuracy, I'm not sure. It's new a new gun to me. I'm getting used to it. So far I'm the most accurate with my G42.

About 250 rounds into it, it did jam. Not a failure do feed or eject. I was able to clear it. I wonder if that's when the barrel scored. 

I haven't noticed any change in recoil, but I didn't notice the scoring in the barrel until I took it apart to clean it after a range session.

BTW...thank you all for your help. I appreciate it. 

Are you a member of the S&W forum? Every gunsmith is there by department.

they would know in a heartbeat if it was something

if Eric doesn’t mind just this time, it’s here

http://smith-wessonforum.com/forum.php

 

.

 

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