I'm still kinda new to guns, but, my question is at the bottom.

So, I took my m&p 10 out of the back of the closet to give it a look over to make sure its still clean and oiled before I get an opportunity to take it out next. I've owned it less than a year and only have maybe 300 rounds through it, as I don't currently live near any ranges or own any land. Since I had it disassembled I was giving the inside of the barrel a good look and noticed something that looked raised.. I tried running patches through it and using brushes, it's still there. At this point I'm wondering if I've ruined the barrel by not cleaning or oiling it well enough and it has subsurface rust. Finally as I'm flipping it over and taking the flash hider off to get a better look, I see the barrel stamp that reads "308 WIN 1/10 5R", which as it turns out happens to line up with these spots a little too well for me to think its coincidence..

I was hoping someone could let me know if what I'm seeing is actually the inside of the barrel warped by the barrel stamping or not, and if so how badly does that affect accuracy?

Barrel is upside down in second 2 images.

Attached Images

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It's certainly not right, but it is near the chamber so I wouldn't worry about it.
Because the bullet still has a chance to obturate to fill the grooves before exiting the muzzle.
If it shoots a good group, I wouldn't worry about it.
I wouldn't LIKE it, though.

It's actually about 2-3 inches from the muzzle, not the chamber. The first image in the picture I attached is the barrel with stock flash hider removed. As for how it shoots I can't really say, because I haven't gotten a chance to put it in a bench rest, but I kind of want to now knowing about the denting.

Seems like the original question isn't getting much traction. Can anyone with an m&p 10 check the inside of their barrel to see if they have the same denting where the barrel stamping is?

I've got an old US military bolt gun with a barrel that looks like 26 inches of bad road. Shoots 1 MOA. I had a .222 that shot one ragged hole. After I pulled the barrel and sectioned it, I couldn't believe how bad the pits I'd seen were.

You might try JB bore paste to clean things up and look again. It doesn't look like distortion to me but some surface condition. I read some posts about distorted bores in that area, but those rifles wouldn't group.

Stamping marks is exactly what it looks like. You'll not polish those marks out. You have the thin barrel and the stamping is deep, which caused this problem.
My MP10 has the unthreaded standard heavy diameter barrel and does not suffer this problem.
S&W needs to know about this problem and see your pictures, I'm sure they'll want the rifle sent in to replace the bad barrel.
I bought the S&W MP10 because they Nitrocarburize (nitride) the barrels which makes a superior metal treatment. I would not replace it with an aftermarket barrel.
Who would have thought??

My bad. Wasn't thinking .
Yeah. Send it back.

Someone else here had the same problem. S&W replaced it

Yup, jus looked at mine and I have the same issue. Does anyone here know if S&W gets upset when you send back a rifle with a few upgrades?
chris

Word has it they void your warranty if any upgrades are done to the rifle. I think there was some sort of announcement or release from S&W a couple years back on that. You might want to check out their web site about the warranty and maybe give them a call to be sure.

That's too bad. Ruger removes the non stock parts, replaces them with factory, sends your aftermarket stuff back with the now fixed firearm, and bills you for the new replaced parts, minus whatever was defective that they had to fix.

There seems to have been a few barrels this way. Call them and send it back! I don'n think they ask too many questions about this issue from what has been said.

NCchris,

You might want to see a thread I posted here not long ago. Only a little bit pertains to your question of the warranty being intact after modifications, but I think I have the answer for you here:

Hope for future spare parts?

NCchris,

Not sure if my post is being moderated or if it was not allowed due to a link being in there (if it's just being modded, please delete this post after it's blessed off on). I posted about future spare parts for the M&P10 here in the M&P10 forum within the last 60 days and, while only a small portion of that post addresses your question about being in warranty after modifications, I believe this is a pretty good answer...straight from the horses mouth. You might want to check it out.

Thanks for this info and your post. S&W has my MP-10, we'll see how it goes. I couldn't put the original gas block back on because of the handguard upgrade and because I "dimpled" the barrel for the setscrews in the low profile gas block. This is no way related to my issue. I'll keep you all updated. I am optimist!
Chris

They replaced the barrel! No questions asked! They even re-installed my low profile gas block and Troy hand guard.
Chris

I'm really curious why they would stamp the barrel that way. Why not laser etch? No metal deformation.

I have a high end Ruger 10/22 barrel that was laser etched with the info and ser# so the dimensions weren't compromised. Actually was very reasonably priced, and came from a small shop. If HE could do it, no reason S&W can't.

NCChris; Great outcome! Now shoot for group at 100 yds and tell us the results.

Mine looks like glass. Rifled glass. Guess I got lucky.

great outcome.
i've now checked mine, and glad to say it does not have this issue.