New MP Sport having problems...need ideas - Page 1

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[ARCHIVED THREAD] - New MP Sport having problems...need ideas

Posted: 1/12/2019 8:48:21 PM EDT

I’m trying to help a friend that took his MP Sport out for the first time. Each time he tried to chamber a round the bolt wouldn’t go fully into position/battery. It is so close to chambering...maybe 1/4 inch from going fully into battery.

I came and got it thinking it was something easy. Maybe a BCG problem. Swapped BCGs and it was still happening.

Thought it was an ammo/magazine problem so I tried a new mag and different ammo and it did the same thing.

Thought it was a lubrications problem. Lubed it and it was still doing it.

What am I not thinking of?

Posted: 1/12/2019 9:02:23 PM EDT

[#1]

Are the feedramps lined up?

Burrs in barrel extension?

Tight chamber?

Will it chamber without a mag in the gun?

Posted: 1/12/2019 9:04:42 PM EDT

[#2]

defective/out of spec barrel extension?

Posted: 1/12/2019 9:34:13 PM EDT

[#3]

Make sure its not binding on the gas tube, that is.....is the gas tube alignment centered?

Posted: 1/12/2019 9:39:54 PM EDT

[#4]

Did you try contacting Smith & Wesson?

Posted: 1/12/2019 9:59:00 PM EDT

[#5]

Quote History

Quoted:
Did you try contacting Smith & Wesson?

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He probably got right through on Saturday.

Pictures would be beneficial.

Posted: 1/12/2019 10:02:25 PM EDT

[#6]

Quote History

Quoted:
Make sure its not binding on the gas tube, that is.....is the gas tube alignment centered?

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My first thought too, make sure the carrier isn’t hitting the gas tube.

Posted: 1/12/2019 10:08:07 PM EDT

[#7]

Quoted:
What am I not thinking of?

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Barrel not chambered correctly.

If it seems to cycle correctly with no ammo but can't chamber a round, and using a different BCG made no difference, it might well be that the chamber is too tight to chamber a round. Either that or the ammo you are trying to use is out of spec - too long.

Take the BCG out and try dropping a round into the chamber just by hand and look at it, compared to another AR. See if it falls out by gravity by pointing the rifle up or sticks.

Posted: 1/12/2019 10:20:24 PM EDT

[#8]

Quote History

Quoted:
Make sure its not binding on the gas tube, that is.....is the gas tube alignment centered?

View Quote

Great point also.

Posted: 1/12/2019 10:22:00 PM EDT

[#9]

Everyone carriers a camera now. Why no pictures?

Posted: 1/12/2019 10:33:19 PM EDT

[#10]

Does it go into battery without a round in the chamber?

Posted: 1/12/2019 11:17:23 PM EDT

[#11]

I’ll try to answer questions from above.....here are some pics.

The gun appears to function flawlessly when I’m not chambering a round.

Sometimes I can get the bcg to go all the way forward....but I can never extract the round without mortaring the rifle.

There doesn’t appear to be an issue with the gas tube clearance.

Bolt doesn’t appear to have any areas of wear.

If I put a round in the chamber without a magazine and then send the bolt home it has the exact same hang up and I have to mortar it.

It goes into battery without a round in the chamber just fine.

When I drop a round in the chamber, it doesn’t appear to go in as far as my rifles. We are talking 1/16 of an inch...which isn’t hard to tell with the naked eye.

Jon

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Posted: 1/12/2019 11:21:37 PM EDT

[#12]

Sounds like his chamber is cut out of spec.

Posted: 1/13/2019 1:32:49 AM EDT

[#13]

Quote History

Quoted:
Sounds like his chamber is cut out of spec.

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+1 sounds like an out of spec chamber. Don't mess with it an void the warranty, send it back to smith.

Posted: 1/13/2019 7:56:33 AM EDT

[#14]

If I had that problem using factory new ammunition not reloads of the correct caliber for the barrel I would send it back to the factory as already mentioned.

Posted: 1/13/2019 8:11:30 AM EDT

[#15]

Had a friend show me his M&P Sport that would not chamber. I went thru the usual diagnostics changing BCG, mags, even put a different bolt catch on.....nothing. Started looking close at the receivers themselves, comparing to some I had. Noticed extra metal in front of the upper that had not been completely milled out and was blocking the BCG. How did this EVER make it out of the factory?? Worst quality control ever, as in none. So if the usual checks don't yield a fix, start looking closely at the milling of the upper receiver.

Posted: 1/13/2019 11:57:33 AM EDT

[#16]

Quote History

Quoted:
Had a friend show me his M&P Sport that would not chamber. I went thru the usual diagnostics changing BCG, mags, even put a different bolt catch on.....nothing. Started looking close at the receivers themselves, comparing to some I had. Noticed extra metal in front of the upper that had not been completely milled out and was blocking the BCG. How did this EVER make it out of the factory?? Worst quality control ever, as in none. So if the usual checks don't yield a fix, start looking closely at the milling of the upper receiver.

View Quote

Another argument for rolling your own AR vs. buying one built by someone tired of being paid $9.50/hr. Yeah, I know...SyW workers are highly paid union workers. That's an even worse excuse.

DO NOT attempt to shoot that firearm! Send it back to the mfr.

Posted: 1/13/2019 11:57:44 AM EDT

[#17]

Scrub that chamber with a chamber brush and solvent, then report back.

Posted: 1/13/2019 5:24:14 PM EDT

[#18]

I didn't read all this extensively, but what I did of it, it does sound like your chamber is too tight. From reading your last post. But savagemann could be right. It might just be a horribly gunked up chamber. Or had some kind of.... something in there that needs to be cleaned out so the round can chamber properly. It would be nice if it was the latter. Because if it's the former, a smith will have to work it over.

Everyone always says AR should just go together when you buy parts and build them but for some reason the one build my BIL did, his chamber was too tight too and needed to be fixed. In theory that shouldn't happen, but I think it does every once in a while.

Posted: 1/14/2019 8:08:33 PM EDT

[#19]

Al good ideas and sigggestions. I ran a bore snake through but will try a brush tonight. I didn’t ask how it was stored or where it was stored. I know he bought it a year ago and never shot it. Since it sat for a year...it could have formed some surface rust or something.

After I reread my original list I realized I never said that it sat unfired for over a year....although the oil Smith ships them with should be sufficient (depending on storage conditions).

If I can’t get it to load after a good scrubbing with a bore brush and solvent...it’s going back to Smith.