I am looking to buy a new model MP 15 sport tomorrow. I can not for the life of me find out 2 things.
1. Does the barrel stay the same width under the hand guard or does it turn into a "pencil" barrel?
2. Does the extractor spring have a rubber O-Ring around it from the factory? ( people say putting an 0 ring around this spring is a must)
Any comments would be appreciated, I am looking to purchase tomorrow and I am on the fence yet. NEWBIE Jitters of spending
$700

Have you been frequenting M4Carbine.......

1. I can't say if it's a pencil barrel under the handguard, but I can say it shouldn't make a hill of beans difference..

2. Same goes for the o-ring, makes absolutely no difference

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Jack C

Mine is .750 at the gas block and under the guard it is .743 , not much of a difference. Do not know any thing about the o-ring you speak of. Some guy put a o-ring on the front pin post to tighten up the lower to upper movement. My 15 does not have that issue.

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Not so Free in the Free State

1. No. It is not a pencil barrel underneath. It's a bull barrel. No grenade launcher mount cut.

2. Yes. The extractor spring has an O-ring.

Most importantly, $700 is a bit steep to pay for a 15-Sport right now. I've seen deals and sales anywhere between $550 and $600. If you're going to pony up $700, might as well get an AR with the prancing pony roll mark on the lower (Colt LE-series).

If you have any other questions, just ask. Welcome to the sub-forum.

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-John

Field strip your BCG. Push out the extractor retaining pin from the bolt. Keep your thumb on the extractor because there is a little spring tension there. Remove the extractor. There's a little spring and O-ring there. The O-ring adds additional extractor tension to ensure that the extractor doesn't slip off the rim of the spent casing.

I've run an AR-15 with and without the O-ring and observed no difference. If your AR-15's bolt had an O-Ring from the factory, leave it there. If yours didn't come with an O-ring, only install one if you have extracting issues.

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-John

Yes there is a o ring and spring under extractor

Welcome to the forum. Lots of good advice (and humor) here. Take some time and research the prices before you shell out $700 for the M&P Sport. Gunbuyer.com sells them for $529 w/free shipping & no other fees. That's where I got mine.Smith & Wesson M&P15 Sport No Forward Assist sw 811036
They're out of stock right now but they replenish their supply quite often. Buds Guns has them for $617 (in stock now) They also ship free but will charge you a 3% fee if you use a credit card. It's your money of course. Just trying to help.

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It's Alive !!