HELP! Bolt won't fully close with a round in chamber?

[TerryW]

I have a Smith&Wesson 5.45 upper that I can't get the bolt to fully seat with a round in chamber. Barrel has 5.45 stamped on it so I am sure it's really a 5.45 upper besides a 556 won't chamber at all.

I have the upper off of the lower and sitting upside down on my bench. When I open and close the bolt it fully seats without a 5.45 round in it. When I put a 5.45 into the chamber and try to full seat the bolt it rotates closed only about 90% closed. I can force the bolt closed with the forward assist but then getting the unspent round out I have to use a cleaning rod to push it out while pulling on the charging handle.

Any ideas? I'd like to try to fix it myself before I send it back tomorrow.

(side note) I had to argue with the "tech" at S&W because he told me the upper HAS a serial number.

Thank you in advance!

TerryW

[Guest 6.8 AR]

If a round won't drop fully in the chamber on it's own, check for any junk/ obstructions.

If there are none and your ammo is not the problem, then the chamber needs to be

checked with a reamer, etc. Is this reloaded ammo? Maybe not sized right? Is it a new

upper? Send it back if the chamber is clean.

[TerryW]

6.8, it's a new upper and I am using factory ammo. I've tried more than one round thinking it may be that round. It looks clean inside. It's never been shot and I've run several patches and brushes through it.

I'm hoping it's just something easy I can check myself and not have to wait weeks for S&W to get to it.

Thank you for the response.

Tw

[TerryW]

This is the bolt fully seated without a round in the chamber.

This is as far as the bolt will seat with a 5.45 round in the chamber.

[Westwindmike]

Will a round fit onto the bolt face when out of the gun? Maybe the wrong bolt got installed. Just an idea.

[TerryW]

Mike, I did think of that(surprised I thought of that. LOL). The 5.45 bullet will fully seat and extractor holds tight. Right after I got the upper I took the bolt carrier and bolt out and marked them to keep from screwing that up in the future.

Thank you.

Tw.

P.S. The Westwind is a great jet!

[Guest 6.8 AR]

Take the bolt carrier out and drop a round into the chamber and see how far it goes.

It should fall beneath the teeth. You can check the bolt with the round like that easier, also.

I'd say it need's to go back to S&W if those two ideas won't help. If it isn't the right bolt,

the chamber is wrong(stranger things have happened).

I'll bet it didn't get the final reaming and was a partly finished upper before it was shipped out.

[TerryW]

6.8, that's a great call and that's the problem!!!

With that great idea I pulled the barrel out of the upper then I dropped a round into the chamber and got a rough measurement and came up with almost 2/10" from the primer to the face of the lugs that will engage the bolt. The lugs on the bolt are are 3/10" wide. So it looks like the round isn't fully seating in the chamber by around 1/10 of an inch.

I'll send it back to Smith & Wesson tomorrow.

Guys, Thank you for the help. I didn't want to give the upper to S&W without trying to fix it myself. I'm stubborn like that. :-)

Tw

[Guest 6.8 AR]

Well, I am guessing the manufacturer didn't finish the chamber before shipping

it out. It would be nice to hear from them, but I doubt they would admit it. I

hope I helped and I'm glad you didn't do like I might have: cram it in and shoot!

j/k