SW 1911 FTF on the last round with FMJ

[bouis]

It's strange. I've had the gun for a couple months and put a thousand, maybe 1500 rounds through it, but it's been almost all 200 grain LSWCs, H&G68 style, 1.250" COL, which has been 100% reliable.

But with FMJ it's another story. Every third mag or so the last round FTF. It seems to happen with both WWB and my handloads, all at COL 2.60." It happens with all my magazines, but more often on the ACT and Mec-Gars with the smooth follower. Changing to an 18lb recoil spring and heavier magazine springs didn't help at all.

Slowly walking the slide closed on the last round in a magazine sometimes causes a round to get stuck, where it can't be forced even by tapping the back of the slide.

So I broke the pistol down and decided that there could be two culprits. The slide stop doesn't have any brass or copper on it, I'm pretty much dismissing it (but if anyone disagrees, do say so). The second candidate was the barrel itself. The feed ramp was fine, but the area immediately adjoining it to the up and left, I'm not really sure how to describe it (see pic below), had a pretty nasty burr on it that I guess I'd never noticed before. So I smoothed it as much as I dare with a fine file, but there's still some burr left (see pic 2).

So I put it back together and hand-cycled a few FMJ rounds and, though it seems like it might be better, it still occassionally jams while feeding.

So my question is, should I file or sand down the burr further? Is it okay to remove a little metal there, rounding it slightly? Because that's what it looks like I'm going to have to do.

Or should I ship the whole thing back to Smith & Wesson? I'm very tempted to do this since the muzzle crown looks like ****, and the slide they so graciously replaced previously is a little loose on the frame. Plus, the barrel has some minor tool marks in one of the grooves, that may or may not be perfectly normal, but I couldn't take a picture of. It looks like two scratches 90 degrees from the direction the muzzle is pointing, with an irregular depression in between (but the whole thing fits between the lands and is probably quite small). But sending it back to S&W takes weeks or even months and frankly I don't like the idea of them messing with my gun.

So, what should I do? File and sand the burr off the barrel myself? Send it back to S&W for the free muzzle crowning? *Gasp* take it to someone who knows what he's doing? Something else?

Thanks in advance. -Robert

 

[JoeHatley]

Looks like your breach face could use a bit of polishing. Is the vertical line on the breach face a scratch or is it cut at two different levels?

Joe

 

[Jim K]

Try a GI magazine with a well defined "teat" on the follower.

Jim

 

[bouis]

Thanks for the replies, guys. I have a couple mags with GI followers -- they work slightly better but are still unreliable.

In the picture the breech face is dirty but it's smooth. The vertical line you're referring to is actually the right-angle corner. The powder residue on both sides is probably playing a visual trick on you.

 

[asknight]

What does your extractor hook look like? If you have a burr on your hook, it takes a gorilla strength magazine spring to get the last round under it.

I'm still a little wet behind the ears on 1911's though, so don't take my words as gospel.

 

[1911Tuner]

Last Round Burp

What you have is a failure to go to/return to battery. Since it only happens on the last round, it's probably not a 3-Point Jam/Stem Bind condition, and since the magazine spring tension is at a minimum at that point, that can be a contributor, though not likely the lone player. Most of the time, the extractor is at the root of this particular problem.
From the pictures, that's what it looks like.

Induce the stoppage and press in on the back of the extractor to spring the claw to the right. If the gun snaps to battery, the extractor is the culprit.
Either too much tension...A rough place or burr on the backside of the claw...Sharp corner on the bottom of the claw...
or the backside is too close to the breechface to allow smooth rim pickup...and the reason that it doesn't occur at any other point is because the added mag spring tension is enough to push it past the hang up.

If opening the extractor doesn't let it go to battery...induce it again and use a
length of wood...about a foot is okay...to lightly tap straight back on the muzzle. If it snaps to battery, you have a 3-Point Jam or a sharp corner on the bottom of the claw...or the claw itself is too deep and is bearing on the case in the extractor groove.
Anyway...Run the tests and report back.

Standin' by...

 

[bouis]

asknight, 1911Tuner: Thank you for the reply. I will try that as soon as I get home.

Would the extractor explain why it only malfunctions with FMJ and not SWCs?

Also, do you have an opinion about removing that burr on the chamber?

 

[bouis]

Okay, pushing the extractor in doesn't do anything, but tapping the muzzle with a 1' 2x4 knocks it into battery after a couple taps.

The test cartridge is getting nice, short scratches starting at the rim [of the case mouth] and running lengthwise from doing this. I'd actually call the more like chips or dents.

Edit: erm, the rim of the case mouth.

 

[1911Tuner]

re:

Okay...Sounds like a burr is causing the problem and not the extractor. Polish the burr smooth and don't remove any more material than it takes to get it that way. Only on FMJ/Hardball suggests that overall cartridge length may be a player here, but it could also be the bullet ogive.

This one is probably simple, but may take a little of this and a little of that to get it.

 

[bouis]

I filed a little more off the burr on the chamber and I cycled it about 30 times without it ever snagging. I'm thinking it's fixed, but I guess there's only one way to really find out if it is. Before I do that I need to polish it a tad. Would you recommend sandpaper, and, say a pencil, or a rotary tool and some polishing compound?

1911Tuner thanks again for your help.

 

[1911Tuner]

Polish

600-800 grit "wet or dry" paper on a dowel rod. It's the gray stuff that you can get in an auto parts store in the paint and body work section.
Don't concentrate on one small area and don't remove more than absolutely necessary.

Kudos, lad...Ya done good!

 

[bouis]

Thanks, and again thanks for your help.

I haven't had a chance to pick up some sandpaper and polish the chamber yet, but I can confirm that it's effectively fixed. I brushed the barrel out real good and put about 20 2- and 3-round magazines through it. No jams on the last round at all.

I did get re-introduced to another problem I'd had with one of the Mec-Gar mags, something that only happened with hot FMJ loads (in this case 7.1 grains power pistol). The slide locks after the 2nd to last round and the last round pops out of the magazine and ends up loose in the chamber. Uncool, but I'm pretty sure it's a magazine issue.

The other mag I had with me, an 8-round (the extended type) ACT-Mag, ran flawlessly but occassionally sent the last round's brass back at my face. Not sure what to make of that.

 

[1911Tuner]

re:

Yep. it's usually somethin' simple.

The live round ejection is a magazine problem. Specifically...lack of spring tension. Do a search on "Inertia" for a full explanation. Basically, what happens is that when the slide smacks the frame, it literally jerks the pistol out from under the round that's trying to get into feeding position. Good read, since such a magazine can do a couple more interesting tricks.