Sig 1911 won't stay locked open after last round

[deckard]

A buddy of mine just got a sig branded 1911. Its pretty new but he's fired over 500 rounds through it. Lately his gun just doesn't stay open after the last round gets fired. Gun is perfectly clean and stuff and the slide will stay open when tested it by hand.

[bonefamily]

Magazine problem maybe?...

[darkroommike]

First thing I'd try is a different magazine. And then call SIG on Monday.

[jad0110]

If it doesn't lock back on various magazines, it might also be a slightly out of spec slide stop / release. I replaced mine with a Wilson Combat unit and the slide locks back 100% of the time now.

[fastbolt]

Is he right-handed?

Is it only happening when he's shooting 2-handed, not 1-handed?

If so, does he favor a 2-handed grip where he aligns his thumbs along the slide (high/neutral grip)? The support thumb can shift so it's pressing downward against the slide stop lever under recoil. This is almost always not felt or noticed by the shooter.

If he's right-handed, does it happen when he shoots the gun left-handed? If not ... that's a clue.

As a LE firearms instructor, I've watched at least my fair share of right-handed shooters exhibit grip techniques that often induced failures-to-lock-back on empty magazines, or early slide lock with ammo remaining in the mag (even using guns with forward-positioned slide stop levers), simply because their grip techniques put their thumbs in the wrong place, at the wrong time, during recoil/cycling.

The shooter influence is often a good place to start looking, since more than 95% of "pistol problems" can turn out to be "shooter problems".

[KyJim]

The most common cause for failure to lock back on empty in a 1911 is the magazine springs. If he hasn't done so, he should dissemble the magazines and clean the springs and inside the mag tube (make sure the top of the follower is NOT lubricated). If the springs are clean, he should try replacing the springs (even then, mags eventually wear out).

The easiest thing to check, however, is the grip. As fasbolt has indicated, a thumb on the slide stop lever when shooting (thumbs forward grip) can cause this. It doesn't happen with all 1911s. For example, I have several 1911s but only one where I have to really watch this.

Also, take the slide off and look to make sure the lip of the magazine follower is actually engaging the follower on the inside of the frame (it should "just" catch it). A mag might begin by catching it but then, after a bit of wear, might miss it.

[polyphemus]

"the slide will stay open when tested it by hand."
OK then,it doesn't happen to have one of those rubber washers that
some folks insert on the guide rod does it?
Barring that if any magazine you try shows the same result,look at the slide stop
follower engagement(no need to strip here) it should be positive as opposed to
barely catching.Other than shooter interference you are probably looking at
a new slide stop.

[reynolds357]

above mentioned are all possibilities. I have seen limp wristing a 1911 cause this problem on rare occasion.

[HiBC]

A recoil spring is not real hard or expensive to change,or maybe some zippier ammo.

I have a Commander clone I just did some work on.I put a stock rate 18 lb spring in it.Same problem you are having.Bought new Colt mags and plus 10% wolf mag springs.That helped a lot,but its not 100%.I'm about to order a 17 lb and 16 lb spring.

The ammo at this point is WW white box Walmart promo ammo.

When I try or load some stiffer ammo,I can go back to 18 lbs.

[James K]

How about ammo? If the ammo is underpowered, the slide might not be coming back far enough. The gun will extract, eject and reload OK, but the slide needs to come back just a bit more to lock open.

Jim