what is causing my malfunction?

[corncob]

I'm new to handguns and had three strange malfunctions with my Kimber at the range last night. I've got about 300 rounds total through the pistol so far and I have no idea what could be happening. One time the slide didn't return fully forward. Twice the slide locked back with the last round sitting on top of the empty magazine, which has happened once before. What would keep the slide from returning fully forward and how in the world could the last round get stripped from the magazine and the slide lock back at the same time?

The gun and magazine were clean, by the way, and it is the factory mag, which I'm pretty sure is a mec-gar.

 

[ID_shooting]

I vote bad mag on this one, but 1911tuner will be the voice of authority. On your slide lock issue.

I had in issue with my first 1911 locking the slide at random times part way though a mag. The issue turned out to me my grip. My thumb of my off hand was slightly touching the slide lock and locking the slide back. I changed my grip to a moified weaver and the issue went away.

Boy did I cus that POS 1911 out then had to eat crow when a LEO range coach showed me what I was doing wrong.

 

[1911Tuner]

Burp Trio

Howdy corncob,

The failure to return to battery could be a couple of things. More later.

First things first. That magazine that left the last round sitting on top...
is it an 8-rounder without a dimple on top of the follower?
(Shooting Star and Powermag design)

If it is, it's a fairly common problem, and the round isn't getting stripped by the slide...it's leaving the magazine before the slide gets to it. I did a thread on it somewhere if you want the full description. I'll see if I can find it and post a link. Basically, the inertia of the round is causing it to stand
still when the slide hits the impact surface in the frame, and the pistol is
pulling itself out from under the cartridge. The dimple is there to keep the
last round in the magazine until the slide can get to it.

The fix is fairly simple. A Wolff Extra-Power mag spring will help...if it's
a factory mag or a McCormick Shooting Star...but probably won't completely
eliminate it. If it's a Powermag, it already has the Wolff spring.

The real fix is to get a 7-round follower, complete with dimple, and get a
Wolff 11-pound mag spring. Problem solved.

On the failure to go to battery...look at the case that hangs up next time.
If there's a crescent-shaped mark just below the case mouth, you've got
a light stem bind. If the mark isn't there, either your extractor tension
is too high, or the extractor channel is impacted with dirt or gunk and the
extractor can't cam open easily enough to let the rim slide under it.

Remove the extractor and clean the channel with solvent and a .22 rifle
brush. It should push straight through...and try again. If you get a lot of
crud out of the channel, that's likely it.

If the channel is clean and it still does it. let me know and I'll post instructions for setting the extractor tension.

 

[corncob]

Thanks, I'll look into that next chance I get to get to the range. I suppose the pistol might recoil far enough for the last round's momentum (objects at rest and all) to keep it stationary while the feed lips move backward, eventually releasing the last round--follower moves up, slide locks. The problem with that scenario is that the mag spring would have to be weak enough for the round to slip out, but still strong enough to lock the slide.

Who knows.

 

[corncob]

too late, cavalry showed up

 

[corncob]

It's a 7-round. I'm pretty sure there's almost no extractor tension. It seems very loose--won't hold a round against the breechface. The pistol ejects reliably, though. I've read that a propertly timed 1911 will run with no extractor at all. Maybe that's what's happening in my case.

 

[1911Tuner]

7-rounder

It's inertia...bet on it. I see it a lot with smooth-topped mag followers.
You also may start finding live rounds among your brass. Sometimes
the next-to-last round gets out and lets the last round feed. Maddening
stuff.

Okay, since it's a 7-round mag, it probably has the dimple, unless it's got
a synthetic follower. The magazine spring is probably too weak to nail the round to the feed lips. An overly heavy recoil spring can also be a player.

If you have the telltale stem-bind mark, let it be known and we'll work
through it.

Luck!
Tuner

 

[corncob]

I will.
And thanks.

 

[bountyhunter]

Twice the slide locked back with the last round sitting on top of the empty magazine, which has happened once before. What would keep the slide from returning fully forward and how in the world could the last round get stripped from the magazine and the slide lock back at the same time?

It can be that the mag rides a little high in the frame and the follower can touch the slide stop just enough to catch the slide with a round still in the mag. I have also seen some where the slide stop is too wide and the round can bump it. So, could be mag or slide stop (or an incompatibility between the two).

What would keep the slide from returning fully forward

I assume you mean the round was hung almost into the barrel throat? That usually means the ramp and throat need polishing. That is a VERY common problem on new 1911's. If yours only did it once in 300 rounds, ignore it. Break in will fix it.

 

[1911Tuner]

Inertia!

Here are the mechanics/dynamics of what's happening.
-------------------------------

Newton's First Law of Motion states that objects in motion tend to remain in
motion, and objects at rest tend to remain at rest. Inertia is alive and well
in the 1911 pistol. Start with a pistol in battery with one round in the magazine.

Bang! The slide moves rearward as the pistol begins to torque upward.
The weight of the round in the magazine fights against the magazine spring as it tries to push it upward. The pistol is still moving up and back as the mag spring struggles to do its job of nailing the round up against the feed lips. The cartridge is obeying Newton's Law to remain at rest, and the pistol moves away from it. The spring catches up, and the round is slightly ahead of where it should be in the magazine.

The second shock comes as the slide hits the impact surface in the frame,
and the magazine spring's tension is again overcome, and the cartridge "floats" for a fraction of a second. The impact jerks the pistol rearward and upward a second time, and the round gets even farther ahead of its optimum feeding position. If the magazine spring has seen enough use, the second shock comes before the round can settle into the feed lips. Here is where the round escapes from the magazine, and is left lying loose on top before the slide can get past the stop notch, and is locked open because it has read an empty magazine condition.

If the mag spring is in the twilight zone, the round is still in the magazine, but too far forward for the breechface to make contact, and the extractor hits it instead, forcing the round into the chamber ahead of the extractor.

In some cases, the round gets up in time for the lower edge of the breechface to catch it in the extractor groove, and a rideover feed or a live-round stovepipe occurs.

A heavy recoil spring aggravates the condition, though the reasons are largely theory, but this is my take. A heavy recoil spring causes us to automatically pull harder downward as we fight the effects of the recoil AND the spring. This would seem to have the effect of helping the magazine spring push upward, but appears to have just the opposite effect. I've noticed that dropping to a lighter spring often makes the problem go away, with no other changes. Sometimes simply clipping a half-coil off a recoil spring can make a real difference.

It would also appear that the newer early-release feed lip design allows
a round to escape control of the magazine easier when compared to
the early, late-release "Hardball" magazine design.

Magazine followers without the small dimple would also increase the tendency to let the round escape. The dimple is there to arrest forward motion of a round that is under the effects of inertia, and limit its movement. The dimple, coupled with the gradual release of the round is probably why so many pistols are so reliable with hardball ammo and GI magazines.

I've found that it's far easier to get a 1911 to run reliably with a lighter recoil spring than a heavier one, and I see far less extractor breakage and
need for retensioning as well. Getting the pistol to return to battery reliably with a lighter spring is a matter of proper throat and ramp geometry and finish, and chamber dimensions.

To check for a push-feed condition, look to the once-fired brass. If there
is a small ding near the edge of the rim that sometimes kicks up a small burr on the edge, the gun is push-feeding and the extractor is being forced to snap over. Reloaders will recognize this as case rims that are difficult to
get into a shell holder after a few firings. The dings and burrs will be at the
rate of about one per magazine...usually on the last round.

John Browning was no doubt aware of all this, and he did three things to
compensate for it. He put the dimple in the follower...He kept slide
speed low on the return to battery with a 16.5 pound spring, and
he specified that the extractor be made of true spring steel to allow
for the occasional push-feed with extractor snapover without being
affected by the impact and being cammed open by the rim.

Cheers all!

Tuner

 

[corncob]

After 25 or so leftover range reloads and about 75 WWB, I have decided the failure to return to battery was a fluke. But I had one more instance of finding the last round sitting on the follower with the slide locked back.

At this point I only have the one Mec-Gar magazine, and I am inclined to think it is the culprit. The follower is round and polished, with no dimple, and it's easy to imagine the above scenario happening once every hundred rounds. When the old tax refund comes through, new magazines are first on my list. We'll see if that doesn't fix things.

Thanks for your help everyone, esp. Tuner.

 

[Waitone]

What you described with a Kimber drove me nutso until the welds gave way on the bottom plate of the factory mags. Blew plate, spring, follower and 7 rounds into the floor.

Bought Wilson Combat mags and the problems you described disappeared. Not cheap but effective.