Strange Springfield MilSpec Malfunction

[Tecolote]

My buddy is having a strange malfunction with his NIB Springfield MilSpec . Every fifth round out the mag jams. He's tried 8 different mags and they all jam on the fifth round. The first four rounds and the last three rounds feed great. But the fifth round jams against the feed ramp. It happens with factory FMJ and with his handloads. The same ammo and mags work flawlessly in his other 1911. What's going on?

 

[R.H. Lee]

That's weird. So he's using 8 round mags (the first four and the last three are ok). I suppose he'll have to start eliminating things. How does the 7 rounder that came with the pistol work?

 

[Tecolote]

I need to learn to count. He's using 7 round mags. The first four rounds and the last two rounds feed fine, the figth round always jams.

 

[R.H. Lee]

This is one for 1911Tuner. He'll prolly pick up on this tomorrow.

 

[1911Tuner]

Jam

Weird...

I've had pistols that hang up at random places in the magazine, but never
seen one that does it consistently on the same round every time with every magazine tried except the top or bottom rounds unless there was a
problem with the gun itself.

(Thinkin' out loud)
Well...Since most mag-related problems occur on the top or bottom round, this one about has to be the gun...and since it happens on the same round, it's gotta be a combination of the slide speed and the mag spring tension comin' together at just the right time...or at just the wrong time
to let it happen.

Check a couple things...

Field-strip the gun and lay the barrel in the frame. Push the barrel down
and back. Look at the junction of the top of the feed ramp and the bottom of the barrel throat. The leading edge of the throat should sit forward of the top of the ramp just slightly. About a 32nd inch is good. It can be more, but not less. if the throat is flush at the back with the top of the ramp, or if it overhangs even a tiny bit, that'll hang one up. If the nose of the bullet stops right at the junction instead of farther down onto the ramp...that's the likely place to look. (Do the bullet noses on the jammed rounds have a gough mark?)

If the gap isn't there, the barrel can be set forward at the bottom and the throat reshaped. Not a task for a first-timer. It's easy to screw up the throat if you're not careful or don't have the tools to do it with...ad it could void your warranty even if you do it perfectly. (If you own a Dremel, take it out in the driveway and hit it with a large hammer about 5 or 6 times should do the trick. Might as well eliminate any temptation to use it)

Repeat the check, but this time put the slidestop pin through the frame and the link. Does the barrel lay flush in the bed..or does it stand off the bed even a tiny bit? Leave the arm of the stop hanging vertically and push the barrel down and back with a little pressure against the edge of a table.
Will the stop arm swing freely...or does it get into a hard bind? It should swing freely. If it doesn't, you have a long link. Another shot in the dark.
That condition CAN cause an occasional feeding problem, but probably not as consistently as yours.

There's a small chance that it could be that the extractor has a little too much tension on it...but this is a long shot.

Standin' by...

Tuner

 

[wally]

Are all eight mags he's tried the same brand?

I've seen this with my Springfield "widebody" Micro Compact where the two 12-round mags that came with it would give a nose up jam on the third and fifth shot out of the mag -- meaning a jam on shots 4 and 6 if loaded 12+1 or on shots 3 and 5 if I loaded 12 from slide lock. Never a failure if I only loaded 6 or fewer rounds in the mag with defeats the purpose fo buying a widebody gun!

Fix was stronger mag spring and polishing the inside seam weld of the mag where the single to double stack transition takes place (not an issue with a single stack gun).

I'd try the strongest Wolff "extra power" mag spring before removing any metal from anything.

--wally.


Edit: Forgot to mention, figuring it was a "timing" issue, I first tried lighter and stronger recoil springs as I had them on hand, lighter reduced the frequency of failures but made them more "random", stronger made the situation worse with ocassionally having the slide close on an empty chamber totally missing picking up a round! This told me that the rounds weren't moving up into positon fast enough to feed reliably.