Odd malfunction in a 1911

Pretty common, actually. Inertia is the mechanism.

It's called "Jumping the lips" and it happens when the slide whacks the frame before the mag spring has a chance to stabilize the up-coming round, and the pistol's upward torque...combined with the weight of the remaining ammo...causes the spring to actually compress a little.

Once the round is loose, all that's left is for the slide to hit the frame and jerk it backward...and the round is airborne.

It's not unlike the bane of us old gear heads that we called "High RPM Valve Float."

I have read that a heavier magazine spring will fix it. My method is to bend the magazine lips in a little to keep the round from popping out.

A new spring might do it. If Wolff has one listed as "Extra" power for your magazine, that would be the one to get.

Do those Wilson mags have a little "pimple" in the follower? If not, they should.

Jim

Tripp Research makes magazine upgrade kits for the Wilson mags and Tripp Research's mag springs are a good bit stronger than most other manufacturer's mag springs. One of their upgrade kits should fix you up. I've had good success with their upgrade kits.

Isn't that why the good followers have the little dimple? Never been impressed with Wilson followers...

That little speed bump was put there for a very good reason.

listen to Tuner, those Wolff springs do the JOB. This problem IS kinda like high RPM valve float, except that usually wrecked the engine. This problem is easily fixable

I was going to guess that the mag in question was a Wilson Combat with a plastic follower...

Joe

Let us know how it works

Magazine springs generally aren't something to worry about.

On the P12, maybe. I used P14 magazines in my Poly Kimber, and it ate magsprings like crazy until I started only loading 13. Have been using the same wolff extra power springs for ten years. I know for a while (maybe still?) Mec-Gar Para magazines held one less round than OE Paras, something to think about.

My experience with eight round Wilsons (47Ds) has been similar. New springs and followers changed them to 47s (7 rounders).

CMC powermags had the best execution of the eight rounders (until recently) with their folded follower, which added tension that made up for the spring that was short a few coils.

I started avoiding eight rounders altogether by using seven round Metalforms or Checkmates.

Sometime after that, Virgil Tripp stopped refinishing to focus on his CobraMags, which had a longer tube to make more room for that extra round. Wilson came out with the ETMs, which are similar. I haven't used either, but haven't heard anything bad about them.

I still use Metalforms and Checkmates. I blow them out with compressed air. Haven't had them apart, much less change the springs.

The problem is not the spring, it is that darned little "bump." In an effort to make the gun feed more smoothly, some magazine makers eliminated it, not knowing that it was there for a reason. Increasing spring power might do the trick, but at the expense of making the magazines harder to load, plus slowing the slide a bit for the first couple of rounds as the spring increases the friction between the top rounds and the slide.

Jim

Wilsons USED to have a bump.
Early Wilson-Rogers magazines had a steel ball imbedded in the plastic follower, later ones just a plastic hump molded in. It was farther to the rear than a Colt pimple.
I guess they decided you don't need it.
I can't tell if it is necessary or not, I have various non-milspec magazines without pimples and no loose rounds.
I can tell when my Wilson springs are worn, the gun quits stopping open when empty. It is still feeding reliably, though.