1911Tuner
Moderator Emeritus
To address a few magazine-related last round failures, to wit:
Rideover feeds...Live round stovepipe, where the round is nose-up, caught between the breechface and barrel. Slide locked with
the last round laying loose on top of the follower. Push-feed
with failure to return to battery, or extractor snapover.
Note that the stovepiped live round is dangerous. If the primer should pressure-detonate...BANG...two feet from your face.
Inertia, with a couple of contributing factors is at work here.
In slow motion: The pistol is in battery, last round in the magazine. Bang! the pistol starts to rise upward in recoil, and the slide starts back. The inertial weight of the round overcomes the magazine spring for a fraction of a second, and the follower no longer has it nailed to the feed lips. As the spring fights to overcome the round's weight and the upward torque, the
slide hits the recoil surface in the frame. The impact causes the pistol to move sharply rearward while the round stands still...like the old magician's trick of jerking a tablecloth out from under a stack of glasses, and the round gets out of the magazine just as the follower engages the slidestop. In extreme cases, the last round can be launched out of the ejection port.
This is most likely to happen when a magazine spring has weakened, for obvious reasons. What is not so obvious is that, ironically, the early- release type feed lips contribute to the glitch by letting the round escape earlier. Also, a follower that doesn't have a "tit" in the center will allow the round to ride forward to the point that it can escape upward. I've seen magazines with the dimple filed off smooth, with the reasoning that it lets the last round feed more smoothly. That's why the tit is there. The old GI-style late release magazines , along with the tit and a fresh spring will completely eliminate the bug, assuming that the magazine feed lips are correctly formed.
First cousin to the rideover feed, in which the slide outruns the magazine when the tension on the follower is at its lowest point,
the breechface catches the round in the extractor groove or ahead of it, on the case wall.
A too heavy recoil spring can aggravate things. Likewise, a magazine follower without a dimple, such as the Devel 8-round design, and even the Wilson-Rogers follower can cause it. The recoil spring isn't as heavy a contributor as the weak magazine spring, though.
Using a magazine follower with a dimple, and a fresh spring will likely cure the problem.
Hope this answers some questions or solves some problems,
should they ever arise.
Tuner
Rideover feeds...Live round stovepipe, where the round is nose-up, caught between the breechface and barrel. Slide locked with
the last round laying loose on top of the follower. Push-feed
with failure to return to battery, or extractor snapover.
Note that the stovepiped live round is dangerous. If the primer should pressure-detonate...BANG...two feet from your face.
Inertia, with a couple of contributing factors is at work here.
In slow motion: The pistol is in battery, last round in the magazine. Bang! the pistol starts to rise upward in recoil, and the slide starts back. The inertial weight of the round overcomes the magazine spring for a fraction of a second, and the follower no longer has it nailed to the feed lips. As the spring fights to overcome the round's weight and the upward torque, the
slide hits the recoil surface in the frame. The impact causes the pistol to move sharply rearward while the round stands still...like the old magician's trick of jerking a tablecloth out from under a stack of glasses, and the round gets out of the magazine just as the follower engages the slidestop. In extreme cases, the last round can be launched out of the ejection port.
This is most likely to happen when a magazine spring has weakened, for obvious reasons. What is not so obvious is that, ironically, the early- release type feed lips contribute to the glitch by letting the round escape earlier. Also, a follower that doesn't have a "tit" in the center will allow the round to ride forward to the point that it can escape upward. I've seen magazines with the dimple filed off smooth, with the reasoning that it lets the last round feed more smoothly. That's why the tit is there. The old GI-style late release magazines , along with the tit and a fresh spring will completely eliminate the bug, assuming that the magazine feed lips are correctly formed.
First cousin to the rideover feed, in which the slide outruns the magazine when the tension on the follower is at its lowest point,
the breechface catches the round in the extractor groove or ahead of it, on the case wall.
A too heavy recoil spring can aggravate things. Likewise, a magazine follower without a dimple, such as the Devel 8-round design, and even the Wilson-Rogers follower can cause it. The recoil spring isn't as heavy a contributor as the weak magazine spring, though.
Using a magazine follower with a dimple, and a fresh spring will likely cure the problem.
Hope this answers some questions or solves some problems,
should they ever arise.
Tuner