Glock jam / feeding problem

[sdkfz234]

I have a Glock 19 that came with a metal slide. When using green gas (propane), the slide will jam once or twice out of a full magazine.

What happens exactly is that the slide blows back but does not fully return; it stops maybe 5mm short. It appears that the gun is trying to double-feed. There is one BB in the chamber (inside the hop-up) and one stuck between the feed ramp and feed lip of the magazine. This can be fixed by removing the magazine, turning the gun upside-down and racking the slide again to clear the extra BB.

Recently, I've switched to a plastic slide and duster gas. Now the jamming problem is more frequent; roughly 1 quarter to 1 half of the rounds jam. I'm planning to make some "hi-flow" valves out of two valves that I got with the plastic slide.

My question is, what exactly could be the cause of this jamming? I suspect there may not be enough power with each shot, because I can get roughly 4 magazines worth of shots using duster, compared to 2 with green gas. If this is the case, hi-flow valves should help solve the problem.

Another source of the problem could be that the plastic slide is too light and gets stuck somehow when it slide forwards and feeds a round. I highly doubt this though, because the plastic slide is stock for the Glock and should not cause a problem. I can always test this by putting the metal slide back, which should provide more moving mass.

Can anyone provide suggestions or insight into this?

[Kid]

When the slide is returning, it shouldn't be because of not enough gas, could it be that your recoil spring is not strong enough to return the slide?

[p.phresh]

have you tried it with another mag? try to narrow down the problem to either the mag or the gun first. Then you'll have a better idea of what to do next.

[sdkfz234]

Originally Posted by Kid

When the slide is returning, it shouldn't be because of not enough gas, could it be that your recoil spring is not strong enough to return the slide?

I think the recoil spring in fine. Why? Using the hi-flow valves I just made, the gun cycles and functions perfectly with the metal slide. I noticed that the metal slide has a lot less tolerance than the plastic slide (ie. the plastic slide seems to be a very tight fit).

No more jamming issues with the metal slide and duster gas, however the accuracy and grouping of shots seems to have been much better with the plastic slide than the metal one. I'll have to switch back again later and test if this is still true.

[ILL9MIL]

How do the two loading nozzle springs look? when you switched to a plastic slide did they look bent or mangled?

[sdkfz234]

The two nozzle springs aren't damaged. I think the problem has to do with a not-so-good fit between the blowback assembly and the plastic slide.

With no internals installed in the plastic slide, it runs smoothly along the rails, although not as smooth as the metal slide. But with the blowback mechanism installed, that's when it start to stick.

I installed everything back in except the rear slide cover plate so that I could get a better look, and it seems like the hammer is rubbing up against the bottom of the plastic loading nozzle.

The best solution I can think of would to to file, sand or remove some of the plastic in the area where the blowback part sits, to put some more clearance between it and the hammer.

[ILL9MIL]

Are you using an upgraded hammer spring?

[sdkfz234]

No, I'm planning on getting one to go with the hi-flow valves though.