Mags dropping when chambering or firing

[bobbo777]

So I'm new to glocks. Bought one of those polymer80 spectre 80% kits and turned it into a glock17.

I am having issue with the mags falling out when I pull the slide back to chamber a round, if it does chamber it drops it after first shot. So trying to trouble shoot.

I bought it from lonewolf and bought a lower build kit from them. It has a lonewolf extended mag catch. The slide is a OEM glock 17 gen 3.

So I milled it out, did some fitting on the slide rails and put the lower parts kit in with little trouble. Gun seemed to function fine, slide was smooth, empty mags went in and out smooth etc..

Then I put in some dummy rounds to test it further and the trouble started. Load the mag pull the slide and the mag falls out, sometimes it would chamber a round or two then fall out but 90% of time falls out first go. Pulled mag catch out gave it a touch with a file thinking it was maybe sticking and no luck. The mag catch seems a little sticky. like it doesn't have much tension on it to pull it into the magazine. Is there supposed to be a lot of tension on the mag release button?

Only drops them with loaded magazines. Empty mags never fall when pulling slide

Also they are gen 4 Glock 10rnd magazines.

So today I took it to the range to test fire it to get it out of my system. Thought maybe live rounds would work better and maybe gun needed little breaking in.

So it kept dropping mags again. Sometimes I could get a couple shots off but either when chambering or firing it dropped out. I only put a couple rounds in the mag. Fought through 100 rounds like this. I try slamming them in and doesn't help and I'm also not hitting the mag release by accident .

So got home took out mag catch/spring and noticed the mag catch spring is slightly bent and on the 2 mags I have therea little chewed up spot right above the mag catch notch. Same on both mags. If I put a mag in with the catch out looks like the notch in mag doesn't line up with the catch hole. its a little low. right where the chewed spot is.

I also noticed that when I load a full or empty mag with slide off and push down on the mag it falls right out and if I grab bottom of mag I can pull it out. But if I push the mag catch into the mag with my thumb the magazine wont fall out no matter how hard I push down. like the catch isn't being pushed into mag enough by the spring.

I'm thinking its either the mag catch or the straight catch pin spring. I ordered a couple catch springs and a Vickers and glock oem mag catch to test out.

Anybody have any other ideas? Like I said I'm new to glocks.



Bobbo773

 

[RX-79G]

Either the mag catch is bad, the mag catch hole is in the wrong place or the bottom of the mag well is too long, pushing down on the mag.

I would try substituting a stock mag release to see if that fixes it. If it doesn't your frame is out of spec. Up to you if you fix it or warranty it.

 

[WhoMe?]

Take the mag release out entirely so it is just the hole. Put the mag in and see how well the magazine slot is lined up with the hole.

 

[bobbo777]

Checked and the magazine notch seems to be 1.5 mm low. The marred up edge of the mag catch cutout is that 1.5mm.
If i push up on mag with my thumb with force it lines up perfect while its being held.

Doesnt look like anything up top is stopping it but the back bottom edge of mag seems to be touching the magwell.

Is it possible need to do little filing in magwell to let mag get that millimeter

 

[bobbo777]

I just took mag catch and trimmed the area that holds the mag a bit and it seems to have done the trick.

Dummy rounds chamber and extract and mag stays in.

 

[FL-NC]

Believe it or not, the floor plates on gen 4 mags are just a tiny bit thicker than gen 3. When I shortened my G17 to take G19 mags, I used a gen 3 mag to mark where to cut. Had the same issue when using gen 4 mags but not gen 3. I had to sand just a tad more off the frame and it was fine for both types of mags.

 

[Acera]

Welcome to the forum bobbo,

How was the rest of the build? I like the idea of a 80% build on a pistol and have been looking at that same design. Unfortunately every time l go to a gun show I seem to be able to buy a good G17/19 from an individual (with no paper trail) for quite a bit less than a build would cost.

Would you do it again?


.

 

[bobbo777]

So after reading FL-NC's post about the floor plates being thick I took a closer look and sure enough it looked like the floor plates were touching just a little on front corners of mag well.

So I took magazine apart and inserted it without a floor plate and it went in deeper so I knew that was it. The polymer 80 has a flared mag and 1911 style grip so bit different than regular glock.

Little filing, shaving and sanding smooth to the mag well later and now mags line up perfectly with the notch.

Ill have to wait till Tues or Wed for the new mag catches to arrive to know for sure but that should fix the issue for good.

In response to Acera.

Building it was pretty easy, It can be finished on just a drill press. Some people just use a dremel.
I used a mini mill which is basically a fancier drill press. basically drill couple holes mill the top and do rear slide rail and your done. Little sanding and filing to smooth it out and get slide to go smooth on your cut rails. I was surprised it was so simple. A glock assembly you tube video later and I was done minus the mag dropping trouble.

Im already thinking of doing it again as you can make a 9mm, 40 or 357 model glock. May cost bit more than buying one in store but Id rather go this route I think

 

[Acera]

Thanks bobbo,

I may take one on as a project if I find a deal on a slide and barrel. That seems to be the expensive part of the build. Got the tools and have some experience with their AR lowers, so not afraid of it.



.

 

[FL-NC]

Glad it worked!