Polymer 80 "Glock" problem

[Cowboy_Dan]

I finished my Polymer 80 Glock 17 build over the weekend and took it to the range today. I brought with me a set of cast loads to test and a handful of factory fmj's to start it out with a function test.

Problem arose first time I pulled the trigger, failure to eject and the slide did not go into full battery with the empty still in the chamber. I clear it, and the next one ejects fine, but the slide hung up defore going into battery again. Push the slide forward with my thumb, and same thing again, and again, and again for all 10 factory rounds. There was 1 stovepipe and 1 failure to feed.

Any ideas as to the cause? Any time I rack the slide it closes up tight, but under recoil it has stopped a smidge short 10 out of 10 times. Thanks in advance.

[244]

Have you tried to shoot it with only one round in the magazine? Load the mag with one round and chamber. If it doesn't lock back (assuming good mag/mag spring/follower and new recoil spring), it is hanging up somewhere. Perhaps some hand cycling or more oil on the slide rails and tabs would smooth it out if you don't want to use very fine sandpaper. Try a good bit of oil over all metal surfaces to see if it helps.

Is the barrel hood locked to the slide when it is out of battery?

Is it a new upper half, or is it used? Is it Glock or aftermarket? Do you have another suitable Glock to swap and see if that helps?

[retrobass]

Does it pass the battery test? Point it straight up, dryfire, keep trigger to rear, slowly release slide (holding tension and letting recoil spring do all the work). Slide may not return all the way to battery, but it should snap into battery as you ease the muzzle of gun toward horizontal (hand off the slide at this point). The standard is a full return to battery by 45 degrees.

My G23 Poly 80 had two issues causing return to battery troubles. First thing to be addressed is that I needed to remove more material from recoil spring assembly channel. It's tight in there, so there should be absolutely nothing for spring to hang up on. Get it to a smooth finish with 600 grit inside this channel.

I also had to remove a tiny bit of material from the trigger bar that depresses safety plunger. Diagnosed this by looking through mag well slowly working slide by hand. It was hanging up as this tab on trigger contacted the slide, particularly if I was riding the reset. A run of Glock 30's had a similar problem from the factory at one point!

It goes without saying that you should also generously apply oil to the rails and cycle by hand several hundred times. Mine goes into battery perfectly no matter what now, but nonetheless I'm using a 20 pound ISMI recoil spring for the first 500 rounds of break in. Can't be too careful about avoiding the ol partial out of battery KB.

[Cowboy_Dan]

Have you tried to shoot it with only one round in the magazine? Load the mag with one round and chamber. If it doesn't lock back (assuming good mag/mag spring/follower and new recoil spring), it is hanging up somewhere. Perhaps some hand cycling or more oil on the slide rails and tabs would smooth it out if you don't want to use very fine sandpaper. Try a good bit of oil over all metal surfaces to see if it helps.

Is the barrel hood locked to the slide when it is out of battery?

Is it a new upper half, or is it used? Is it Glock or aftermarket? Do you have another suitable Glock to swap and see if that helps?

I have tried it with one round in the magazine exactly once, on the last of the factory rounds I brought. That was the one that stovepiped, so it did not lock back. I talked to my brother about this after I posted, and we noticed a squeak on the guiderod. I added a little oil to the new Glock OEM spring and the sound stopped. We think this was at least part of the problem.

There is bicycle grease on the engagement surfaces between the slide and the frame, including a light coating where the trigger bar engages the firing pin safety plunger (not positive my terms are tight here, but they should be sufficiently descriptive).

I didn't check how far out of battery it was, but as I hand cycle the slide it seems that the hood (this is the square portion at the back of the barrel, right?) does not lock up until full battery. The upper half is new, barrel and slide by Combat Armory, internals purchased as a kit from Lone Wolf. I don't have another slide handy to try, we don't have any other Glocks at the moment.

Does it pass the battery test? Point it straight up, dryfire, keep trigger to rear, slowly release slide (holding tension and letting recoil spring do all the work). Slide may not return all the way to battery, but it should snap into battery as you ease the muzzle of gun toward horizontal (hand off the slide at this point). The standard is a full return to battery by 45 degrees.

My G23 Poly 80 had two issues causing return to battery troubles. First thing to be addressed is that I needed to remove more material from recoil spring assembly channel. It's tight in there, so there should be absolutely nothing for spring to hang up on. Get it to a smooth finish with 600 grit inside this channel.

I also had to remove a tiny bit of material from the trigger bar that depresses safety plunger. Diagnosed this by looking through mag well slowly working slide by hand. It was hanging up as this tab on trigger contacted the slide, particularly if I was riding the reset. A run of Glock 30's had a similar problem from the factory at one point!

It goes without saying that you should also generously apply oil to the rails and cycle by hand several hundred times. Mine goes into battery perfectly no matter what now, but nonetheless I'm using a 20 pound ISMI recoil spring for the first 500 rounds of break in. Can't be too careful about avoiding the ol partial out of battery KB.

Not exactly positive about your meaning on the return to battery test, but here is what I just tried based on what you wrote. I racked the slide (no magazine, gun checked out as empty), pointed muzzle up and dry fired. Holding the trigger to the rear, I pulled the slide back and used my hand to slow its process allowing the recoil spring to pull the slide forward. With the muzzle pointed upward, the slide would not return to battery. Continuing to hold the trigger to the rear, I lowered the muzzle to horizontal. The slide did not budge on the way down, bit as I released the trigger it jumped into battery. Tried the same process again, but released the trigger with muzzle verticle and it rode my slow relase into battery.

I just looked and did notice a ridge in the recoil spring channel which a spring coil could catch on. I'd probably eyeball it at .010", maybe more. I can break out a half-round needle file to clean that up.

As said above, there is grease on the slide rails and such. The slide has been hand cycled tens of times, probably about 100-150, so more may be in order. Regarding the out of battery kaboom, it appears this one will pull the slide forward (if possible, of course) if it is out of battery and the trigger pulled. Firing pin seems to not drop out of battery, but only tried that conciously with an empty chamber.

[244]

Does your firing pin/drop safety operate smoothly? The vertical extension of the trigger bar engages it (silver plunger on bottom of slide) when the trigger is pulled. It almost sounds as if it is hanging up and when you release the trigger it moves out of the way enough to go into battery in your hand cycling tests.

You should be able to compress the plunger and tension on the striker will be relieved. The striker/firing pin should be able to move a slight bit in its channel and extend past the breech face with the plunger depressed. Check the vertical extension and make sure it is smooth. There also MAY be a dimple on the trigger bar that MIGHT be hindering movement. Check the trigger bar and slide/frame for spots of friction.

Lots of hand cycling may make the problem go away too as retrobass mentioned.

[Cowboy_Dan]

When the firing pin safety is pressed I am able to push the firing pin forward, but I have to push it. Gravity will not pull it down with the removed slide oriented muzzle down. When I pull the pin back beyond a certain point the safety re-engages. Just checked again, sometimes gravity will pull the firing pin down.

I did notice while I had the slide off that there is a line on the slide directly above where the vertical extension of the trigger would be as the slide moves. Would this be causing enough friction to cause problems? I also noticed a few flecks of copper stuck to the slide, not sure about those but they aren't near the trigger bar's path, so probably not part of the problem.

[Cowboy_Dan]

I just did the slow hand cycling while looking in the magwell that 244 was talking about. I did see the vertical extension of the trigger bar dip down as it left the ejection port. Maybe mine is a bit too tall too?

[retrobass]

Absolutely get that 10 thousandth removed from your recoil spring channel before you do anything else. Then you can work the trigger bar down with some sandpaper a few thousandths. If you go too far, the gun won't fire. If you're worried about it, proceed with a little Glock Armorers half plate on the back of your slide. Google 'Glock 30 return to battery trigger bar' and you will find talk of a similar problem. I didn't have to remove much material at all. I also used mothers magwheel polish to smooth out the safety plunger and the top of the trigger bar.

[244]

Cowboy, go slow as you cannot undo what you did without buying new parts.

I would suggest to check the work YOU did on the frame first before modifying your slide or frame parts. Do not leave out the hundreds of hand cycling repetitions either as these may solve your problem without other modifications to "factory" parts. Just rack and release without evaluating every cycle. You are basically polishing by hand cycling and that may do it for you.

If you field strip the pistol and secure the slide by pinching the firing pin safety, you should be able to shake it and the firing pin move. If it hangs up, there may be debris in the channel of the firing pin or plunger, requiring you to strip the slide to clean. It is easy and I'm sure there are youtube videos showing how, but let me know if you need help.

[W.R.Buchanan]

Don't mess with the factory parts! They are right. You probably need to smooth out your rear guide rails.

Randy

[retrobass]

Ever get her working?

[Cowboy_Dan]

Sorry, guys, hqven't had a chance to do much work on her yet. Just got switched to night crew and the change in sleep schedule is still getting to me. I have Monday (night) off, so I may get some work done then and retry her at the range soon after that.

[Cowboy_Dan]

OK guys, I have done a few hundred hand cycles (I try not to do too many when everyone else is trying to sleep). Every couple hundred I retry the reurn to battery test as outlined above. Before I started, I decided to see just how low I had to get the muzzle for it to return to battery on its own, and it has since improved from taking 225° (45° past straight down) to 135° (45° below horizontal). Beyond hand cycling it another 1000 or so times, is there anything I can look for to figure out what it is holding it back?

Mr. Buchanan suggests it's the rails on the frame, could some one maybe measure theirs and tell me how thick their horizontal part is and how deep the cut out below is?

[billyb]

My son assembled one of the 80%er's and had the same issue as you. Like stated above he had to polish the rear slide rails on the under side, there was a lot of drag on that area. He used one of my diamond hones to polish it out, only took a little to get it to function.

[244]

Have you test fired again Cowboy? If so, was there any improvement?

[Cowboy_Dan]

I continued working on this project for a while with little improvment to return to battery tests.

Monday night, I saw a video on You-Tube about my issue. It showed that some models have excess clearance around the trigger mechanism housing and that shimming it resolves problems like mine. I had noticed that when reassembling the pistol that the slide would hang up on the plastic behind the ejector, so I decided to try it. A hunk of paper from a piece of junk mail later and the reassembly hangup is solved.

I also polished that bit of plastic and some spots on the locking block that showed wear. I did take a couple of swipes with 600-grit sandpaper at the top of the verticle extension of the trigger bar to remove a sticky-uppy that shouldn't have been there. At this point, it passes the return to battery test 5 times in a row. Time to head out to the range for ...

Test #2:

I went to the range this morning bringing a 100 pack of Federal 115 fmj's. Started by loading one at a time from the magazine. Out of 12 such shots, only the 2nd failed to lock back the slide, no other malfunctions.

Remainder of the box was shot with magazines loaded with 8-33 rounds, mostly 10 each. Did not keep count, but failed to eject only a few times, maybe 4, and one double feed clearing a failure to eject. Slide locked back after every magazine. Over the course these 88 rounds, it failed to enter battery twice, once each on the first two magazines. I checked with my thumb after every round.

Any further questions, comments, or suggestions are welcome, thanks again.

Edit to add: I noticed that the external lips of the magazine have scratch marks from the slide moving . Are they indicative of anything? It is an Glock OEM 33-round magazine. Only magazine the local store had in stock at the time. Didn't want to mess with getting standard size ones until the issues are resolved.

[retrobass]

It sounds like your slide is riding too low. I'd try another OEM Glock mag to make sure it's not something going on with the 33 rounder. Here's a cheap 10 rounder (regular capacity out of stock):
http://www.combatarmory.com/glock-17...agazine-gen-4/

[Cowboy_Dan]

A couple of standard size OEM magazines arrived today. I haven't tried them out at the range yet, but I did take the slide off and line up the various magazines with it. When alligned with the slide as though inserted for use, the 33-rounder tightly contacts the slide while two different 17-round models had space to wiggle side to side. Makes me think that the 33-round magazine has wider outside lips causing the scratch pattern. I could be wrong, I guess I could do some measuring.