Sidearms & Scatterguns Glock 20 Won't Run

[treillw]

Glock 20
TMT Tactical Full Mod (Slide serrations, stippling, undercut, rmr cut, cerakote)
Tungsten guide rod w/ 20 pound spring (or factory spring)
KKM barrel (or factory barrel)
Zev Trigger
RMR
Surefire X300

Ammo:
200 Grain WFN Hard Cast (Hand Load to Book Max)
200 Grain Hornady Hollow Point (Hand Load to Book Max) - pics of deformed brass
180 Grain RNFP (Factory - General Practice Ammo)
165 Grain RNFP (Hand Load for Plinking)

I think that's all the details on the gun and ammo. Please spare me the don't modify it lecture.

I can't get the gun to run without jamming with any combination of the above barrels and ammo. TMT won't help. KKM won't help. Not sure what to try next. Any ideas? Any good gunsmiths around Montana that can get this thing to run?

It mostly fails to feed. Sometimes it doesn't fully go into battery. The brass is also scraping on the slide ejection port and shaving a good bit off and sometimes with the hotter loads it will actually deform the brass - see pics below.

Thanks.

 

[Zak Smith]

How close to stock and normal ammo do you have to go before it works again?

 

[treillw]

How close to stock and normal ammo do you have to go before it works again?

Nothing works. I put the stock barrel and stock spring back in it and it still jams - at least with the hard cast. I didn't try the 180 grain with that setup.

 

[Zak Smith]

That seems to point to the hard cast bullets and/or load. Try some Silvertips or something standard and see if it runs

 

[treillw]

Last night I tried shooting the hard cast through the stock barrel and stock spring. I think I got 6 rounds through it with no issues. But I can see the lead flaking out of the tip of the barrel. Also can see it in the rifling with a bore scope. Worries me. The bullets are coated - doesn't seem to matter. I loaded more up and switched to the KKM barrel and stock spring tonight - no bueno. Tried the 20# spring - no bueno. Tried 180 grain bullets with the KKM and 20# - no bueno.

I don't recall if I've shot the 180 grainers with the stock barrel and spring - that's probably as close to "normal" as I can get.

 

[Coffee_and_Pipes]

Have you tried a different hard cast round? Mine runs the Underwood 200 grain hard cast bullets without a hitch, but the pistol is completely stock.

 

[treillw]

Have you tried a different hard cast round? Mine runs the Underwood 200 grain hard cast bullets without a hitch, but the pistol is completely stock.

It has issues with the other three projectiles listed, not just the hard cast. I suspect the hard cast isn't the main issue.

 

[GunGuru97]

That sounds and looks like a feed ramp issue. Highly unusual... I take it you didn’t fire the gun prior too modifying?

 

[sam4886]

Have you tried multiple mags? Just one more thing to consider and eliminate as the problem.

 

[Old Man with Gun]

I would test with factory ammo only, reloading issues can easily introduce thess kinds of problems. Trim length, COAL, amount of crimp, etc. I noticed two of your reloads say book max, did you work up to these loads? Did the problems happen with reduced loads? Any pressure signs? How many times has brass been reloaded? Do you use a case gauge on each? Could COAL be changing in the magazine from recoil?

Brass flattened on one side with hot loads is probably ejecting so hard it smacks the slide as it spins from the ejector and extractor. Not an indication of a problem by itself, just shows faster cycle of slide.

What does once fired factory brass look like? What does factory ammo loaded by dropping slide on each round and removed without firing it look like? Any Mark's? Can you do this through multiple magazines with no feeding issues?

Take off the Surefire for now. The Glock frames flex during shooting, a weight on the front rail could be a factor.

How many rounds through the gun? What is the history? Is this a factory Glock 20 that ran before modifications or a never fired parts gun? What generation of Glock is it?

Is the frame Glock or aftermarket? Do you know someone with a G20 that you could swap slides to see if the frame with OEM slide or Slide with OEM frame runs fine?

Factory magazine or aftermarket? Multiple magazines?

Do other experienced shooters see the same problem? Have you eliminated your grip, firmness, etc. as contributing factors? A weak grip, finger rubbing slide, bracing the frame/magazine against fixed object, grip pressing on magazine; all can contribute.

How does it feel when you shoot it? Is the slide slamming back, or short stroking not getting momentum before trying to strip round. Will it cycle 40 S&W ammo? A factory Glock 20 should, if it can not, it may need more break in time or a weaker recoil spring. If the slide is reduced weight it needs to be paired with correct recoil spring.

If TMT took an OEM G20 that ran, modified it and now it has problems with factory ammo, what reason are they giving for not helping? Did they test fire before returning it to you?

Pictures of the gun, failure to feeds and jams, etc. can be helpful.

Keep track of what round of which magazine has a problem so you can look for a pattern. Problems with a full magazine could indicate the slide is outrunning the magazine and a new or extra power mag spring could help.

 

[Captrjc]

A friend had a wilson combat edc x9 5”acting very similar to what you are experiencing. Turned out the extractor had not been filed enough and it was hanging up on the rim and not sliding under the extractor.
A few strokes of a file fixed it all up.

Remove the extractor and lightly Chamfer the edges and confirm that the breech face has no burrs.

 

[Milf Dots]

Cheapest fix is a new extractor. If that doesn't remedy it, then the slide might be a bit out of spec.

 

[M4orturnate]

Have you pulled the barrel and used it like a case gauge. Might be a place to start

 

[flyfisher117]

Go buy some weak 10mm factory ammo. Something like Blazer brass. Put the factory barrel and guide rod in and test fire it.

What part of MT are you in?

 

[JoshPutman]

Some may poo poo them, but try a Lee Factory Crimp Die.

 

[davsco]

yeah i'd put it back to stock, try your ammo, and then swap out one thing at a time. as noted above, plunk your ammo in both your barrels, could be that simple.

i've seen VERY few glocks at matches that have malf's and the VAST majority of those have had stuff replaced, and/or are using handloads which for some reason most folks don't see the need to case gauge or plunk.

 

[John?]

I would look hard at the cereakote to see if it’s causing binding at the extractor or along the slide rails.

Long story short, I had a G17 coated by a well known National shop. The pistol worked fine before coating and choked afterward. Thick coating was the problem and easily cured. Every shoo has a bad day once in a while.

 

[308pirate]

Put it back to stock......

 

[Jrb572]

I know you already said you tried the recoil spring.

But I have a G29 I bought cheap because it would not cycle.

I put it back to stock and it has never had a problem since.

 

[jff_stvns]

I personally would start with the extractor, then swap out slide. Seriously doubt it would be barrel. The way the cases look it seems to point to the shell not being extracted correctly.
I believe in building Glocks but I do not have faith in quality control of parts. I once had a G19 fail to fire with light primer strikes, Imagine that. Turned out to be a out of spec slide backing plate, it did not allow the spring to get its full range so the firing pin can get its full throw to strike primer. I played hell on trying to figure out the issue. I know one thing Lone Wolf makes some bad ass CNC extractors they are sweet. Run them in every Glock I own. I’m confident that one part may be causing the issue. Good luck.

 

[cas6969]

Do you have all the factory parts? If so, pardon me for stating the obvious, but put them all back in and change them one at a time until the problem starts.

I’d also shoot it with only one round in the mag at a time (1+1) and see how she behaves.

 

[7magsavage]

Have you tried a different hard cast round? Mine runs the Underwood 200 grain hard cast bullets without a hitch, but the pistol is completely stock.

Me 2.