Glock 10mm troubles

flyfisherman246

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May 26, 2017
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#1
I have both a 20 and 29 and each I'm experiencing different problems with.

GLOCK 29SF: I have a KKM fully supported chamber, wolff steel guide rod, 22# wolff spring. I'm using factory 10 round mags with the factory base plate to get the best results. If I put the pierce +0 extension on the mags or shoot a glock 20 mag out of this 29 it jams about once every other mag. This gun jams a lot. Its not limp wristing and I know others are going to say leave the gun stock. I am shooting with this KKM barrel to shoot cast bullets, so I'm not bulging the brass, and it is also way more accurate. The problem I continue to run into is the slide strips the back of the next round just fine, but then for some reason causes the tip to steer up and left lodging into the back of the barrel in the upper left corner. It does this with all types of different bullets and more common in the hotter load levels. I love this pistol for how powerful it is and such a small package, but the damn thing jams most times I shoot it. It also seams to jam way worse with the pearce extension on it too.

GLOCK 20 gen4: This pistol is completely stock so far. I plan on getting a KKM match barrel for it eventually. As of now though, it is bulging brass badly. It has been completely reliable, but with factory s&b and underwood ammo it is bulging so bad it is about to fracture on some cases. As far as handholds go, I started very light with both the 180 nosler JHP and the 220 hard casts with long shot powder and new starling brass. Hodgdon manual says for 180 JHP starting load: 8.5 and max load: 9.5. I started at 8.4 knowing this thing pressures up quickly. Even with this below max load I had bad enough bulging that I didn't go any higher. Also with the 220 hard cast which I shoot 8.2 grains long shot in my KKM glock 29, was bulging/fracturing almost with 7.0 grains in the factory glock 20 barrel.

I have been through the whole "nuclear" load game with 10mm before and lost interest in it. I couldn't get anything to run reliable (I'm thinking due to slide speed) and also don't like having ammo around that could accidentally make its way into a standard glock barrel. So I was working up loads that would be light enough to run in the factory barrels and hopefully maybe get a little more reliablility out of my glock 29. I have gone very light in this testing and still bulging in the glock 20 barrel and still jamming my glock 29.

I know the answer to the glock 20 problem is to get a fully supported chambered barrel, I will do that at some point. But what can I do about getting my 29 to run reliably?

What are your spring/guiderod set ups for you guys shooting warmer lever loads and getting 100% reliability in your glock 20/29's?

Thanks
 

flyfisherman246

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#2
I just cycled a mag through my 29 by hand fast and hard. Every round that cycled through had very similar marks on the mouth of the case and slightly down from there. It makes since its jamming if its hitting that hard every time. Has anyone seen this before? Any ideas on a fix? I wish glock barrels were normal lands and grooves with supported chambers and were designed around heavier 10MM ammo and heavier springs.
10mm.jpg
 

ShtrRdy

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Sep 17, 2011
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#3
Would you mind posting a picture of the FTF condition? From your description I imagined the bullet contracting the back end of the barrel but you picture of cartridges looks like it is contacting the case.

Glock barrels are known for generous chambers to improve reliability. That's why you see case bulging.
 
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101stinfantry

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#4
Someone here recommended this site to me: http://10mm-firearms.com/index.php Someone over there may know the answer to your questions. I wouldn't be happy if my 10mm wouldn't handle full power 10mm loads. I haven't chrono'd S&B, but I doubt that it is a full power load, I know that Double Tap Match, and the Sig fmj isn't. FWIW, I'm running 10.7grs of Blue Dot under a 170gr. Nosler HP @ 1,324fps, but my gun isn't a Glock.
 

101stinfantry

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#7
Just tried hand cycling mine, and while it does leave a mark kinda like your pic, it isn't nearly as pronounced, and just a tad closer to the case mouth.
I also, thought that Glock had fixed the "Glock Smile" case bulging with the Gen III?

ETA: The only thing I can think of on the 29, is the follower isn't presenting the round properly. I'd look into it being a mag issue first.
 

flyfisherman246

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#8
Here is a picture of underwood 220 hard cast factory ammo shot out of the 20. The line looks like its damn near a fracture.

I talked to glock today and they blamed KKM and told me to call them about my 29. I did and they were so unbelievably helpful. They sent me a shipping label fully paid for and said send the whole gun in an they will make it right. If its more than a barrel issue they will take it up with Glock for me. So willing to help and make it right. Have it boxed up and sent out already.

I don't have a picture of the jams I've been getting, but yes, it is slamming into the back of the barrel or right at the edge of the chamber.
 

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101stinfantry

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#9
That is definitely a Glock Smile, it isn't quite as bad as the initial .40 S&W calibers were, but that was before the ammo mfgers started making the cases a tad heavier, and Glock supported the chambers a little better. Still not exactly what you want to see. Just to clarify for me, that round came out of the G20?
 

101stinfantry

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#11
That's really odd that it is doing that, my Dad just sold a Gen III, and it didn't do it with full power loads. S&B lists their 10mm 180gr. load at 1,164fps, it definitely shouldn't be doing that with a mid range load like that. Got me, but there is something up with it.
 

Soulezoo

Sergeant of the Hide
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Jun 4, 2018
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#12
I have a Kkm in my g20sf. It's threaded and I usually run a lone wolf compensator. With that comp, I run stock spring. Un-comped, I run 22# spring with tungsten rod. I use unmodified Glock mags.
I've never had a ftf with any number of rounds. To include factory sig, silver tip, American Eagle, Buffalo Bore and Underwood. I reload "nuclear" rounds using gold dots, XTP, and extreme penetrator. I can't recall my last ftf.
Sorry I can't be of more help.
 

drtyhands

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#13
Man, I'm sorry that both you Glock 10's are funking out.
I have the KKM extended barrels in both my primary home defense 20 and the 29 I use in combat pistol training.
I have run Underwood (Nukes), Sig (Awesome Ammo), Georgia Arms and LAX reloads. Extremely dependable ftf's non issue.
I have not changed springs as others have.

Something trippy is going on,
and I'm frustrated for you as I love my Glock's in 10mm.

As much as you shoot and reload your pistols I'm surprised you haven't spent much time over at Glock Talk on their reloading and 10ring section. I haven't been there in a couple years cause I've moved to perfect other discipline's, hope they are still there.

P.S.
Sorry "Combat" pistol training reads like an extreme poser's terminology and potentially easily misconstrued by pinko's, I don't know which other term to use here.
 
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flyfisherman246

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#14
I used to spend some time over at glock talk and 10mmfirearms forum, but I don't have my password to log in, been a few years. Thats the only reason I posted this here. Well I really do appreciate all the help and glad to hear that most glock 10mm's do run well with other. I'm looking forward to hearing from KKM and what they find out. They were more than willing to help, even if it isn't their barrel causing it.
 

Kevinandcandy

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Jan 7, 2019
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#17
I have both a 20 and 29 and each I'm experiencing different problems with.

GLOCK 29SF: I have a KKM fully supported chamber, wolff steel guide rod, 22# wolff spring. I'm using factory 10 round mags with the factory base plate to get the best results. If I put the pierce +0 extension on the mags or shoot a glock 20 mag out of this 29 it jams about once every other mag. This gun jams a lot. Its not limp wristing and I know others are going to say leave the gun stock. I am shooting with this KKM barrel to shoot cast bullets, so I'm not bulging the brass, and it is also way more accurate. The problem I continue to run into is the slide strips the back of the next round just fine, but then for some reason causes the tip to steer up and left lodging into the back of the barrel in the upper left corner. It does this with all types of different bullets and more common in the hotter load levels. I love this pistol for how powerful it is and such a small package, but the damn thing jams most times I shoot it. It also seams to jam way worse with the pearce extension on it too.

GLOCK 20 gen4: This pistol is completely stock so far. I plan on getting a KKM match barrel for it eventually. As of now though, it is bulging brass badly. It has been completely reliable, but with factory s&b and underwood ammo it is bulging so bad it is about to fracture on some cases. As far as handholds go, I started very light with both the 180 nosler JHP and the 220 hard casts with long shot powder and new starling brass. Hodgdon manual says for 180 JHP starting load: 8.5 and max load: 9.5. I started at 8.4 knowing this thing pressures up quickly. Even with this below max load I had bad enough bulging that I didn't go any higher. Also with the 220 hard cast which I shoot 8.2 grains long shot in my KKM glock 29, was bulging/fracturing almost with 7.0 grains in the factory glock 20 barrel.

I have been through the whole "nuclear" load game with 10mm before and lost interest in it. I couldn't get anything to run reliable (I'm thinking due to slide speed) and also don't like having ammo around that could accidentally make its way into a standard glock barrel. So I was working up loads that would be light enough to run in the factory barrels and hopefully maybe get a little more reliablility out of my glock 29. I have gone very light in this testing and still bulging in the glock 20 barrel and still jamming my glock 29.

I know the answer to the glock 20 problem is to get a fully supported chambered barrel, I will do that at some point. But what can I do about getting my 29 to run reliably?

What are your spring/guiderod set ups for you guys shooting warmer lever loads and getting 100% reliability in your glock 20/29's?

Thanks
Have you checked inside the magazines. Some need to be disassembled and cleaned up on the inside of untrimmed plastic left over from molding process.
 

Sam Dunham

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Jan 22, 2019
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#18
Just curious, have fit several replacement barrels in Glocks. What is the measurement on the KKM barrel from the top to bottom flats in the chamber area Outside distance with calipers compared to the Glock Factory barrel? Did the KKM tighten up the slide to frame fit with no pushdown? I used to take this measurement on any replacement barrel and machine the bottom flat to within .005 to eliminate the friction going in and coming out of battery. Look at the locking block and bottom of the barrel and note any friction marks. A Glock does not have long enough or thick enough rails to really tighten one up to eliminate pushdown totally. They do need to be tight enough to have good sear to striker engagement even if they are a bit loose. My experience with Glocks is that they need to run with very little friction to be reliable and some of these replacement barrels that take up space cause the gun to cycle with friction if not fitted to run close to factory loose. I have seen as much as 25 thou more material on the bottom of the barrel/chamber that needs to be brought into reasonable spec on a milling machine. Another thing is the Hood extension length. If the hood is beating the breech face to lock up tight and the case rim is even with the over length hood? You have a headspace issue. I would check headspace on any barrel I fit with the Customer Pistol individually and make sure the depth was correct with a finish reamer. Most all of them need the Headspace adjusted and some I have seen was a bit oval and some material would come off the sides. I also would take the sharp edge off the top and bottom of the chamber entry and polish the feed ramp. There is no way I would just buy a barrel and stick it in my pistol without going through this process to make sure it is fit properly and the headspace is right. My opinion of replacement guide rods and springs in the case fo the Glock is to stay factory spec.
 

aaron_presser

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Mar 19, 2012
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#19
I would go back to the factory guide rod and spring and see if that helps or makes your failure to feed worse. Might clean mag and or replace your mag spring. Bulging is not a major problem in the big bore glocks normally . By the way how did it shoot in factory form.
 
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Kevinandcandy

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Jan 7, 2019
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#21
Some glocks need lower receiver filed to reduce friction. Our armor filed my lower so it didn’t make contact and added a heavier spring for the hotter loads I was using.
 

Sam Dunham

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Jan 22, 2019
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#22
I would never get on the frame with a file, no need, never have. The locking block is the heart of the lower on a Glock. Check spec on this and if it is within tolerance I see nothing to gain by reducing specs out of a frame (Glock Manu). I am a Glock Armor, was taught by the late Frank Dinuzzo, RIP. The case bulge is the result of high-pressure loads in 10's and in 40's. Some people alter their barrel too much and move the bottom of the barrel throat further forward when they throat a barrel. The case or the carry loads need to be adjusted with a finish reamer to proper depth on after mkt barrels. Stay off your barrel throats with grinding wheels and go lightly not to deepen the bottom of the chamber. Moving the throat further in can even cause case bulge in a 1911 with hot carry loads. Never alter Glock specs to make a non Glock part fit. Work the part to fit Glock specs. Dremel tools in the hands of some people are a mistake. They Muck it up and then complain to Glock. Not saying anyone has done this here, just saying i have seen it before many times in the business.
 
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