Ran some UW 165 TMJ, UW 180 TMJ, and UW 150 Nosler's today and had failure to feed the last round issues with my factory 10 round mag. So if it's not a mag issue, then what is it? It only occurs with the last round in the mag.

Went to a gun show this weekend with my bud, they had a Glock armorer there.  He took all my mags apart and noticed two things:

1.)  Mag springs on all of them were about an inch shorter than they should be.  He stretched them out from the middle outwards.  I don't store ammo in my mags, I don't even pre-load them before going to the range, and I hardly even load more than 10 rounds at a time.
2.)  Said not to run FrogLube in it, gets into everything (not sure I believe this, I read of lots and lots of guys running it in their Glocks, no problems).  Not only that, but when Glock sent my pistol back, they said they clean and lubed it...and I believe them.  It was very...non FrogLube feeling.  It was like completely dry, not slick feeling at all.  He cleaned it a little with a baby wipe and long q tip, greased the slide rails with Tetra.

So after the gun show we shot and I ran 100rds of the same PBR ammo, 10 rounds in the mags at a time, as I've been running.  1 FTF.  Prior to this I'd have had 10 FTF.  Ran maybe 40 rounds of Underwood 135 and 165 grain.  1 FTF.  Made sure to save some spent brass this time.

He said the springs were supposed to be 6 inches long, starting from the point of the V on the first coil to the end of the spring.

One other thing that I thought interesting:  I don't know how pre-Gen4 mags go as far as the inner workings of the mag, however, he was paying particular attention to what looked like binding of my mags as they got up closer to the top of the mag.  He even went and checked another Gen4 G20 mag he had there, it did the same thing so he pronounced it normal.  But the reason he went and checked was because it did not appear normal to him.  I'd be interested in hearing from pre-Gen4 guys on how the piece the bullet sits on in the mag moves from say an inch from the top of the mag to the top of the mag.  Is there any binding or hangup at all?  It'd be something if these new Gen4 mags that are at least a little different in supporting ambi-mag release have some kind of imperfection in (some of?) them that is sometimes creating a less than smooth progression of the bullet upwards.  Might be another reason to explain why it's just us Gen4 guys having problems...

P.S.  Your March 1st FTF pics look pretty much like what I get.

P.P.S.  I have my own thread and I'm not trying to hijack yours just share info.  Shoot me a PM if you want me to get rid of anything in your thread, don't want to threadcrap.

Quote from: PandaBear on March 16 2014 11:35:50 PM MDT
Ran some UW 165 TMJ, UW 180 TMJ, and UW 150 Nosler's today and had failure to feed the last round issues with my factory 10 round mag. So if it's not a mag issue, then what is it? It only occurs with the last round in the mag.

Curious:  If you take out your mag springs and measure them, starting at the point of the V in the first V of the spring, do you get 6 inches?

One thing I will ask is do you tap the loaded magazine on the palm of your hand or leg to set the cartridges to the rear of the magazines?  I always tap the magazine as to set all my cartridges fully to the rear of the magazines.

Here are things I think about and look for when FTF's are problematic.

As rounds feed from the magazine a few things can happen during the dynamics of operation...
With higher impulse ammo, the next round can be over run by the slide, before it pops up high enough, for the slide to catch it and slide it forward to the chamber's feed ramp.  If the slide doesn't travel far enough to the rear and stay there for a split second to allow the next cartridge to pop up or if the slide bounces at the end of travel in combination with the return can over run the next cartridge.  Recoil springs, too weak/too strong, timing speeds related to ammo impulse.  If springs are bunching up and/or binding up at the end of the stroke that could cause a short stroke of the slide.

If the magazine follower and/or springs are binding or not long or strong enough, that can slow the rise time for the next cartridge to pop up, and it would either stay in the magazine, or be trapped by the returning slide, nose dive or jammed under the feed ramp.

Feed ramps can be a little rough and induce extra drag, hampering the proper feeding.  Cartridge jam against the breech feed ramp.  People talk about not taper crimping except to remove the case expansion, however if a slight taper crimp is applied at the leading edge of the case mouth, this can allow a smoother transition to the chamber.  The cartridge caught on the case mouth at the upper rear of the chamber.

The Cartridge Overall Length, can play into the fully feeding into the chamber, if too long.  The tipping angle can be such that it strikes the upper area of the chamber and the rear of the cartridge tends not to slide up the breech face.  If the breech face is too rough, or the breech face is damaged, the extraction rim can catch or drag not letting it slide into the chamber fully.   Cartridge can be jammed nose up at the barrel's hood.

Also extractors if wrong one is installed, or tight, or damaged, debris build up, can inducing drag, as the extractor rim is trying to slide up behind the extractor, can slow the cartridge from fully sliding up the breech face.  Cartridge short of full feeding.

Reloaded ammo, can exhibit damaged extraction rims from previous use, trapping at the extractor.  Improperly resized case (need to do pass-through sizing) can also cause short of full feeding cartridges.

Frames and or frame rails should be inspected for damaged, if things are not working correctly.

Chucky2,

I appreciate all the information I can get at this time. I really love the gun and just want it to feed the last round as it's supposed to. I measured the spring from my 10 round mag and it came to exactly 6" from the V at the first coil to the end of the spring.

I use Fire Clean for lubrication and I will use the Frog Lube paste with heat and wipe off all the excess occasionally. I've had 0 problems using this method with my other handguns including my Glock 19.

The_Shadow,

I do tap the loaded mag on the palm of my hand to ensure the rounds are properly seated. That was brought to my attention by my FFL. I'd say that about 95% of the time, the last round fails to feed. I have a 10% Wolff spring on the way so I will try it out with my 10 round mag and see if that fixes the problem. I have put exactly 261 rounds of UW through the gun. Thank you for your input.

Panda;

Sorry to hear your troubles.  I am no gunsmith or mechanic but I have a new G20 G4 with ZERO problems of any kind.  At LEAST five different ammo makers through it and 600+ rounds.  The only thing I do is massively clean and lubricate with great products before I ever shoot it.  Maybe just luck but have had almost no problems except a Springfield loaded which had every problem known.  Gun store took it back and gave me full credit for it (rather odd but true).

Best of luck - you have a great and awesome gun there and Underwood is my favorite 10mm company.

Pat

I ran my G20 gen 3 SF with 15 round magazine, 165 grn TMJ underwoods.  Loaded up 6 into magazine, last failed to feed, slide locked to rear.  Did this 3 times.  4 time i decided to practice a clearing drill and actually it was locked to rear without a bullet. 

I had the same problems with my G4. 

I am shooting a KKM barrel.  springs steel rod 21 lb from glockmiester.

PandaBear I e-mailed Glock back and gave them a link to this forum, bumping your thread so hopefully they'll take a look through it also.

Quote from: n2horns on March 23 2014 08:05:35 PM MDT
I ran my G20 gen 3 SF with 15 round magazine, 165 grn TMJ underwoods.  Loaded up 6 into magazine, last failed to feed, slide locked to rear.  Did this 3 times.  4 time i decided to practice a clearing drill and actually it was locked to rear without a bullet. 

I had the same problems with my G4. 

I am shooting a KKM barrel.  springs steel rod 21 lb from glockmiester.

My SF worked fine with the same ammo, stock barrel, and 22 pound RSA from Glockstore.

This may help..

PandaBear,
Please be very carefull of lubing the inside of mags. Any lube getting on the case prior to firing can cause pressure to spike because the case wont fully grab the chamber walls. I use powered graphite on mine and then use air hose to blow out any excess. Hope you get your problems figured out.

I always give my new mags a wipe down with CLP, but that's about it.

Well I returned to the range today after installing a new extended slide release and slide lock spring. Problems continued so I let a RO put a few rounds through my gun and the slide continuously locked back with 1 round left in the magazine.

I will be giving Glock a call this week and let them know about my FTF issues.

Underwood 165 TMJ, 180 TMJ, and 150 Sierra JHP's is the only ammo I've used

Total round count is around 270

Via the e-mails I've been trading with Glock, they use CCI Blazer for testing if you RMA back.  So the question to ask them is:  If I'm using in SAAMI spec ammo that is not mild, but rather, mid to high 10mm power, how are you going to do validation testing to test for FTF?

If they're going to just shoot a bunch of weak CCI Blazer and pronounce the pistol works fine, that's not going to help you (and shipping back to Glock is like $70, not cheap).

Chuck

Quote from: chucky2 on April 21 2014 03:24:11 PM MDT
Via the e-mails I've been trading with Glock, they use CCI Blazer for testing if you RMA back.  So the question to ask them is:  If I'm using in SAAMI spec ammo that is not mild, but rather, mid to high 10mm power, how are you going to do validation testing to test for FTF?

If they're going to just shoot a bunch of weak CCI Blazer and pronounce the pistol works fine, that's not going to help you (and shipping back to Glock is like $70, not cheap).

Chuck

True. If the gun works fine with CCI then Glock is not going to be of help. The next step is to try and tweak it on your own.