Barrel - Get something with traditional rifling if you want to run unjacketed lead bullets through it. Lone Wolf, KKM Precision, and a few other manufacturers make these. If shooting unjacketed lead ammo is not a priority, then don't bother with this.

Light - Get a light for your gun! You want to carry this while camping, right? How will you shoot 'the thing that goes bump in the night' if you can't identify it? There aren't any streetlights in the woods.

Sights - Along the same line of reasoning, install night sights on your gun so you can hit what you want to kill when it's dark out.

Recoil spring - Most people seem to like 22 lb recoil springs for shooting full power ammo. The stock recoil spring seems to work fine for many people, but keep in mind that the factory weight recoil spring is the exact same as is used in the other full size Glocks, including the G17, G21, G22, G31.

Holster - Your gun isn't doing you any good inside your backpack. Carry it where you can access it. Bears, wild hogs, mooses, and other big animals like to eliminate threats to themselves at their own convenience, not yours.

Quote from: Pablo on July 17 2015 07:34:42 PM MDT

Quote from: t6t0 on July 17 2015 07:31:46 PM MDT

Quote from: Pablo on July 17 2015 05:46:20 AM MDT
It's the ammo, well rather the bullet shape. No doubt about it. In fact, you will notice UW doesn't sell their TMJ 200 or 220 gr 10mm bullet ammo anymore. It was not the OAL, but rather a combination of the length and bullet shape. I like and use UW, but that ammo would not feed in three of my 10mm guns. I could take say 1 each of all the different 10mm ammo I own (over 10 types including my reloads), and in random order fill mags of different guns. Guns, each one, would stop (partially feed) with the UW 200gr (sometimes the 180gr as well)

This is with Glock and S&W and LW and RMW barrels..........(my LW barrel is known tight and it for sure won't take ANY UW)

]

Hmm. I don't think it's the ammo. My original Gen 3 choked on BOTH TMJs and XTP hollow points. My Gen 4 can feed both.

200 grain TMJ from UW? About when was this?

I bought the 200 grain Underwood TMJ a year or so ago and haven't bought it again due to all the jams, so I haven't tested that particular round in the Gen 4. However, the Gen 3 - my Gen 3 anyway - choked on 180 grain TMJ and 180 grain XTP, but both of these - ammo pulled from the same boxes that I used unsuccessfully with the Gen 3 - fed in the Gen 4.

I tend to doubt that it's a matter of Gen 4 being better than Gen 3. I think Glock is just inconsistent with some aspect of their Glock 20s, and I just got a lemon with my Gen 3.

Quote from: Pablo on July 17 2015 05:46:20 AM MDT
It's the ammo, well rather the bullet shape. No doubt about it. In fact, you will notice UW doesn't sell their TMJ 200 or 220 gr 10mm bullet ammo anymore. It was not the OAL, but rather a combination of the length and bullet shape. I like and use UW, but that ammo would not feed in three of my 10mm guns. I could take say 1 each of all the different 10mm ammo I own (over 10 types including my reloads), and in random order fill mags of different guns. Guns, each one, would stop (partially feed) with the UW 200gr (sometimes the 180gr as well)

This is with Glock and S&W and LW and RMW barrels..........(my LW barrel is known tight and it for sure won't take ANY UW)

]

Hmm. I don't think it's the ammo. My original Gen 3 choked on BOTH TMJs and XTP hollow points. My Gen 4 can feed both.

Quote from: pacapcop on July 16 2015 07:44:58 PM MDT
I'll go on record that the issue is the TMJ period. Doesn't feed in Glock barrel.

I did try shooting the same ammo in my Gen 3 that I sold, with a KKM Precision barrel, and it still jammed.

Quote from: Brian B. on July 16 2015 07:55:34 AM MDT

Quote from: t6t0 on July 15 2015 07:11:51 PM MDT
Posting an update: I just picked up my new Gen 4 Glock 20 and put 60 rounds through it using the exact boxes of Underwood ammo that were giving me multiple failures per magazine with my other gun. I didn't have a single malfunction, which I count as a marked improvement. Barring any changes to reliability that result from the gun breaking in, it looks like the issue I was having was a gun issue and not purely an ammo issue. Going to count this as "problem solved."

Was this original Glock new or used when you initially got it? I'm just curious.

I bought both of them new. The original Gen 3 20SF had problems shooting the 200 grain Underwood ammo pretty much right out of the box.

Posting an update: I just picked up my new Gen 4 Glock 20 and put 60 rounds through it using the exact boxes of Underwood ammo that were giving me multiple failures per magazine with my other gun. I didn't have a single malfunction, which I count as a marked improvement. Barring any changes to reliability that result from the gun breaking in, it looks like the issue I was having was a gun issue and not purely an ammo issue. Going to count this as "problem solved."

Thanks for the thoughts. Ultimately, I decided to prioritize ammo feeding. My Gen 3 Glock 20SF can't feed the ammo that I want to shoot, and has failed with several different versions of that ammo, so that gun is sold. I appreciate the feedback from people saying that their Glocks couldn't feed certain 180 grain loadings while the 165 grain ammo worked. However, this gun is for bear and moose protection, so I really bought it to shoot 180-220 grain bullets.

I've got a Gen 4 Glock 20 coming to my FFL this week, so I will be able to test a second gun with this particular Underwood 180 grain TMJ ammo. I will update this thread with what I find. If the second gun fails with the same boxes of ammo that were making my first gun fail, then I'll contact Underwood and try to figure something out. I know you can't return ammo, but I've got like 700 rounds of this stuff, and if a large quantity of it is out of spec, then surely they will want to make that right.

Quote from: DM1906 on July 10 2015 10:09:31 PM MDT
BTW, Underwood and DoubleTap are NOT the same. Not even close.

Would you please elaborate?

Quote from: rw on July 09 2015 11:11:26 PM MDT
Did you buy it used? 
They do not make the regular frame gen 3 20 anymore, think they do still make the sf.
Find a glock armourer and get them to look at it, but i would just send it to glock myself.

It is the SF version, but I bought it more than a year ago in any case. What would a Glock armorer do, do you think? To my knowledge, they are mostly trained to disassemble the gun and swap out parts.

Hello. I've owned a Glock 20 Gen 3 for a year or so, and I've pretty much always shot Underwood 180 grain TMJ ammo through it. It's the least expensive of the full power 10mm loadings and when DoubleTap and Buffalo Bore are 60% more expensive, it seems a logical choice. The problem is that this combination of gun and ammo has NEVER been reliable. At first, I thought that the gun needed a break in, then I thought that I'd just gotten a bad batch of ammo from Underwood (first, I was buying 200 grain TMJs which jammed, so I switched to 180 rain TMJs which seemed to feed better), but the more I shoot the gun, the more frustrated I become.

Today, I was getting failures to feed with both Underwood 180 grain TMJ and Underwood 180 grain JHP (XTP) ammo, both obviously from different production lots - multiple bullet nosedives or other kinds of failures to feed per mag, with multiple mags. I also shot 30 rounds of DoubleTap 200 grain WFNGC Hardcast, however, and didn't get a single malfunction. I've used stock barrel and recoil spring up until now, but today when the gun started to malfunction, I tried out my KKM Precision barrel, both with the standard recoil spring and a 20 lb recoil spring. I got the same kind of malfunctions with every combination I tried. To be clear, the last two times I shot the gun, I was using Underwood 180 grain TMJs, and the last time (when I remembered to bring my video camera to the range to record the malfunctions), I didn't get a single malfunction. The time before that, I got one failure to return to battery per mag. Very frustrating.

My question is, what do I give up on: the gun or the ammo? I'm looking at a couple courses of action:
1) Sell the gun and buy a new one (might try out a Gen 4 Glock 20) or a used one if I can find it for the right price - I will probably take a $150 loss on the deal, but from reports I've read, this could solve the problem.
2) Continue to troubleshoot the ammo, buy a calipers so I can measure cartridge OAL, contact Underwood if the ammo is out of spec, buy more DoubleTap ammo to see if I can feed that brand reliably - I will probably take a $150 loss in all the cost of ammo used purely for testing purposes and may not solve the problem.
3) I do not want to send the gun back to Glock. From what I've read, they don't even recommend using Underwood ammo, so they may not even be able to reproduce the problem at their factory. Add onto that, I'd have no 10mm handgun for multiple weeks in the summer when I do the most backpacking in bear country - NOT an option.
4) Something I haven't thought of?
5) Sell the Glock and buy a Sig P220 10mm instead. 

Thoughts?