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Slateman 01-25-2013 18:05

4 FTFs with Underwood Ammo
Hey guys, got a problem here. In the last two boxes of Underwood 180gr TMJ, I've had four instances where the primer was struck, but my Glock 20 did not fire. I wanted to post up here to see what could be some causes. I'm loath to immediately blame Underwood, however I have never had this problem with Double Tap and shot a couple boxes in the last 3-4 months flawlessly. At the same time, Underwood Ammo has given me problems

Pics of the strikes

The far left is a round that fired properly. The middle and far right are both FTFs. They are sitting as they did in the chamber. I drew a line with a marker at the top and verified before firing. Took me about a dozen rounds, but I got two. This has happened at least twice before, but single rounds.

Notice how both of the FTFs seem to be to the right, instead of center? What does that mean? Anything?

What do I need to check on my gun?

AA_Khost 01-25-2013 18:40

dm1906 01-25-2013 18:47

A light, off center striker hit is a round that wasn't fully chambered and locked into battery. Could be any number of reasons, including a dirty chamber, expanded case mouth (not crimped properly), oversize bullet, extended bullet bearing surface, or a bullet ogive that starts too slowly forward of the case mouth. This is very rare with almost any round in the OEM Glock barrel, but isn't uncommon with some aftermarket barrels.

With the barrel removed from your pistol, drop the rounds into the chamber. They should fall all the way into the chamber, flush or slightly recessed below the hood, and rotate freely. If not, you need to find out where they are interfering. I color the case mouth (about 1/4" back) and bullet with a marker and force them in by hand. The ink will be wiped from the area of the interference.

The rounds in your pic were not in the chamber like that. They are rotated from their firing position. If you marked them before chambering, it's likely, and common, they rotated while chambering. They won't normally stay in the same orientation going from the mag to the chamber, for a couple reasons. The primer strikes should be either centered like the "fired" round, or high-center. The rectangular dent on the primer of the fired round should be vertical, and can't be any other way. A round going into or out of the chamber can only be presented to the vertical center line of the striker, as the breach is a channel, the round slides up while moving forward into the barrel chamber, and any friction at the case head or rim can cause rotation. It is pulled straight out by the extractor with no rotation.

Slateman 01-26-2013 18:41

This is how the round sits in the chamber:

Also, is this normal for the firing pin assembly:

Is the rear supposed to be slightly off center like that?

dm1906 01-26-2013 19:10

Your striker assy appears normal. The "rear" part is only a plastic sleeve. When installed in the striker channel, the sleeve will be straight, or as straight as it needs to be. If it isn't broken, cracked or deformed, it'll work as necessary. When removed from the slide, the spring tension will cause it to cant slightly toward the striker lug. Your fired round shows a completely normal (ideal, actually) strike. In other words, completely normal. The problem happened with the rounds that did not fire that have the offset strikes. Something prevented the barrel from going into full battery lockup.

Are the rounds (pictured) in the chamber completely engaged? In other words, is the case head below the level of the hood? You can use a straight edge to confirm. Do the rounds go in and fall out easily? Can the round be rotated in the chamber easily, and still fall out freely? Carefully inspecting the case heads, is there any abnormality, such as any part that may be a larger diameter, thicker, or have a gouge (like an extractor mark)?

Also check the forward end of the chamber. Use a scribe or toothpick and scrape the ledge where the case mouth engages. Any fouling buildup (copper, powder residue, etc.) there can prevent full chambering with cases that are near full length.

Slateman 01-26-2013 19:38

They are completely level. I can rotate them freely and it falls out easily as well.

I don't see any marks on the round that are abnormal from the unfired rounds.

I've cleaned out the firing pin channel thoroughly. To be honest, it's probably been 8-10k rounds since it was last done. Assuming the previous owner did it.

dm1906 01-26-2013 20:36

I don't think your problem is the striker. If you had only light strikes, perhaps. But, the strikes are off center, meaning the cartridge wasn't presented in full lockup, the primer wasn't centered in front of the firing pin.

At the very least, with that many rounds through the pistol, the RSA (recoil spring assy) should have been replaced several times by now, and may be due again. While a weak spring can cause FTF/F's, the combination of an otherwise tight fitting round (such as many Underwood rounds) and a weak spring is a recipe for FTF's. Glock recommends about 5K rounds between RSA replacement. In my experience, about 3K is more realistic, especially if the pistol is used for any form of defense, on duty, concealed carry, or home. They are cheap and readily available, so no reason to not replace them regularly.

Slateman 01-26-2013 20:41

Okay. I'll check it tomorrow. If I'm still getting those issues, I'll go with a new recoil spring. I ordered a 20lb with SS guide rod from Glockmeister. Been meaning to get it anyway.

dm1906 01-26-2013 20:46

It may be as simple as that. I've found heavier rounds, such as Underwood, do better with a heavier spring. Others disagree. YMMV.

Slateman 01-26-2013 20:48

What is the "stock" spring weight?

dm1906 01-26-2013 20:59

17 pounds.

4949shooter 01-27-2013 05:48

I had this issue with an early Gen 2 Glock 23. Every once in a while I would get a light strike on the primer and fail to fire. I had the RSA replaced with a fresh one and fired 900 rounds without cleaning the gun (it was a test) and had no issue.

Edit: I will be firing 200 rounds of the Underwood 180 grain fmj today as a matter of fact. I will let you know if there are any problems, but I doubt it was the ammo.

G29SFWTF 01-27-2013 11:45


Slateman 01-27-2013 11:56

Went to the range, fired ~75 rounds no problem. Not exactly definitive, but a good sign.

They did not have a RSA or firing striker spring in stock. Anyone know a place that has them in stock? I have an order in to Glockmeister so I may call tomorrow and see if I can get a stock RSA added in.

dm1906 01-27-2013 12:08

Numrich has them in stock. Shipping from them has always been fast to me. #805620

RYT 2BER 01-27-2013 16:35


qfkeon 02-04-2013 17:12

My new G20 Gen3 was doing this and I contacted Glock. I was told by Glock this is sometimes an issue and they asked me to send them the gun. I haven't had a problem since I got it back.

ModGlock17 02-04-2013 21:00

Slightly off topic. I run my firing pin assembly a little wet with Frog lube. Yours look bone dry. I also polished my firing pin shaft to a chrome shine. They are easier to clean when they are slicky.. FWIW

Slateman 02-05-2013 07:16


Originally Posted by ModGlock17 (Post 19950041)
Slightly off topic. I run my firing pin assembly a little wet with Frog lube. Yours look bone dry. I also polished my firing pin shaft to a chrome shine. They are easier to clean when they are slicky.. FWIW

It's bone dry because I had wiped it off and started the cleaning process. However, I didn't exactly lube it up a lot before re-inserting it. I figure lube will naturally work it's way in there, but I'm usually quite light with the lube.

Got the parts installed in Glock. Figured I'd burn through some ammo to test it. Gone through about 3 boxes with no issues, so thanks for the help. Since I wanted to take pictures, here's some of my work at the range.

Target is 8.5" wide, 11.5" tall. Paper is 11x17
Load: 180gr Underwood FMJ
Pistol: Stock Glock 20C

First pic is rapid pairs at 7 & 12 yards and single shot at 15 yards:

Then I got bored and wanted to see what it was like to shoot pistol with a bench. This is at 25 yards with a bench/chair:

Had three rounds left, and didn't like sitting while shooting a pistol. Single shots, standing at 50 yards:

Honestly, at 50 yards with a 4 inch barrel, I was just looking to hit paper.

In other news, Glockmeister has yet to return an email or pick up the phone.

GRT45 02-05-2013 07:45


Originally Posted by Slateman (Post 19951047)
It's bone dry because I had wiped it off and started the cleaning process. However, I didn't exactly lube it up a lot before re-inserting it. I figure lube will naturally work it's way in there, but I'm usually quite light with the lube.

You are quite correct to leave the firing pin and firing pin channel dry according to Glock's recommendation. On page 79 of the Glock Armorer's Manual, ©GLOCK 2009, there is a big Caution Box with these words in bold print:
"Never leave any solvent or put any lubricant inside the firing pin channel or magazine tube. Along with the breech face and barrel chamber, these areas should be wiped dry before reassembly or use. Leaving solvent or lubricant in any of these areas may cause contamination of primers or powder and possible failure to fire."

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