Glock 21SF light strikes

[jetfire]

My backup to my Gen 4 Glock 21 is a 21SF. I bought the gun used from a friend who had put a significant number of rounds through it a few years ago, and then it had mostly sat in his safe. The past week I decided to actually shoot it to make sure it worked, and imagine my surprise when shooting Aguila 230 grain ammo I had two light primer hits. Further testing with TulAmmo .45 and Hornady steel match had no light hits with those rounds, so I figured the Aguila primers might have been hard and didn't worry about it.

Until yesterday; where I used my 21SF instead of the Gen 4 for a practice session. The 21SF has a slightly different sight set up, and I wanted to try it when shooting with both eyes open and see if it was better (it was). However, I experienced multiple light strikes with TulAmmo .45 ACP and Hornady Steel Match. So the gun came apart and I vigorously cleaned out the striker channel and the firing pin assembly. I also ordered another firing pin spring just in case that doesn't work.

Beyond that, are there any other things that may be causing light strikes? The striker assembly is stock, no lightweight gamer parts or anything like that.

[voodoo_man]

Clarify something please...

you say its a gen4 and your friend put rounds through it a few years back? I have a gen4 glock 21...only got it less than a year back when it first came out..?

Also if its an SF is it a gen 3? What are the first three of the serial?

[F-Trooper05]

He said the SF is the backup to his Gen 4.

[voodoo_man]

He said the SF is the backup to his Gen 4.

misread, my fault, apologies.

Agulia sucks, btw.

[jetfire]

Yeah, the 21SF I bought to backup my main match gun, which is the Gen 4. I have had zero problems over 5K rounds with the Gen 4 21. The 21SF had the aforementioned issues with light primer hits.

[WDW]

If it only happens in that one instance I would let it fly. If it happens again I would replace the striker spring although I'm sure I'm not telling you anything new. Also, maybe detail strip the slip & degrease. It may have some lube built up in there from sitting so long, maybe some crud or something in the striker channel? I run a G21SF from time to time & I haven't had a light strike before with it, not that that means anything. I've got probably around 3,000 or so rds. through it.

[jetfire]

I ended up having several light strikes in one practice session, so I vigorously cleaned the striker channel and assembly. I'm just trying to think of other things that may have caused it if this doesn't work. I did order a new striker spring, which will be the next thing I replace.

[BigT]

I cant remember if it proceeds the SF but is the number on the trigger bar 4256 or 4256-1 ?

If its not -1, a -1 trigger bar should help.

[jetfire]

It is a -1 trigger bar, just looked at it.

[BigT]

No damage or flattening to the tip of the striker?

I know it sounds obvious but it can be missed if you dont compare it to a newer one.

[jetfire]

Actually, I never looked. I'll probably do that later today although it appeared to be fine when I was detail stripping it.

[BigT]

My one G17 has needed a new striker every 20-25 000 rounds. IThey flatten and shorten and start light striking.

[jetfire]

I think I found the problem. Check out the springs:

689

The new replacement spring is on the left, and the old spring is on the right. It's about a coil length shorter than the new spring that I just installed. The trigger pull is noticeably heavier now, but if that's the trade I have to make to get 100% ignition it's totally worth it.

[DonovanM]

So aftermarket spring then (finish looks different) or just a crapton of rounds/dryfires through it?

[jetfire]

A crapton. I wasn't the first owner of the 21SF, the guy who owned it before me shot even more than I do and used this for almost an entire season.

[JBP55]

The new spring is an OEM Glock 5.5# spring and the old spring is an after market spring and is probably a 4# spring.

[jetfire]

I talked to the original owner of the gun, and he said the right spring is an OEM Glock spring that's seen some hard use. The right spring is almost 5 years old and has seen a lot of rounds, dry fires, etc.

You are correct that the left spring is an OEM Glock spring.

[BigT]

I cant remember ever seeing an OEM silver spring go that colour. I have seen lots ofaftermarket spring that colour.

Not possible he forgot an insignificant part change?

[jetfire]

Possible, but not likely. If you'd like the full details, PM me since some of the stuff about the gun isn't for public disclosure.

[JBP55]

I cant remember ever seeing an OEM silver spring go that colour. I have seen lots ofaftermarket spring that colour.

Not possible he forgot an insignificant part change?

I concur.

[JohnO]

I would not completely rule ammunition as a possible cause. Primers not fully seated in the pocket very often will not detonate on the first attempt. They move forward in the pocket thereby negating much of the energy imparted by the striker. Second attempts at firing the same round usually are successful.

I see it mostly with reloaders who are not diligent with primer seating. However I have seen numerous times with factory ammo in the last few years. I have attributed it poor quality control.

You may have identified the problem with the spring you recently replaced but keep my thought in mind if you see the problem again.