New gen 3 Glock 20 SF issues

[Waterboy3313]

I recently purchased a new Gen 3
Glock 20 SF. I literally picked it up on a Friday night and qualified 19/20 for a ccw renewal Saturday morning. First time out for adding it to my ccw I shot 20 rounds through it and shot pretty good in my opinion. First round went a little wonky. I expected that new clean gun etc.

Before I shot it I had some parts on order. Glock store Spring kit, polished Tin coated safety plunger and spring etc. Those parts were installed before ever shooting this new pistol. I went and did my shooting thing the following morning for a 19/20 score and felt like this thing was sweet.

I loaded 2 work up tests for my hand loads and hit the range the following weekend. Both loads were Hornady 180gr XTP projectiles. The only difference was titegroup powder vs power pistol. Factory ammo I purchased and used to qualify was also 180gr cheap stuff. I proceeded to shoot my power pistol work up from factory published load data and felt like I was having a bad day. No groups at all random shot gun pattern like results. Moved to the titegroup load and same thing. Couldn't hit my target at 7 yards. I loaded a mag full of factory ammo that I had used the weekend before with great results and sprayed a mess that didn't group.

Fast forward to today took a friend to the range that is much better than me and is an competitive shooter that does very well. I opened the box loaded a mag and handed him the pistol. He was better than me but couldn't get a group. I tried and did worse and let him try again and he managed to hit the paper.

I'm seriously looking for what would cause the accuracy to fall off that bad that Fast. 20 rounds great then another 30 next week and couldn't tell where I was hitting. I would appreciate any good serious advice.

I did check the slide for any cracks or damage today. I can't see anything wrong or explain what happened.

 

[481]

Glocks are are known for generally being reliable and reasonably accurate out of the box. Since you introduced aftermarket parts, returning the pistol to its original state and firing it for function and accuracy would be a good place to start.

If it groups well, you have your answer.

Don't fix it if it ain't broke.

 

[Hartkopf]

I don’t see how the parts you changed could have destroyed accuracy but it might be worth putting back to stock just to see what happens. Other than that, what does the bore look like? You should be able to run a patch or two through it and the bore be slick as glass.

 

[Dan-O]

Shoot some of the original cheap stuff again at the beginning of a range session and compare notes.

Side note, cheap 10mm is typically watered down 10mm. Don’t know how wild you loaded up your hand loads.

I’m guessing that you’re flinching on your shots, especially if your hands loads were warmish, and the flinch will carry over to just about anything you shoot that day. The aftermarket parts you have listed should have zero bearing on accuracy.

 

[Waterboy3313]

The weird part is that the parts were installed before initially ever firing this pistol. 20 rounds for qualifying were 19/20 and besides the first shot they were all in a approximately 1.5" group.

My only thoughts are first 20 rounds of factory ammo were clean unlike my handloads at the lower end of the charge weights. I always work up from the lowest charge weight in trusted published load data. Obviously the lower end was producing sooty cases. I wonder if the barrel was just nasty enough to cause an accuracy issue.

Yesterday after posting this I did strip and clean the pistol and it was what I would call pretty dirty for having only about a 100 rounds thoughts it. Also during yesterday's range trip I felt I was having a good shooting day from starting with rifles and working back to pistols. I didn't want to ruin my day so this pistol was the last one to be used.

 

[Dan-O]

The weird part is that the parts were installed before initially ever firing this pistol. 20 rounds for qualifying were 19/20 and besides the first shot they were all in a approximately 1.5" group.

My only thoughts are first 20 rounds of factory ammo were clean unlike my handloads at the lower end of the charge weights. I always work up from the lowest charge weight in trusted published load data. Obviously the lower end was producing sooty cases. I wonder if the barrel was just nasty enough to cause an accuracy issue.

Yesterday after posting this I did strip and clean the pistol and it was what I would call pretty dirty for having only about a 100 rounds thoughts it. Also during yesterday's range trip I felt I was having a good shooting day from starting with rifles and working back to pistols. I didn't want to ruin my day so this pistol was the last one to be used.

I don’t clean my Glocks. They’re made to run dirty. I’ve gone 2-3k rounds between cleanings, and the polygonal rifling doesn’t mind nor do I see decline in accuracy.

Most commercial 10mm is loaded at .40 short & weak pressures, unless its the boutique stuff (underwood, double tap, etc).

 

[Waterboy3313]

I also have a glock 17 with the same aftermarket parts plus a 3.5 LB connector. It shoots my hand loads very accurately and I almost never clean it. I bought the 10mm to carry in the woods with my handloads which will probably be pretty stout. I only bought factory ammo because my pickup date was a Friday night and had to be at the range for qualification early next morning. Most of the guns I have purchased over the last 5 years have never seen factory ammunition.

 

[Buzznrose]

Assuming you didn’t somehow damaged the rifling or crown, try this:

Next range trip, bring a couple different types of ammo. Bring a good solid rest for gun, hands, arms. Double up on ear pro. Anything else to stop any possible flinching. Relax…breathe…slow smooth shots at 10 yards.

If the gun shoots fine, it’s probably you. If it doesn’t, I’d check the barrel.

 

[5-SHOTS]

Since I'm sure you haven't lubricated the barrel's rifling, how good is the barrel lockup? Barrel to slide fit at the muzzle? Slide to frame fit? But, most important: check the plastic sights for sloppiness, front and rear.

 

[JohnKSa]

Couldn't hit my target at 7 yards.

How big was the target?

First round went a little wonky. I expected that new clean gun etc.

How wonky and at what distance?

Glock store Spring kit...

What's in the spring kit?

No groups at all random shot gun pattern like results. Moved to the titegroup load and same thing.

Spread evenly in all directions, or was there primarily a vertical or horizontal component to the spread?

Did you save any empty cases from the shooting session? It might be useful to see the primer indents.

 

[The Glockodile]

Process of elimination.

Restart with everything factory, including ammunition - if everything was fine from the get - go.

Then replace stuff one by one, if so desired.

Not trying to be offensive, but money's probably on the springs and the handloads - so introduce those last.

Hope I didn't misread your post...

For what it's worth, Glocks are very tolerant of all sorts of malarkey before they start to misbehave... Ask me why I know

 

[Waterboy3313]

I guess even though it shot fine I will return everything to factory parts (even though it was first shot accurately with aftermarket parts). I wouldn't consider my handloads as part of the factor at this point as the problem exists with the same factory ammo that originally shot good.

My only concern with my handloads was due to starting at low powder charge weight and working up to full power loads. ( low charge weight sooty cases = dirty barrel and other parts) I was wondering of accuracy fell off the cliff due to the extra fouling.

Last and 3rd time out was only the same factory ammo that originally worked fine. I tried 2 10 round magazines. One free hand and one while seated at my rifle bench from a rest. My friend who is a competitive shooter and shoots very well did the same thing I did with the same ammo and was not doing much better.

before the first time it was fired when I had it apart for the spring changes I wiped everything down clean. Ran a solvent patch through the barrel and followed by 2 or 3 dry patches and everything was oiled before assembly. Again at this stage it was accurate.

I don't think it's me the 10mm recoil with factory ammo is nowhere near my 357 H110 max loads. I also shoot quite regularly and feel confident in my ability to do so. Checked everything for loose sights, cracked slide etc. I also use 1inch sticky dots on a sheet of standard sized white printer paper for targets. Sometimes I use 1.5" dots if that's all that is available locally. Targets are on a rigid back board typically set up at 7-25 yards.

 

[MarshallDodge]

I am wondering if the spring change could be affecting barrel lockup in some way.

 

[Waterboy3313]

I didn't change the recoil spring or guide rod. The springs were firing pin/striker, trigger spring, and safety plunger spring and safety plunger. I wouldn't think any of those would change anything with the lock up but I know there are a lot of people smarter than I am.

It's just weird to me that it was working fine with the spring change one day and then not the next. I started off day two with my loads and I know they were dirty in the lower charges at the beginning. I know my other glock does great dirty and I am someone that usually wont clean anything until accuracy falls off. I couldn't imagine it being dirty under normal circumstances at this point to affect accuracy. I did clean it super good just to rule it out at this point.

Weather and timing coming up I'm not sure when I will have time to go try it again.

 

[tarosean]

I’d pull the locking block out and inspect it for cracks or unusual wear patterns

 

[Hartkopf]

Maybe I missed it but how does the bore look? I don’t see how it could have gotten fouled but I also don’t see why it shoots shotgun patterns.

 

[Waterboy3313]

Maybe I missed it but how does the bore look? I don’t see how it could have gotten fouled but I also don’t see why it shoots shotgun patterns

Like I said the only way I think it could have been fouled was by my starting charges. Most of the cases were black and sooty like they weren't sealing as usual when starting at the bottom of the powder spread. I know this caused things to get dirty faster. Was it enough to cause a problem I would like to think probably not but it is a new gun that I don't know and not broken in yet.

Yesterday while at the range I pulled the slide off to look down the bore. My friend that was with me said he noticed something different looking. I can't remember his exact words. But it almost looked like lead fouling to me. Hopefully it's just a dirty barrel.

 

[JTQ]

Perhaps your sights are loose.

 

[Waterboy3313]

Perhaps your sights are loose.

That's actually the first thing I checked.

 

[red rick]

If your reloads were lead your barrel is probably fouled . I would clean the barrel and try some copper ammo .

 

[JohnKSa]

You mentioned that the first round fired from the gun was "wonky". About how far off was it from the point of aim and at what distance?

You mentioned that you couldn't hit the target the second day at 7 yards. Was that target printer paper or something larger/smaller?

You say that the second day another shooter shot the gun. What sort of group sizes was he getting and at what distance?

Were the groups evenly spread (generally sort of bounded by a circle) or were they spread in one direction or another--like stretched in the vertical direction or in the horizontal direction?

Next time you shoot the gun, definitely check the primer indentations to see if they are more or less centered and pretty uniform in terms of how much they are dimpled. Or, I guess since you reload, maybe you could check the ones you have already shot if you saved them.

 

[Waterboy3313]

If your reloads were lead your barrel is probably fouled . I would clean the barrel and try some copper ammo .

They were 180gr Hornady XTPs.