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Glock 34 Accuracy Problem


frankge

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Having an issue with my G34's accuracy at 25yds.

G34, stock barrel, 13lb ISMI spring on SS guide rod, 4lb striker spring, 3.5 Sherer connector, .25 trigger job.

Took the gun on a rest and the groups are all over the place at 25yds. I tried the following loads

124g Montanta Gold CMJ, 3.8 Zip, Rem SP, Rem Case, 1.125, ~950fps - light load

124g Montana Gold CMJ, 4.5 HP-38, Tula SP, Asst Case, 1.135, ~1060 - USPSA minor

124g Montana Gold CMJ, 4.1 Ttitegroup, Rem SP, Rem Case, 1.125 ~1080- USPSA minor

124g Montana Gold CMJ 4.0 Bullseye, Tula SP, Rem Case, 1.125 ~960 - light load

I've had all kinds of opinions, saying that the barrell might be loose, but all Glocks are like that until lockup, I have also tried an EFK FireDragon with conventional rifling with same results. I'm going to try some S&B Police 124g ammo and also get some Tula and WWB 115's from Walmart to test. I am firing from a full rest with being extremely careful to not jerk trigger or induce any other movement.

Any more ideas, making me nutz.

Edited by frankge
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First have a couple other shooters fire it and compare. This obviously will validate weather it's you and/or the gun.

Describe the bullet impact spread (group size) so we have an idea of what an "Accuracy Problem" is...for you.

Yes. Different ammo will have different points of impact.

Personally, I have not observed a 'inaccurate' modern pistol utilized at practical distances. Meaning 3-20 yards.

Last. Make absolutely sure you are not blinking.

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So I did have another person shoot the gun and I used his G35 .40 to see if I was jerking the trigger. I wasn't. I'm not really worrried about point of aim, that I can adjust for.

Just got back from Walmart and bought WWB 115g, Federal 115, and Tula 115g. I won a bunch of boxes of Atlanta Arms 147's at the ProAm so I'll test this too.

When I mean all over the groups were at least 5" at 25 yds. Some close and some fliers. next range trip I'll post a picture. A question is does a 124g 9mm bullet need to be driven at a certain min. velocity in a Glock to be accurate?

Edited by frankge
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Lots of things come into play, crimp, OAL, powder charge and type.

Try loading out as long as possible and the rounds fit in the magazine should be around 1.140 to 1.150.

Run as light a crimp as possible, should be .002 at the very edge under what the bullet mikes in the case.

Bullet in case .380 then set crimp at .278.

I would load to a reach a power factor of 130 or just a little over, 1040 or faster.

Still get flyers push it a little faster.

If your steady, try a group off hand.

Think you'll like the longer loaded ammo, I did.

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So I did have another person shoot the gun and I used his G35 .40 to see if I was jerking the trigger. I wasn't. I'm not really worrried about point of aim, that I can adjust for.

Just got back from Walmart and bought WWB 115g, Federal 115, and Tula 115g. I won a bunch of boxes of Atlanta Arms 147's at the ProAm so I'll test this too.

When I mean all over the groups were at least 5" at 25 yds. Some close and some fliers. next range trip I'll post a picture. A question is does a 124g 9mm bullet need to be driven at a certain min. velocity in a Glock to be accurate?

How did your g34 group for the other guy? And his g35 for you?

I've found that my Glocks do not group well with conventional rest configuration. It groups better resting the butt on a sandbag rather than resting the barrel/frame on sandbag...

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Powder selection in light loads is a little more than one would think. Light loads will often run into "loading density" issues. I once had an STI Eagle 5.0 in 38 Super. My plan was to shoot IDPA Enhanced Service Pistol with it. Downloading Super to a 125 Power Factor screwed me up big-time. That gun wouldn't hold 15" at 15 yards (No exaggeration). Called STI, they said to send it back. They returned it to me with a test target less than 2" at 25. They shot Major PF out of it. Definitely wasn't the gun.

Given that 9mm doesn't have a large case volume, this is usually not a problem, but I would check some other loads. I would also absolutely check to ensure that the slide is not unlocking just a little bit during the trigger stroke.

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it was a busy range day. tested my g34 bone stock and with the ISMI 13lb, 17lb stock spring, stock and EFK barrels. Stainless ISMI guide rod. Not to mention 80 kinds of ammo. In the end the very best accuracy was the EFK barrel with the 13lb spring.

Some things to note;

115 ammo is not the best for the G34, although not bad they all had larger groups that the best loads of 124g. all chrono's about 1100 to 1150 - WWB, Fed, Tula, and the 124 S&B

HP-38 made PF but the groups were larger like the store bought. I was using 4.5g with a 1.35 OAL

The Zip load running at 920-950 were just bad. I attribute that to me using my Lee scale - ran out of batteries on my digital and only loading 3.8g. However that is within Ramshots load data.

The best accuracy was met with both Titegroup and Bullsye with Titegroup with the, well, tightest groups

124g MG CMJ, 4.1 Titegroup, Tula SP, 1.25 OAL, 1060-1080fps

124g MG CMJ, 4.1 Bullseye, Tula SP, 1.15 OAL, 1040-1060fps

Edited by frankge
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:cheers: I have not been shooting glocks for that long (6 Years) but I have learned a few things. Some simple things to look at is:

Check your front sight, I have had mine come loose before.

Check your rear sight, had a terrible match one Sat and realized my rear sight was shifting back and forth. Drop in a laser bore sight($19.99 or cheaper at Academy or CTD)the one that goes in the chamber.

I am sure your grip is good on the gun but it is something to look at, did you change something and don't realize it.

Worst case could be a crack or weak spot in your lower causing the gun to twist ever so slightly.

Just some thoughts on the matter, hope it may help some.

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