Deteriorating accuracy!

[3djedi]

Well, I went through everything and didn't find anything out of the ordinary.

I'll try factory ammo tomorrow and if it still off then I will have somebody else shoot it.

Edited July 18, 2014 by 3djedi

[SilverBolt]

After about 20k rounds my groups started to open up on my Gen-4 34's. Replaced the lock blocks on both and they tightened right back up.

[jimreed1948]

Someone mentioned about broken parts. This could be it. It was for me once. When the problem started I did what you did. Problem continued. I found someone that had a Ransom rest and it did the same thing. Stripped the pistol down to nothing and found a cracked locking block. Replaced it and went back to the Ransom rest, problem solved.

Some ranges may have a Ransom rest you can rent for an hour or they may know someone that has one you could contact. Since that time, I purchased one and that's what I use for my new rounds. No more flinching, bad grip when shooting, etc. I just considered the Ransom rest part of my reloading tools.

[Moltke]

Has someone else shot the gun and blown the center of the target out yet? Or is this still a mystery?

[3djedi]

Oops. Sorry about not following up. It's my reloads. I haven't figured out what is going on with them though....

I tried some factory ammo and got great groups.

[Moltke]

Oh, I also figured it was your trigger control because of the low left stringing but glad the problem is identified.

I'd focus on OAL first because you said 1.15" and thats probably a bit long for a factory Glock barrel.

You'll notice that many factory ammo's are loaded to the small side of SAAMI so they chamber easy in every gun.

Measure a factory round to see what the OAL is and you'll see what I mean.

To figure your optimal OAL,

Get your barrel in hand, drop in your 1.15 OAL load, and does it spin freely? If not, thats because its touching the rifling.

Reduce it to 1.14, 1.13, and so on until the round can be dropped in but still spin freely.

Load to the new OAL and try again, maybe you'll have better results this time around.

Continue to tweak it until you're happy with your results.

Edited July 30, 2014 by Moltke

[3djedi]

I think the problem was under powered load. Cfe pistol seems to like high velocity high pressure.

I tried reducing the OAL to 1.125" and increased charge by .2g. It seemed much better out of my new tanfoglio but I haven't had time to try in the glock.

[Moltke]

1.125? Is that what the factory ammo measured at? Seems quite a jump from your previous load to be random

[3djedi]

Actually, yes that was the length of the factory ammo. But the reason I jumped to 1.125 was because this was the length used in the load data for my bullet. I really need to chrono.

Edited July 31, 2014 by 3djedi

[Moltke]

I'm sure that will help you alot, good luck in solving the problem

[Steve RA]

Less than $100.00 on Amazon for Competition Electronics. I'm an Oehler fan, but also have the CE and it's way better than 20% of the Oehler.

[3djedi]

Oops....mistyped. I actually have a CE with indoor lighting kit but I'm only a member to an indoor range and still working on getting permission to set it up.

But I have used it in the back yard with an airsoft gun so I know it works. Lol

Edited July 31, 2014 by 3djedi

[rdinga]

Had a local gun shop install a set of Heine sights on my glock 17. While at the range my groups went crazy. Got home and noticed the front sight was not installed properly. After glock armorer s cleaned up the mess, groups magically shrink back to normal

[grouptherapy]

Checking the headspace with the barrel is the best advice I've seen although there are lots of good posts here. I'd try the drop in the barrel then knock .010-.020 of that making sure you don't go under min oal. My 115 factory ammo came in around 1.162. Bought some sns125 poly coated bullets and a lwd 40-9 barrel and had to shorten it down to 1.080 b4 it loosened up in the chamber. Each barrel is different. Accuracy is nicer for me when I ck oal to each particular barrel. I chrono too to Mae sure the FPS is ballpark but cycling and accuracy along with no pressure signs take precedence over every thing else. Just my experience. Good luck and btw don't over crimp.

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[Mayonaise]

You can't just load reloads for power factor. Once you have PF, you need to test and adjust for accuracy. It's time consuming but as you have found out, well worth that time.

BTW Locking blocks are MIM, if they fail they usually fail early in life, like almost right away. Unless you have an overpressure issue which can break them and or the locking block pin among other things.