POI Shift with Reloads

[TalkingMonkey]

I started reloading about a year ago and have loaded and shot around 7,000 rounds since then. So far, I’ve had no issues with function or accuracy with any of my Gen 3 Glocks (G19, G34). Recently, however, I’ve noticed some strange behavior when shot through a Gen 4 G34. At 50ft, the Gen 4 is grouping 2-inches high and 2-inches left. The same gun shoots POI/POA with Federal HST 124gr, Speer Gold Dot 124gr, and my friend’s light 147gr reloads. Any thoughts as to why I'm seeing a POI shift from my reloads only with the Gen 4 G34? 

This is the load I’m using:
X-treme copper plated, 9mm, 124gr RN
4gr Titegroup
1.150" OAL
Crimp is about .379" - .378" DIA
CCI Small Pistol Primers
Primarily Federal and Blazer brass
Loaded on a Dillon 650

Velocity is around 1131fps

I've verified this behavior a few times and have even had a couple other people shoot the gun and experience the same POI shift.

[jcc7x7]

Just one of those things

Might try another bullet, get some sample packs and hopefully one hits same poi

[Brucenterry]

You may try swapping barrels to see if it follows the gun.  Only other difference is the recoil spring.  I have a gen4 that does this.  Had several people shoot it and tried several brands of ammo but still the same results (high left).  Swapped barrels and it improved so I bought a KKM barrel but still not as good as my gen3's. 

[MemphisMechanic]

Change your OAL or try +\- 0.2 grains in charge weight, or change powders or bullets entirely, and see what happens.

Some bullets or bullet & powder combinations don't like certain guns. Just the way it is.

[Sarge]

16 minutes ago, MemphisMechanic said:

Change your OAL or try +\- 0.2 grains in charge weight, or change powders or bullets entirely, and see what happens.

Some bullets or bullet & powder combinations don't like certain guns. Just the way it is.

Absolutely! I learned by accident that Groups varied from dead on, to high right, low left etc by changing oal, charge weight, bullet brand etc

[dillon]

Different primers can cause a shift in location of a group. Buy a few boxes of different brands of primers, load 10 rounds, and shoot them on different targets. See which one groups closer to point of aim.

[a matt]

3n38 shoots like a champ but AutoComp & HS-6 are all over the place. Then the HS-6 & AutoComp shoot great outta guns 2 & 3 but 3n38 is a joke. You can't hit cardboard at 25 yards. Gun 4 3n38 only. Another "one of those things". Cheers....

i believe I'm gong to try some Acurate #7. But only because VV is stupid expensive but it is great powder after you see the finance officer to get enough for a year, lmao.