Help with vertical stringing

[flyfisherman246]

I spun up a bartlein barrel blank chambered in .223 wylde. I have it set in an aero m4e1 enhanced upper/handguard set up. I have the barrel nut torqued to 60 ft lbs.

I have tried different scopes, lots of different ammo, both factory and handloads, all kinds of powder and bullet weights.

It's so damn inconsistent, it will put a couple in one tiny hole and then starts walking vertically. (Usually starts walking down)

What causes this? I figured the aero enhanced upper was a good system for solid lockup. It seams like something is mechanically wrong here. I have tore the whole thing apart and put it back together multiple times. Any ideas?

 

[Triple D]

My guess would be that you’re loading the bipod more during the group and that’s translating to a minor shift in the barrel POA, which gives you the stringing POI.

 

[TheGerman]

Vertical stringing at shorter ranges is 99% of the time due to rear bag manipulation (or letting is slack) during shooting or a sympathetic shoulder.

 

[flyfisherman246]

So let's pretend I have and shoot many other ar15/10 rifles and I'm very happy with how they shoot. So I don't think it's a technique thing. As far as bipod loading goes, I can honestly see that and that's why I went with the aero enhanced upper. I figured that would take care of that issue. And I've also been pretty careful about consistent loading of the bipod while doing this testing. Has anyone run into issues with aero enhanced uppers for accuracy or lack of consistency?

 

[flyfisherman246]

So today I put that barrel in a thermo fit upper receiver and an slr handguard. The results were much better and there was no more vertical stringing. I put that barrel back in aero enhanced upper and it is doing some more stringing. (Not as bad this time). I torqued the barrel nut to 45 ft lbs instead of the 60 last time. But it seams like the barrel extension is wiggling around in there enough to cause stringing. With the enhanced uppers barrel nut being internal instead of external, I would think the more you tighten the more it would act like a wedge and open up the inside diameter of the receiver. Has anybody had any luck with the aero enhanced upper? What did you torque it to?