OFFICIAL Accuracy International Cold Bore / Return to Zero Thread

[RedBreast21]

This is a data collection thread. Please post labeled (cold bore/pre or post barrel install) targets if you can. There's no real goal here, just trying to see what we might learn from people posting one of or both of two different things: 1) How does your cold bore differ from follow up shots? 2) How well does your rifle return to zero after the barrel has been removed? In replying to this thread, please answer the following questions

1) Model Rifle (AXSA, AXSR, AXMC, AX-T, AX-TC, etc)?
2) Caliber (or calibers)?
3) Barrel Length?
3) Bullet and grain weight used?
4) What was the Muzzle Velocity?
5) Suppressed or not?
6) For pre/post barrel removal please indicate method of tightening bolt (i.e. Fix-it sticks, expensive torque wrench, hand tighten, etc)
7) For pre/post barrel removal, please indicate whether barrel was allowed to cool between shots.

 

[redneckbmxer24]

Across multiple AXSA’s, a AT, a AXMC, and a PSR none of mine ever displayed any sort of a cold bore shift and none had a shift removing and reinstalling the barrel. I shot suppressed and unsuppressed and a bunch of chamberings. The only time POI shifter was a different barrel going on but it was consistent so I always just recorded the shift for various barrels and adjusted accordingly.

If I just spun a barrel on and torque the screw they would take a couple shots to walk in, but properly installed I could put rounds through the same hole pulling the barrels in between with any of them. The key is making sure the shoulder surfaces are 100% free of debris before seating the barrel and installing the barrel with the muzzle straight up and seat it snug with a wrench on the flats using a snapping motion. Then torque your quick lock bolt.

 

[RomanM1A]

I'd like to understand how torque impacts return to zero in the AX. Does anyone have any experience testing?

 

[jbell]

Across multiple AXSA’s, a AT, a AXMC, and a PSR none of mine ever displayed any sort of a cold bore shift and none had a shift removing and reinstalling the barrel. I shot suppressed and unsuppressed and a bunch of chamberings. The only time POI shifter was a different barrel going on but it was consistent so I always just recorded the shift for various barrels and adjusted accordingly.

If I just spun a barrel on and torque the screw they would take a couple shots to walk in, but properly installed I could put rounds through the same hole pulling the barrels in between with any of them. The key is making sure the shoulder surfaces are 100% free of debris before seating the barrel and installing the barrel with the muzzle straight up and seat it snug with a wrench on the flats using a snapping motion. Then torque your quick lock bolt.

Agreed

Over 2 AWs, and 2 or 3 ATs (I can’t remember for sure), one being deboned and in an MPA chassis, and I am not sure how many barrels I never experienced a POI shift with cold clean bore, or cold dirty bore. Every rifle and every barrel I tested POI / Zero shift / drift / need to settle in, there was none as long as you pay attention to installing the barrel.

 

[jbell]

I'd like to understand how torque impacts return to zero in the AX. Does anyone have any experience testing?

I never tested different torque specs:

AIAW: 100 lbft
AIAT: hand tight and 49 lbin on the screw.

 

[RomanM1A]

I never tested different torque specs:

AIAW: 100 lbft
AIAT: hand tight and 49 lbin on the screw.

Really what I meant was, considering each torque tool has a % +/- variance. Is one more consistent others? Fixit vs RealAvid or Wheeler, etc.

 

[RedBreast21]

When I had my MRAD, I spent big money on a Seekonk Torque Wrench (I still have it if anyone is interested - used like 10 times). It is large, heavy and expensive. I have had very good results with my FixIt Stix adapter, but I actually have found that the amount of torque might not be that important. I'm not saying that I have forgotten to torque down a barrel before, but if I had, it might be the case that the gun still performed reasonably well, but the POI may have shifted.

 

[B4forever]

16” AT-LE in .308…zero shift in cold bore for both 168gr Federal Tactical Tru and bonded. Both ammunition types have the exact same POI at 100y as well. Lucky me.

 

[jbell]

Really what I meant was, considering each torque tool has a % +/- variance. Is one more consistent others? Fixit vs RealAvid or Wheeler, etc.

Probably not as long as you are using a reputable brand torque wrench / device. Most claim accuracy within 2% - 3% I think but 5% of 49 lbin is only 2.5 lbin & of course 5 lbft on 100 lbft. That isn’t going to matter. I really like my Borka and Fix It tools.

 

[WillHugh]

Gen 1 AT-X with 24" 6.5 CM barrel. No cold bore shift. Also returns perfectly to zero when removed and reinstalled. I use the carefully calibrated "by feel" technique when tightening the screw.

Joking aside, I do turn the screw until it starts to tension, and then clock it to the same point using the allen wrench handle. Seems to work well enough, and probably just indicates that exact torque isn't overly important.

 

[FUNCTIONAL]

AIAT and tested it on my previous AX.

No CB shift outside normal group size to either.

Shot a group uninstalling/reinstalling the barrel after every shot and it was all the same as any other group.

I just screw the barrel in, give it a good snap the final 1/4 turn and torque it to 55 in/lb with a fixed stick. I felt I needed more to keep the consistency over the 49. I don't recall what test I did to find that out. Was way back in 2016ish with my AX and I just keep doing it.