AXMC Accuracy Troubleshooting

[jps24]

A few years ago, I used to tighten down the AXMC barrel clamp screw with the short end of an allen wrench until it was tight since I didn't have a torque wrench at the time. I was getting just over 1/3 MOA accuracy with 6.5 CM handloads.

Fast forward a few years to now in which the rifle has been in a safe. I now tightened the barrel clamp to manual specs of 49 inlbs. Using the same handloads, my accuracy is anywhere from 1/2 to 1 MOA.

These are the three things I changed on my rifle from a few years ago:

1. The barrel clamp tightening
2. Now using a suppressor instead of a fat bastard muzzle break.
3. I moved my scope back in the rings slightly for a more comfortable eye position.

I'm going to try and troubleshoot this tomorrow. I'm hoping the issue is resolved by the barrel clamp tightness. If not, then I will remove suppressor. If suppressor is not an issue, then I'm not really sure what's going on.

I'd like to hear anyone's input or recommendations.

Thanks.

 

[hafejd30]

Most guys are getting best results around 60 inch lbs. That’s what I ran my AXMC at in 6.5 for a short bit and it was an absolute hammer

Seems the short actions are more forgiving

I run my AT and ATX (now) at 55 inch lbs

 

[oldrifleman]

I would bet on it being the Suppressor

 

[hafejd30]

Also keep in mind it sat for a while. Are you running the same exact loads, same lot #, has the barrel been cleaned, are you out of practice

Could be several variables. I let my fclass 284 sit dirty. Took it out and it wouldn’t hold 1 moa of vertical

 

[jps24]

Also keep in mind it sat for a while. Are you running the same exact loads, same lot #, has the barrel been cleaned, are you out of practice

Could be several variables. I let my fclass 284 sit dirty. Took it out and it wouldn’t hold 1 moa of vertical

Exact same loads, the rounds sat in a box from the last time I shot a few years ago. I cleaned the barrel, chamber and bolt once it came out of the safe.

 

[hafejd30]

Exact same loads, the rounds sat in a box from the last time I shot a few years ago. I cleaned the barrel, chamber and bolt once it came out of the safe.

Clean barrel can definitely do it. So can rounds sitting for a while. Some guys in bench and fclass load right before a match or leave the OAL long and seat the bullet right before the match.

If you’ve ever pulled reloaded bullets you’ll see the grip change over time.

Try torquing to 60 inch lbs. Then fresh ammo. Bet it settles back

 

[jps24]

Also forgot to say another change between the years:

I swapped out the standard handguard for the Victor Company AX HR1 handguard.

 

[Hawk in WY]

You should retest your load. Powder burn rates can vary by as much as 10% from lot to lot.

 

[JohnDeereGuy1996]

Take the suppressor off and try again. Barrel harmonics are a weird thing.

 

[Bacarrat]

Most guys are getting best results around 60 inch lbs. That’s what I ran my AXMC at in 6.5 for a short bit and it was an absolute hammer

Seems the short actions are more forgiving

I run my AT and ATX (now) at 55 inch lbs

Had a fellow member on here had his groups effected by this. Torqued the barrel down to 60in lbs and the barrel started shooting easy .5 MOA groups. Before it was all over the place and would be lucky to shoot 2MOA.

 

[hafejd30]

Had a fellow member on here had his groups effected by this. Torqued the barrel down to 60in lbs and the barrel started shooting easy .5 MOA groups. Before it was all over the place and would be lucky to shoot 2MOA.

Seems 55-65 is the sweet spot according to others who have tested this here. Seen as high at 80 but not sure I’d go that high.

 

[jps24]

Today I adjusted the torque to as high as 65. My group was still approximately 1 MOA. But when I backed it off to about 55 my group decreased to just under .5 MOA.

I marked the barrel clamp screw with a paint marker to ensure I tighten it to the same spot in the future.

Thanks for everyone's advice.

 

[Jrb572]

The AXMC maintenance manual says 5.5nm which is roughly 50 inch pounds. I always set mine at 55 inch pounds.