Accuracy International AT-X

The sweet spot seemed to be 55 inch lb and some guys running up to 65 inch on the AXMC platform

I run 55 on mine
Okie, going to be a 6BR, 26" 1.125 straight, 7.5 with Cortina V2 and Area 419 HFM. May just go right to 55. I will be using the identical reloading equipment, components and recipe as the builder uses the same to great success on his rifle.
 
Manual states 49 inch pounds on the barrel lock screw. Getting ready to change a barrel, anyone have issues with loosening or barrel exhibiting better accuracy in the higher ranges, 55-65?
I use this technique. Was doing 60, but some engineer-type said 55 for bolt stretch reasons…I’d attempt to explain further but I’d just use all of the wrong words lol.

I think logically his technique below makes sense, but I can’t back anything up with tests.

 
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I’ve had the best luck on my old AT and new AT-XC with 65 in/lbs. I also have flats on all my barrels so I tighten them some with a crescent wrench before torquing the quick lock screw. I’ve found this makes everything very consistent and seem to see slightly better groups.
 
The stock 49 or whatever the nearest fixit stick works for me. My first shot is usually 0.2 mil low and I'm not sure if that's the barrel or suppressor seating or barrel fouling or all the above. My RTZ is consistent so I have seen a need to try any different torque settings.
 
Keep in mind one issue particularly with the bonded AT/AX was bonding agent getting in between the clamp area on the quickloc. Which contributed to people having issues with 49 inch lbs not being enough and inconsistent

The AT/AX/AXMC are all bonded unlike the ATX
 
Does anybody know what freebore and neck diameter the 6BR factory AI barrels are reamed with?
I'd say the fb is around 120 length, as it's bout 15k longer than my 104fb barrel. The fired brass comes out 2725-273. So I'm guessing it's a 274 or slightly smaller neck. This is a 7.25tw 26in Wintac AI house brand barrel. Headspace is a bit long......virgin brass is growing 0.005-0.00055, running 29.7gr Varg with a 105 moving 2800.

Just what I've found with the one AI 6br barrel I have. I have a few other BR barrels that are chambered to go gauge plus 0025, and they're about a thou shorter in headspace VS this particular setup. Could be action headspace variation. I torque my barrel up relatively tight with a 24in crescent then torque the quick change screw to 55"/#.
 
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My impact barrel on my comp gun is a .130 freebore and .274 neck diameter, which has been great for no turn prep on lapua brass. I’ve been at 30.2 gr Varget and was hoping the barrel specs were roughly comparable on the factory AI. That way, I could just keep using the same ammo across both guns.
 
Quick question for all the gents in this forum. I purchased a AT-XC and I am waiting for it to show this summer. I have a small fortune in AW mags, will they work without issue in this chassis? I cannot seem to find any real answer. I am over $1500 in aw mags and would love to not have to start stacking up another form of magazine. Appreciate any insight!
 
Quick question for all the gents in this forum. I purchased a AT-XC and I am waiting for it to show this summer. I have a small fortune in AW mags, will they work without issue in this chassis? I cannot seem to find any real answer. I am over $1500 in aw mags and would love to not have to start stacking up another form of magazine. Appreciate any insight!
They should work fine @Rory_Fritz uses them in his Gen 1 AT-X with no issue and I can't imagine they've changed the design so dramatically since then that they wouldn't work.
 
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Little barrel chop.
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