Accuracy International - Alternative Barrel Clamp Torque Specs?

HKSniper11B

HKSniper11B

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#1
Was talking to a friend who has many more years experience than I with the Accuracy International AT308, and he and his department run Hornady TAP ELD Precision 168gr exclusively as a SWAT Sniper. While I've had a hard time getting this ammo to group tightly despite its superior ballistics on paper, he and his guys are getting notably better accuracy and precision with it, from the Lothar-Walther 1:12 20/24 inch barrel. The difference is, I'm torqued to 49 inch/lbs, while he and his guys are at 55 inch lbs, so 6 in/lbs over factory spec.

Is this common? Have folks here played with different torque specs for the barrel clamp screw? And, what grease if any are you guys putting on your barrel threads before screwing and clamping it in?
 
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#5
sidetoss20 said:
There has been some documentation of this here, some guys have found that they have better return to zero when spinning a barrel back on using different torque values. Not unheard of
Click to expand...
www.snipershide.com

AI AT308 Barrel Change

I purchased a used AI AT308 on the exchange here that included a 6.5 Creedmor barrel. I can’t find the exact specifications in the owner’s manual. In searching the forums, it seems people quote the retaining screw for the muzzle brake in saying it’s a 4mm hex key and to tighten to 36in/lbs. I...
www.snipershide.com www.snipershide.com

This is the only other thread I found so far. Still searching for older threads on the topic.
 
#7
HKSniper11B said:
www.snipershide.com

AI AT308 Barrel Change

I purchased a used AI AT308 on the exchange here that included a 6.5 Creedmor barrel. I can’t find the exact specifications in the owner’s manual. In searching the forums, it seems people quote the retaining screw for the muzzle brake in saying it’s a 4mm hex key and to tighten to 36in/lbs. I...
www.snipershide.com www.snipershide.com

This is the only other thread I found so far. Still searching for older threads on the topic.
Click to expand...

I think this is @Huskydriver ’s favorite topic
 
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#10
HKSniper11B said:
I read this thread as well, although it doesn't share much other than stating the factory spec of 49 inch/lbs.
Click to expand...
You ll find that what works for one gun/barrel/ammo combination might not work for another.

Which Grease/anti seize is being used is not the issue.

I would suggest you do your own testing with different tq values and create your own superstitions, and then stick to them.

Keep the shoulders/face clean and be as repeatable as possible everywhere you can.
 
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#11
I do this, only at 60in/lbs.

www.snipershide.com

Going MC: Cadex Kraken or AI AXSR?

Hello all. I've owned an AI AWM in .300 WM since the early 2000s. I've decided it's time to sell it and move to a multi caliber platform. Long range opportunities are rare around here so having a .308 for regular use that can occasionally be converted to a long distance chambering makes sense...
www.snipershide.com www.snipershide.com
 
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#14
I did a bunch of searching a while back and ended up on 55 inch lbs on mine. There were threads of people having barrels loosen at 49 or be inconsistent. The last bit seemed to help

samb300 had a theory that epoxy they use to glue the action to the chassis was getting inside the “ears” of the clamp and affecting torque

Mine I snug with a small barrel wrench I have on the flats or a small crescent wrench. Do it’s just past hand tight where’s it’s still easy to loosen with the wrench. Then torque to 55 no lube

Here’s an AXMC thread with some AT/AX info
www.snipershide.com

AXMC barrel torque

I haven't used the switching function on my AXMC and wanted to confirm what the torque was on the bolt. I think the manual says 49 in-lb. But I remember a few people, including @lowlight , mentioning they use higher (maybe 55?) and that the lower factory spec didn't show as much repeatability...
www.snipershide.com www.snipershide.com
 
#16
AXSR w/ all factory AI barrels:

I put a small bit of anti seize on the barrel threads, hand tight, then a lil “Hmmf” with a wrench. Pop on a 55in/lb fix it stick limiter and get to work.

No issues with backing off, accuracy problems, or anything like that. Did the same thing at 49in/lb when I first got it but never had issues there either.

Test it for yourself and see what works.

Best of luck!
🍻
 
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#19
carbonbased said:
Yeah, afaik you’re not even supposed to remove that QC bolt due to losing a washer in-between the action and chassis (or something like that).
Click to expand...
What you should not do is torquing the bolt on without a barrel.

Bolt heads get worn/round over time and you replace em as if its any other bolt. Ive replaced some of mine a few times already.

The washer is just sitting there. You lose it just get another from mcmaster/ace ect
 
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#20
Mr. F said:
What you should not do is torquing the bolt on without a barrel.

Bolt heads get worn/round over time and you replace em as if its any other bolt. Ive replaced some of mine a few times already.

The washer is just sitting there. You lose it just get another from mcmaster/ace ect
Click to expand...
I’m definitely not torquing a bolt without a barrel installed. Who is doing that?

I suppose if the hex head is messed up, then yeah, you must replace the bolt. AI itself says to not remove that bolt, apparently due to the washer issue.
1726168641445.png


But hey, if you’ve fixed this issue yourself, more power to you.

Still not sure how that other fellow thought people were greasing the QC screw. Maybe he mixed it up with greasing the barrel tenon?
 
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#21
carbonbased said:
I’m definitely not torquing a bolt without a barrel installed. Who is doing that?

I suppose if the hex head is messed up, then yeah, you must replace the bolt. AI itself says to not remove that bolt, apparently due to the washer issue.
View attachment 8500177

But hey, if you’ve fixed this issue yourself, more power to you.

Still not sure how that other fellow thought people were greasing the QC screw. Maybe he mixed it up with greasing the barrel tenon?
Click to expand...
Probably on there so you dont lose the bolt on the field.

As far as user level maintenance i called MH years ago and they sent me a baggie of the spec metric bolts to replace and keep spares.
 
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#22
carbonbased said:
Yeah, afaik you’re not even supposed to remove that QC bolt due to losing a washer in-between the action and chassis (or something like that).
Click to expand...
I dunno what he meant about a wet torque butttt the cool thing about the non-bonded AIs is that you can tear it all down and go get a full bag of spare parts from Ace.

I like to challenge myself by taking all of the bolts out of my rifle, putting them into one bag, shake it up, and then putting it back together. The last time I did this I was almost able to get it back together without leftover bolts 😂
 
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#23
Yes, it was a misunderstanding on my end. I thought op was asking about using anti-seize grease on both The barrel threads and QC bolt. I've personally removed the QC bolt without issue, and I've tried both 49 & 55 in lbs and didn't notice a difference on my AXMC. I also raw dog it and run dry myself.
 
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#25
sidetoss20 said:
I think this is @Huskydriver ’s favorite topic
Click to expand...

So I tested it all the way up to like 80 or 90inlbs iirm...

I didn't notice groups really changing much unless at 49... Mine wasn't a fan . What I did see was if I hand torqued on my barrel with a type 2 ugga bugga and did a 55inlb or over, my rtz was dead on everytime
..


Wtf is putting antiseize on and the barrel and why lol? You are not torquing it on at hk 200ft lbs.....


anti_seize_meme_fullsize.jpg
 
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#26
carbonbased said:
I do this, only at 60in/lbs.

www.snipershide.com

Going MC: Cadex Kraken or AI AXSR?

Hello all. I've owned an AI AWM in .300 WM since the early 2000s. I've decided it's time to sell it and move to a multi caliber platform. Long range opportunities are rare around here so having a .308 for regular use that can occasionally be converted to a long distance chambering makes sense...
www.snipershide.com www.snipershide.com
Click to expand...
62 in/lbs for me
 
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#28
Sounds like a 55 in/lbs Fix-It Stick is gonna get ordered now. Glad I got more confirmation of what works and what doesn't, which is going to save me a lot of time and money testing minute torque differences.

Called Mile High today and asked about if they use any kind lithium grease or anti-seize on the barrel threads. They explicitly said no, as any and all of that can get in the H cutout at the bottom of the action receiver where that screw tightens things down around the barrel, and it's essentially impossible to properly clean in the AT308.

I've opted for a small simple drop of gun grease, same I use on my lugs, and run it with that once and only once. Will go dry moving forward should I break the barrel off again.

Still, I find it interesting that from 55-80+ in/lbs, no change. But from 49 changed up to 55, there's accuracy differences. Makes me wonder how they originally came up with 49 in the first place.
 
#29
HKSniper11B said:
Sounds like a 55 in/lbs Fix-It Stick is gonna get ordered now. Glad I got more confirmation of what works and what doesn't, which is going to save me a lot of time and money testing minute torque differences.

Called Mile High today and asked about if they use any kind lithium grease or anti-seize on the barrel threads. They explicitly said no, as any and all of that can get in the H cutout at the bottom of the action receiver where that screw tightens things down around the barrel, and it's essentially impossible to properly clean in the AT308.

I've opted for a small simple drop of gun grease, same I use on my lugs, and run it with that once and only once. Will go dry moving forward should I break the barrel off again.

Still, I find it interesting that from 55-80+ in/lbs, no change. But from 49 changed up to 55, there's accuracy differences. Makes me wonder how they originally came up with 49 in the first place.
Click to expand...

So I'm saying 49 then go to 55 but I don't pay to calibrate my wrench.... It very well could be 45 and 51... Regardless you gotta test it yourself with the tool you have.

Ymmv
 
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#32
I use a drop of CLP, and my calibrated forearm regarding the correct amount of torque on my AT-X. If anything, I'm over 49in/lbs.

So far, I have seen no difference in group sizes between barrel swaps...but MAYBE I see .2 - .3 shift when I pull the barrel, clean, and reinstall. It takes two shots to re-zero and then I'm back to normal. I don't consider that a handicap.
 
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#33
60inlbs for the SA, 70 for magnum.

It’s also important to make sure the action face and barrel shoulder and completely free of debris. Seating the barrel a little more than snug with the muzzle straight up using a wrench on the flats is also beneficial.

This is the process I always used for best accuracy and zero POI shift.
 
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#34
I remember @samb300 had a theory about why some guns would shoot fine at 49 in lbs and others wouldn't. He suspected that epoxy would get into the QC area, essentially gluing the lugs to the chassis (requiring more torque to move them). Now that the AXSR (not bonded) has been out for longer perhaps he has a better understanding if this theory is correct.

I also never used anti-seize or lube, because I figured it would attract debris.

www.snipershide.com

AXMC barrel torque

I haven't used the switching function on my AXMC and wanted to confirm what the torque was on the bolt. I think the manual says 49 in-lb. But I remember a few people, including @lowlight , mentioning they use higher (maybe 55?) and that the lower factory spec didn't show as much repeatability...
www.snipershide.com www.snipershide.com
 
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#35
Bkultra said:
I remember @samb300 had a theory about why some guns would shoot fine at 49 in lbs and others wouldn't. He suspected that epoxy would get into the QC area, essentially gluing the lugs to the chassis (requiring more torque to move them). Now that the AXSR has been out for longer perhaps he has a butter understanding if this theory is correct.

I also never used anti-seize or lube, because I figured it would attract debris.

www.snipershide.com

AXMC barrel torque

I haven't used the switching function on my AXMC and wanted to confirm what the torque was on the bolt. I think the manual says 49 in-lb. But I remember a few people, including @lowlight , mentioning they use higher (maybe 55?) and that the lower factory spec didn't show as much repeatability...
www.snipershide.com www.snipershide.com
Click to expand...
For an AT308, this would be an interesting theory as to why.
 
#36
Bkultra said:
I remember @samb300 had a theory about why some guns would shoot fine at 49 in lbs and others wouldn't. He suspected that epoxy would get into the QC area, essentially gluing the lugs to the chassis (requiring more torque to move them). Now that the AXSR (not bonded) has been out for longer perhaps he has a better understanding if this theory is correct.

I also never used anti-seize or lube, because I figured it would attract debris.

www.snipershide.com

AXMC barrel torque

I haven't used the switching function on my AXMC and wanted to confirm what the torque was on the bolt. I think the manual says 49 in-lb. But I remember a few people, including @lowlight , mentioning they use higher (maybe 55?) and that the lower factory spec didn't show as much repeatability...
www.snipershide.com www.snipershide.com
Click to expand...
I've seen some pictures of de-bonded short action rifles that had epoxy on the wing(s) of the barrel tenon clamp. My theory is that if one of those wings were bonded to the chassis and essentially immovable, the torque needed would increase since only one half would be moving to clamp on the tenon.

With bonded rifles it's not really feasible to de-bond it just to see if that area has too much epoxy lol

If certain atxs or axsrs shot better with higher torque then that would be something else.

FYI depending on the grade of the bolt, an M5x.8 would exceed max recommended torque around 55 in-lb so I think going to like 70 in-lb would just be stretching the bolt and not even torquing it beyond 55 in-lb
 
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#37
M8541Reaper said:
I dunno what he meant about a wet torque butttt the cool thing about the non-bonded AIs is that you can tear it all down and go get a full bag of spare parts from Ace.

I like to challenge myself by taking all of the bolts out of my rifle, putting them into one bag, shake it up, and then putting it back together. The last time I did this I was almost able to get it back together without leftover bolts 😂
Click to expand...
That is called autism
 
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#40
hafejd30 said:
I snug with a small barrel wrench I have on the flats or a small crescent wrench. Do it’s just past hand tight where’s it’s still easy to loosen with the wrench. Then torque to 55 no lube
Click to expand...
Yes I do this with a small adjustable on barrel flats or tbac brake. Then 68 pounds
 
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