How Many Tune Rifles with Action Screw Torque

[Trickymissfit]

Interesting topic. I hope to learn something here. I always figured if it was bedded properly it should not matter if it is 50 or 65 in lbs.

Jeff gun)

a 1/4-28 screw is way over tightened (past it yield point) with anything much more than 10 ft. lb. Normally 50 to 60 in. lb. is about the max. Buy a can of Neversieze with Nickel (Donot use Loctite Antisieze!!), and lightly coat the threads with a small paint brush. Then torque the screws down to about 40 In. Lb. for starters. That 40 in. lb. is actually over tightening them, but it's a start. You probably will be able to get by with 30 in. lb. of torque as you can cut the torque value in half when using Neversieze compound. Another thing todo is to replace the screws after retorquing them a few times due to stretch (they will be grade five if they are black, and not as good if they are stainless steel). The best screws are from Premier, Karr, and Allen. Unbrako are right behind these; with the first two being the best you can buy.
gary

 

[shortgrass]

I have a problem with accuracy. I found that the action screws were a little loose. I tightened them to 60 ibs. Does anyone know if this would fix the problem? I would go to the range but I dont have time right now but if someone knows it would help.

That's kinda' the point, Duke,, there are no set rules. I think if you can effect accuracy with screw torque you've got bedding problems. I'll , also, point out that there is a difference in torque recommendations between lubricated and non-lubricated threads.

 

[J E Custom]

Very interesting topic! I have seen rifles that were finicky about torque but I always felt it was a bedding problem. I believe if an action is properly bedded, there is a much larger window of acceptable torque and only enough torque is needed to keep things from moving with additional torque not affecting anything one way or the other. I will be very interested,however; in what others have found.......Rich

+1

I have found that if the pillars and bedding are correctly installed it rarely makes any difference.

I use 55 to 65 inch pounds on all fully bedded and pillared actions (This includes the stocks
with integral bedding blocks).

"But" on factory stocks, be it wood,plastic or synthetic if they have non pillars or bedding
It Does make a difference. Start at 35 inch pounds (Minimum) and work up 5 Inch pounds
at a time and there will be a sweet spot if you have good consistant loads and a reasonable
barrel.

The problem with this process is that the group size and POI can change over time and
condition changes.

It is always best to do a full pillar bed if consistant performance is desired.

Just my experience.

J E CUSTOM

 

[Trickymissfit]

remember the max torque value for a stainless steel screw is less than half of what a stanadar black steel cap screw is. The same can be said for tensil strength and shear strength as well. It's also a very good idea to at least put a drop of oil on the threads before threading them in the holes
gary

 

[BigSkyGP]

Lubing threads, oil or anti-sieze, increases torque applied by 50% of indicated.
Mechanically speaking.

Max torqe on action screws for the USMC M40A3 (Rem 700SA) over glass bedding no pillars was 40inlbs dry. Any thing more would crack the bedding compound. Using McMillan fiberglass stock.

Yes, Beam and Dial Torqe wrenches are more acurate than break-over/clicking style.

Everything flexes, even hard stuff, glass, diamond, etc.

 

[Trickymissfit]

Lubing threads, oil or anti-sieze, increases torque applied by 50% of indicated.
Mechanically speaking.

Max torqe on action screws for the USMC M40A3 (Rem 700SA) over glass bedding no pillars was 40inlbs dry. Any thing more would crack the bedding compound. Using McMillan fiberglass stock.

Yes, Beam and Dial Torqe wrenches are more acurate than break-over/clicking style.

Everything flexes, even hard stuff, glass, diamond, etc.

I think you missunderstood my comment. When coating threads with Neversieze you can (and should) reduce the actual applied torque to the threads by 50%. I've personally found it to be closer to 30% due to thread quality, and contact values. If the thread was aircraft quality and ground, then yes I'd reduce the torque value by 50%. This and the fact that most all bolts use a rolled thread instead of a cut thread gives me the numbers. Virtually all threads with the exception of a ground thread with a proper helix angle will not hold 100% of their torque value. It's the nature of the beast, and also is why Loctite is in business. You torque a bolt down to 50 ft. lb. and check it a year later and it's maybe 40 ft. lb. Plus bolt quality varies all over the place unless you use a premium quality bolt. In high stress areas many folks are now useing a dial indicator to measure thread stretch rather than applied torque (normally only seen the a nut & bolt). Also 95% of the bolt manufaturers will tell you it's almost a waste of time to torque a bolt to a certain spec without a hardened washer under the head.

The reason the glass bedding is cracking under compression is not due to torque, but the reciever acting as a wedge trying to split the stock. There are compounds that will not split under a hundred pounds of torque, and are readilly accessable to the masses. Yet whoever is putting them together is still stuck in the 1970's. This also kinda shows a flaw in the stock design as well. It's a well known problem with all round actions, and pillar bedding stops this.
gary

 

[BigSkyGP]

I think you missunderstood my comment. When coating threads with Neversieze you can (and should) reduce the actual applied torque to the threads by 50%. I've personally found it to be closer to 30% due to thread quality, and contact values. If the thread was aircraft quality and ground, then yes I'd reduce the torque value by 50%. This and the fact that most all bolts use a rolled thread instead of a cut thread gives me the numbers. Virtually all threads with the exception of a ground thread with a proper helix angle will not hold 100% of their torque value. It's the nature of the beast, and also is why Loctite is in business. You torque a bolt down to 50 ft. lb. and check it a year later and it's maybe 40 ft. lb. Plus bolt quality varies all over the place unless you use a premium quality bolt. In high stress areas many folks are now useing a dial indicator to measure thread stretch rather than applied torque (normally only seen the a nut & bolt). Also 95% of the bolt manufaturers will tell you it's almost a waste of time to torque a bolt to a certain spec without a hardened washer under the head.

> I was seconding your opinion. Yes, you have also enlightend me as to types of bolt quality and their influence. You have helped me to understand my own theories better. Thanks.

The reason the glass bedding is cracking under compression is not due to torque, but the reciever acting as a wedge trying to split the stock. There are compounds that will not split under a hundred pounds of torque, and are readilly accessable to the masses. Yet whoever is putting them together is still stuck in the 1970's. This also kinda shows a flaw in the stock design as well. It's a well known problem with all round actions, and pillar bedding stops this.
gary

>I thought the cracking compoung had something to do with the round action. Thanks for confirming this, and the tip with pillar bedding. I'm sure this will help others, as well.

 

[J E Custom]

>I thought the cracking compoung had something to do with the round action. Thanks for confirming this, and the tip with pillar bedding. I'm sure this will help others, as well.

I have to say this is a new one to me.

I have been bedding and fixing rifles for over 50 years and I have never seen or heard
of a stock being split by the shape of the action.

The only time I have seen the results of over torquing is on the Sendero's with the bedding
system that uses the upper part of the bedding block to engage the action (Like a V block)
And if over tightened it will spring open and stay there instead of working like it is supposed
to. The only fix is to do a full bedding job.

If an action, Any action splits the stock IT WAS NOT INLETTED CORRECTLY or an Impact wench
with lots of torque for installing lug nuts was used.

J E CUSTOM

 

[Trickymissfit]

I have to say this is a new one to me.

I have been bedding and fixing rifles for over 50 years and I have never seen or heard
of a stock being split by the shape of the action.

The only time I have seen the results of over torquing is on the Sendero's with the bedding
system that uses the upper part of the bedding block to engage the action (Like a V block)
And if over tightened it will spring open and stay there instead of working like it is supposed
to. The only fix is to do a full bedding job.

If an action, Any action splits the stock IT WAS NOT INLETTED CORRECTLY or an Impact wench
with lots of torque for installing lug nuts was used.

J E CUSTOM

* find out what the shrink factor is on the bedding compound (all of them shrink as it's the nature of the beast

* the original thought was about the bedding compound cracking. Most compounds are ridgid, and it only takes a few thousands to crack the compound

* why are benchrest actions glued in place? Because everything is constantly moving! The only way they can take them apart is by freezing the gun (most epoxy compounds are not friendly to extreme cold)

gary

 

[shortgrass]

* find out what the shrink factor is on the bedding compound (all of them shrink as it's the nature of the beast

* the original thought was about the bedding compound cracking. Most compounds are ridgid, and it only takes a few thousands to crack the compound

* why are benchrest actions glued in place? Because everything is constantly moving! The only way they can take them apart is by freezing the gun (most epoxy compounds are not friendly to extreme cold)

gary

That didn't answer a thing about "split", TM. I'm with JE on this. In theory, ya, maybe. More likely it's "crush" from over torque of the action screws on to material that isn't properly supported. Ya , epoxy shrinks, anybody thats done any serious bedding knows that, but what's that shrinkage got to do with "split". I think "crush" is the word here.

 

[Pdvdh]

I'm glad this Thread was revived after an 8-month coma.

Thanks for the additional comments and information. What J E Custom says makes sense, and is what I suspected - but just wasn't overly confident. shortgrass, Trickymissfit and others - appreciate your recent thoughts & feedback.

 

[Trickymissfit]

That didn't answer a thing about "split", TM. I'm with JE on this. In theory, ya, maybe. More likely it's "crush" from over torque of the action screws on to material that isn't properly supported. Ya , epoxy shrinks, anybody thats done any serious bedding knows that, but what's that shrinkage got to do with "split". I think "crush" is the word here.

No your right about the crush, but it's what the crush does. It speads everything as it moves towards the bottom of the stock. A flat bottomed reciever never seems to have this problem as everything is contained (assuming your using a bedding block)

Shrinkage is a varible that no one wants to address without adding a few dollars to the bedding job. Some epoxys shrink several thousandths, and some shrink very little (Moglice and ATF are the very best). Ever triangulate .001" in 30" out to 100 yards? That's why actions are glued in for benchrest shooting
gary

 

[shortgrass]

TM, I can almost guarantee you can crush a McMillian stock, that doesn't have pillars, with a flat bottomed Winchester, too. Triangulate away, your jekin' the wings off of nats here. No matter how tight the screw torque is or isn't there needs to be solid foundation under whatever is used for bedding material. Put away that impact wrench, it's got no place in gun work.

 

[damoncali]

Hi all, just found this forum, and saw this old thread. I wrote an article on the topic a few weeks ago that might be of interest:

Action Screw Torque

In a nutshell, my take is that if you're "tuning" your rifle with action screws, you may have a bedding problem - the mating surfaces are poor, pillars aren't used, or the recoil lug isn't making good contact. In any case, enjoy the article. I'd love to hear your feedback.

Regards - Damon