Acrion screw torque matters

[hound53]

saw a article the other day on how action screw torques can effect your groups

http://www.accurateshooter.com/technical-articles/savage-action-screw-torque-tuning/

So I did a little experiment today on my 110 action based .204. These were shot at 200 yards using 32 gr Sierra blitzkings and RL10 powder .020 off the lands. Wind was about 5 mph from the 9 oclock position and these pics need to be rotated clockwise 45 degrees (the www. targets logo at the bottom)

http://img715.imageshack.us/img715/4553/dsc00261wt.th.jpg (http://imageshack.us/photo/my-images/715/dsc00261wt.jpg/)
http://img560.imageshack.us/img560/9436/dsc00260b.th.jpg (http://imageshack.us/photo/my-images/560/dsc00260b.jpg/)

as you can see at 30 inch lbs on the front and 5 on the rear I had a long horizontal string, increasing to 10 inch pounds it went vertical and at 15 began to tighten up then at 20 I shot the 7 rounds I had left and they were all over. Next week I am going to fine tune it a bit more

[stangfish]

Good stuff. Post more as you go!

[243LPR]

Was the barrel allowed to cool completely between groups?

[Dennis]

Question: Why doesn't the custom actions requier this procedure? Bat, Stiller, Bernard, etc.

[hound53]

Was the barrel allowed to cool completely between groups?


yes, between groups I walked to the target, looked at it and walked back then shot the next group. Figure 10 - 15 minutes between walking and head scratching




Question: Why doesn't the custom actions requier this procedure? Bat, Stiller, Bernard, etc.


I don't know if it would benefit someone with a high dollar action or not. Those groups are shot from the left over 32 grainer's I was using for load testing, they did not shoot worth a darn and only gave me .375 MOA at 100. Next week I am going to fine tune with the 39's which shot a little better.

I first learned of this technique from a prone rimfire shooter who still holds several national records and was a contender for the Olympic team. He showed me how to tune my CZ 22's to bring my groups together. He shot a Anshutz match target rifle that looked like something out of a science fiction movie. He carried a torque screwdriver in his toolbox and would adjust his action screws according to the temperature and a chart he had in his range book.

I have been using the technique on my CZ's since then but never thought to apply it to my Savage until I read this article, having heard on the internet that unless you had a accustock, action screw torque did not matter. Obviously it does.

[MaDa]

Question: Why doesn't the custom actions requier this procedure? Bat, Stiller, Bernard, etc.

I think it would still have an effect. Maybe less or more. ( so long as not at hand tight/loose)


Also, can anyone. Clarify if pillar bedded stocks require a proper torque spec also?
(the head on the bolt would then be against the pillar that is bedded into the stock correct? Or no? Would therefore not be as specifIc a torque spec since your tightening against metal only, not synthetic/fiberglass or wood?)

Thank you!

[hound53]

Question: Why doesn't the custom actions requier this procedure? Bat, Stiller, Bernard, etc.

I think it would still have an effect. Maybe less or more. ( so long as not at hand tight/loose)


Also, can anyone. Clarify if pillar bedded stocks require a proper torque spec also?
(the head on the bolt would then be against the pillar that is bedded into the stock correct? Or no? Would therefore not be as specifIc a torque spec since your tightening against metal only, not synthetic/fiberglass or wood?)

Thank you!


the action I tested it on is in a Chaote SA stock which has a full aluminum bed. Oh and I don't think there is anything such as a proper torque, each rifle is going to have it's own sweet spot. I would wager that I could take another rifle with the action, barrel and stock exactly the same and they would be a bit different than this one. Just something fun to play with to try and get another .1 off the groups, still have to play with distance off the lands also. What I am really looking forward to trying this on is my model 12 action with the new 260 barrel.

[kelbro]

I tried the same experiment on a couple of two-screw actions that were pillared and fully floated. Saw no difference in point of impact relative to any torques over 30 lb/in. Subsequent action bedding (tang left floating) had no effect on these two rigs.

[1jonzmith]

I tried the same experiment on a couple of two-screw actions that were pillared and fully floated. Saw no difference in point of impact relative to any torques over 30 lb/in. Subsequent action bedding (tang left floating) had no effect on these two rigs.


I have read tons of commentary and anecdotal reports about action screw torque having a BIG affect on group size over the years. Way way to much "evidence" for any sane person to disregard the topic. What has always bothered me is that NOBODY has ever offered an explanation for just WHY this is true. I take a lot of things on faith and do stuff "just because" but almost all of that relates to dealing with women. Being confused isn't a state I seek, neither. I am certain there are explanations out there that I have never heard and I want to.

In an unbedded or pillar'd action I can easily see where the action would flex and jump around. The case for those accurizing projects was made to me long ago. To my logic, bedding the action should have been sufficient to immobilize the action and establish the "union" of the action/stock and pilars should be insufficient due to the reduced area of contact and the resulting inevitable increase in flex. BUT, I am wrong, based on tons of findings. Does anyone understand why?

In my Swede's, the rear tang screw needs to be tight to prevent the action from moving around under recoil but in them that screw is one of the two action screws. What is the theory that the rear tang in a Savage MUST float?

I can easily accept that having action screws loose will yield erratic groups. After tightening in increments the groups contract and that seems logical. Why would making the bond between the action and stock tighter ruin the groups?

I can't be the only one that doesn't understand this or wants to.

Help?

John

[bsekf]

Dennis,

The high dollar actions are usually glued in. That would stop some of the flex.

Someplace I saw a slow motion video of an action as it was fired. SCARY to think your face is just inches away. Wish sombody would find that video. Bet if there was one of an Encore or Contender there would be a bunch for sale.

Bill

[hound53]

I tried the same experiment on a couple of two-screw actions that were pillared and fully floated. Saw no difference in point of impact relative to any torques over 30 lb/in. Subsequent action bedding (tang left floating) had no effect on these two rigs.

bold and underline added

no where in the article does it suggest that you torque the screws to over 30 lb/in. I found my best groups on my experiment were at 30 front 15 rear

[kelbro]

I tried the same experiment on a couple of two-screw actions that were pillared and fully floated. Saw no difference in point of impact relative to any torques over 30 lb/in. Subsequent action bedding (tang left floating) had no effect on these two rigs.

bold and underline added

no where in the article does it suggest that you torque the screws to over 30 lb/in. I found my best groups on my experiment were at 30 front 15 rear


I read the article after I posted.

My post was not to dispute the article or the OPs observations. Just sharing my own experiences.

It was interesting to see that we agreed on the 30 number. That also happened to be the sweet spot on my Ruger 10/22 so I was able to keep my torque driver at the same setting :)

[82boy]

I tried the same experiment on a couple of two-screw actions that were pillared and fully floated. Saw no difference in point of impact relative to any torques over 30 lb/in. Subsequent action bedding (tang left floating) had no effect on these two rigs.


You came up with the same answer that I did. If torquing action screws makes a differece then there is a bedding problem.



The high dollar actions are usually glued in. That would stop some of the flex.

They are usulay glued in but not always, glueing is a cheap alternitive to bedding. This is mostly done on point blank benchrest guns, (No all, just some.) most long range guns are not glued. Top gun smiths will glue an action mostly because they are asked to do so, but most agree that a properly bedded action is just as good if not better than a glued action. Glue is also used to save weight, when dealing with a 10.5 lbs gun a few oz makes a hugh difference. The custom actions that are pillar bedded dont need the actions screws torqued because they are properly bedded.

[rdfrench]

I was under the impression that the screws needed to be torqued from 50 to 65 inch pounds. I know HS recommends 65, and I'm thinking Bell & Carlson says 50. I have the B&C Medalist sporter, I hogged out a little of the aluminum bedding block and glass bedded the action. I would like to try this torque method on my rifle. Does anybody know of any problems setting the torque this low on the B&C Medalist?

[1jonzmith]

I tried the same experiment on a couple of two-screw actions that were pillared and fully floated. Saw no difference in point of impact relative to any torques over 30 lb/in. Subsequent action bedding (tang left floating) had no effect on these two rigs.


You came up with the same answer that I did. If torquing action screws makes a differece then there is a bedding problem.



The high dollar actions are usually glued in. That would stop some of the flex.

They are usulay glued in but not always, glueing is a cheap alternitive to bedding. This is mostly done on point blank benchrest guns, (No all, just some.) most long range guns are not glued. Top gun smiths will glue an action mostly because they are asked to do so, but most agree that a properly bedded action is just as good if not better than a glued action. Glue is also used to save weight, when dealing with a 10.5 lbs gun a few oz makes a hugh difference. The custom actions that are pillar bedded dont need the actions screws torqued because they are properly bedded.


Now this, if it is true, would answer ALL my questions. It would also give someone having the "screw" problem something to do to resolve the problem he had that he mistakenly thought was "reality".

Thank you bsek and 82. Thanks a bunch. Got any references on that conclusion?

John

[calling4life]

I have a choate tactical, I torque all my screws to 55 in/lbs...

mine is skim bedded

[82boy]

Thank you bsek and 82. Thanks a bunch. Got any references on that conclusion?
John


What references do you need? I can say I have tried it done it, and talk to other that have done the same and came up to the same conclusion. Trust me, if it made a diference I would do it. Why dont you ask Sharpshooter (Fred at SSS) about it, and see what his answer is.

[SMK Shoe]

Tried it today with a PTA with a 18" McGowan 6.5 BR barrel. third screw was barely figure tight ( Trigger guard) and shot a 1.722" 5 round group. Awful. Gave that screw a 1/3 turn ( snug but not maxed out) and next group was .688". Sat down a did a little figuring out and shot two more groups. .738" and a .612". I know this doesn't really confirm anything YET. we were planning on shooting groups today while torquing with a torque wrench but it wasn't taken to range. Going to do it a little more scientific tommorow. I do think there may be something to this if you have three action screws. Makes sense that if one of the screws is to tight or loose that it is torquing the action or affecting harmonics. Just thought it was interesting that it made such a difference.

[ellobo]

1JonZmith, in answer to your question, on your Swedes your rear screw goes intothe tang.Same on /remingtons and most other Mauser type actions. In a Savage the rear action screw goes into the reciever body not the tang. If the tang on a Savage is resting on the stock and you tighten the body screws you would be putting a bending moment on the reciever at the tang which would put a bending stress at the forward edge of the tang. Not a good thing. That is why the tang should be free floated.

El Lobo

[zap]

This is just a theory.
I am thinking that the reason this type of torqueing works is because it is affecting the barrel harmonics. If you think about it, when the action is locked onto the barrel, it essentially becomes one. There are many things that can affect harmonics. How tight you hold the stock, where the stock, sits on the rest, and many more i am not mentioning. So I definitely think it is worth trying if your groups are not getting any tighter. Like the article on 6br.com said " you have to have a decent group before you even start to try this ".
Nothing to loose :)