action screw torque tuning?

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joeblow38

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Opinions on the value of action screw tuning? I recently obtain a FAT torque wrench. I have a Savage 10 HS Precision. Official recommendation is 65 in-pounds for these screws, which is about what they were upon checking. I hear that even with an aluminum bedding block, there is value in tuning action screw torque with these stocks.
I'm running handloads @ 46.9 gr of H414 behind 178 gr hornady HPBT match bullets. I've backed off the screw torque to 30 in pounds, and will be having a go with 5 shot groups @ 100 yards during next range session. I'll increment by 10 in pounds up to max.
I know most on this forum will recommend first load tuning, but I have a batch of the 46.9 loads I will have to burn through before doing a fresh batch with varying loads. For now I just want to see if indeed screw torque impacts group size, even with a stock that is marketed as not requiring such tuning.
 
Does it effect grouping - yes

Is it a good way to go about things - in my opinion , no. It puts weird stress on the action and if you ever undo the action screws or they come loose unless you have your torque wrench with you all the time your pretty much SOL for getting those tight groups back. I proper and fully bedded action is and always will be a better method then action screw tuning
 
I bought the FAT wrench about a year ago for the same purpose - tuning the action screws on a Savage .22 BTVS. I found that varying the torque on the two screws had a surprisingly large impact on the groupings that the rifle produced (a high and low group size at 50 yards of about 2.0" and 0.25", respectively), and that it was quite easy to find a 'sweet-spot' for the front/back screws that produced the best grouping consistently. (Other rifles may experience more or less sensitivity to torque settings; I'm just relating what I encountered.)

Having said that, I've finally gotten my hands on some spare screws in the obscure/damn-near-non-existent threading that Savage uses for their .22 line action screws, so I'm going to be bedding the BTVS in the next week or two. I'll do some testing when it's done to compare the accuracy before/after bedding, and to see if varying the torque still has as much impact on group size once it's bedded as well (I expect that the sensitivity to torque settings should be reduced once it's bedded, but may well be wrong).

I understand UltMonk's point, but if bedding doesn't produce the same level of accuracy that you had been able to achieve with the action screw torquing, then you don't have a way to 'fine tune' the bedding to improve things. Unless, of course, you bed and then tune the action screws, but doing that means that we're basically back to where we started. :cool:

Whichever route you go, it's another reason/excuse to have fun at the range and/or in the workshop! :)
 
"...Does it effect grouping - yes..." Yep, but it's also a time consuming trial and error thing. Like everything else about rifles, each one is different.
 
I have a Model 12 VLP, after some digging around I torqued the front action screw to 40 in-lbs and the rear to 30 in-lbs. The one holding the trigger guard on the back just snug. It shot great before that from the factory, and great after I adjusted the torque. I swapped scopes in between so I cannot attest to POI shift. I will tell you that I recently put it into a Savage 11 factory stock with a relieved barrel channel, torqued the screws to the same as with the wooden stock and the POI was exactly the same, dead on. Not sure if I believe in the whole "tuning" aspect but keeping them the same seems to keep POI the same. I think tuning would have more of an impact if there was a bedding issue. I highly doubt that +/- 10 in-lbs of torque will actually put enough stress on an action to make a noticeable difference. Torque down the front screw first and make sure your recoil lug is seated all the way back. Your tang should be floating as well.
 
Consider that for any change in torque to affect rifle tuning, the rifle has to change- or BEND or STRETCH.

for bedding, I consider change a bad thing. A big ongoing headache as it can vary with changes in the stock and/or useage.

When a brand recommends action bolt torque as a way to tune their rifles, I know their bedding is not good so approach with caution. Note that action bolts are not designed to be load bearing devices and do stretch and/or bend.

The best approach is to properly bed the action and stock. Then ensure the action bolts can be tightened without compressing either stock or bend receiver. The action is unstressed but has an interference fit with the stock.

It is consistent and reliable. At which point, the action bolts only serve to keep action and stock from separating. The amount of torque is only needed to keep the bolts from loosening - which is not much.

Works for me.

Jerry
 
I played around with torque settings and trying to improve the accuracy... In the end a really good bedding job, by a talented gunsmith did the trick. Action screw torquing also worked, but not consistently and it was not reliable, nor always repeatable results. I did get some great results and some not so great. Find a really good gunsmith detail oriented and who has a passion for what they are doing. My rifle now shoots consistent .5 MOA with the right load. I'm still refining the load, trying to squeeze it down a bit more, but .5 MOA is quite nice thank you very much. Note, a bad bedding job will not produce good results.
 
I am currently running 62 inch pounds on my 700 in an HS stock that's fully bedded on top of the aluminum. It really does make a difference in my groups. I had an instructors mouth drop open when we put together my HS stock with the bottom metal kit when I bought it from him at the course, we just did "pretty tight" and I shot a group, and it was like an inch an a half, then he said "what's going on?" I thought for a min and said we didn't torque the screws when we put it back together..... he said that he doubted there would be much of a difference, I torqued to 62" (was somewhere around 40ish and unevenly torqued) and fired again, back down to .7's instantly. He seemed a little bewildered as it was a first for him seeing the torque effect the group so noticeably.
 
This is a good test. I'll be zeroing my scope on my new 1 piece 20 moa base in a few days. I have my action screws backed off to 30 in pounds. I'll see what kind of group shows up. Once done I'll take the screws out and do this fit test.

Mystic Precision said:
With the action bolts out of the gun, can you move the action in the stock?

If the answer is yes, then proper bedding is needed.

Jerry
Click to expand...
 
duncansuds said:
not at all, rock solid....which is maybe why he was surprised I guess. Its a bit of a chore to separate them in fact, very snug.
Click to expand...

Interesting.

If you have the tools and want to experiment, put the rifle on a table with a dial indicator on top. Tighten and loosen the action bolts and see if the dial moves up and down. Sometimes you can feel it by hand. Bad bedding, you can even see it move.

If that is what the rifle likes, so be it. Typically, this indicates to me something is moving but......

YMMV.

Jerry

http://www.canadiangunnutz.com/forum/showthread.php/743265-Why-Proper-Bedding-is-Important

Some videos of before and after. Unfortunately, this type of drop in bedding is all too common in factory rifles. Ensures rifles can get assembled in a few minutes with no further fitting... but not always a good thing for the end user.
 
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