Effects of Action Screw Torque in Precision and Ballistics
- Thread starter Sniper King 2020
- Start date
I don't watch much YouTube honestly. I don't have much time with 2 little boys and my business,. When I do, and have watched some other YouTube channels, I find that there's so much rambling and going on and on about crap that isn't on topic with what the video is supposed to be about, I lose interest in it. Most of them do too much blabbering about unrelated crap in between talking about what you are actually trying to watch, and at the beginning of the video that it's hard for me to watch it. I also just generally prefer reading the information vs watching YouTube most of the time.Cool, appreciate it. What other YouTube channels do you watch?
Thanks for the response. I am the same in that I don’t have time for lengthy videos that don’t “land the plane”/get to the point. I watched a video for the first 30-40 of the 60+ minutes of Litz and Cortina about tuners that was pretty much worthless and was really disappointed in what I watched. Luckily, I was doing my routine cardio workout so didn’t waste my time watching it. Anyway, don’t want to take up much of your time but appreciate the response and I do plan on publishing a book that has more detail about these tests and the results. I think it best to put info out there that is visual/audio and just visual. Better to have multiple modalities.
Interesting.
A few questions. What is the maximum you can torque the screws and what is the effect on precision. Assuming pillar bedded with aluminium pillars.
The effect was so great that I would bet my last shiny penny they would generalize to a rig like mine. If the rifle is not set up to shoot small most of the time then the variability in groups may wash out any effect. Just examine Bryan Litz tests on group variability to see how rigs with a limited set up produce wide variability in group size and shape. You have to have a well tuned rifle and we’ll set up rig to detect effect sizes in the small to middle range. This effect size was fairly large so I’d be willing to bet my other last shines penny it will generalize to other rig types assuming they are well tuned and we’ll set up. Also, the shooter has to know how to deal with wind and other factors. For your particular rig, I suggest brining a torque wrench to the range and try it on yours. I would be sure you have a good tune, the rifle is set up well, and you shoot in the same atmospheric and wind conditions so those do not affect your results.
Max I’ve heard from a lot of smiths is 75 in-LB for small cal with aluminum pillars. My test shows 60 produce great precision (the groups shot with 60 are the same size and shape typical of this rifle with the same bullets, primer, powder charge, etc. so 60 seems to be good for precision). I definitely wouldn’t go lower than 60. For magnums, a lot of smiths I know recommend 100.
My Vision chassis gives a max torque value (which is written on the bottom of the chassis by the rear action screw) for the action screws of "70 lbs". So, I suspect somewhere in the 60-80 in/lbs is what the vast majority of non magnum or SA rifles would fall into. I would imagine the manufacturer of whatever stock or chassis gives a max value somewhere , but I've always been told "around 65 lbs" .
Keep in mind fastners yield when you torque them. The more you torque depending on the steel and heat treating of the fastner, the more they stretch. Steel is not very elastic. It's a good idea to replace your action screws every X cycles depending on those factors.
It's common in the AR world to play around with torque values on barrel nuts to see what shoots better. For bolt guns, anything from 45-65 is more than enough.
It's common in the AR world to play around with torque values on barrel nuts to see what shoots better. For bolt guns, anything from 45-65 is more than enough.
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