Torqueing guard screws
chris8X57
Member Posts: 1,229 ✭✭✭✭
I recently read my dog eared copy of 'The Accurate Rifle' by Warren Page, and nowhere in it does he mention torqueing guard screws. Back in the day, these gentlemen were shooting average aggregate scores of 1/4" at 200 yards with their rifles built on Remington, Shilen and Mauser actions.
Page discusses proper bedding at length, and yet, the order of the day was to "tighten guard screws" with a screwdriver. He does mention, on a Remington, to tighten both, and then back off the forward screw one quarter turn.
These days, you see online folks discussing torque this screw to xx inch lbs., or that screw to xx foot lbs. My question is this; is this torqueing with a calibrated torque wrench necessary, or just gimmick? Just another thing to add to the gunsmith's workbench or tinkerers toolbox..?
I built my first rifle in 1976, and feel that I have built some extremely accurate rifles in my day. To this day, I have yet to put a torque wrench on a guard screw, mostly because I feel that woods and composites ( even in the same firearm model) compress differently, and even with pillar bedding, there can be deviations.
Not wanting to generate arguments, but I am interested in hearing your thoughts, and am I just an old fogey resisting change...
Best, Chris
Comments
I use a Wheeler Torque Wrench for every application I can. It gives repeatable accurate measurements of the torque applied, it is especially important when mounting scope bases and rings. Each fastener has a specific load it is designed to operate under. Getting that load or bolt stretch correct is wise.
Its also wise to relate the required torque to the specific application. It sounds like an obvious statement until you look at it a bit more in depth. The torque screw poundage will be different on lets say wooden and laminated stocks as opposed to chassis based stocks using the same action. Its also different based on bedding type because one bedding material may have more flex than another. Even after you get the torque right its something you should check after your initial test firings and then again after each range session to confirm there is no significant change. This is a good idea for just about any screw on a gun that could shake loose. Old Fogey or young gun, you shouldn't resist that which will only make your experience on the range better!
I've found this to be of some help, click on the Brownell's link for more info..
https://precisionrifleblog.com/2013/03/22/rifle-screw-torque-settings-specifications/?subscribe=success#blog_subscription-2
This sounds like an experiment in the making: does different torque pressure affect the accuracy of a known accurate rifle. If someone does it please report your findings.
Different torques always affect accuracy, thus the reason factories specify the torque in in/lbs for each bolt. Composites of fiberglass usually around 55 in/lbs, aluminum chasis stocks such as HS Precision or Bell and Carlson 65 in/lbs, wood stocks vary from manufacturer to another, synthetics/plastics are different as well, as are stock with aluminum pillars installed in either wood or fiberglass..
Guard screws are tricky since the rear screw is generally the rear action screw whereas the front is not. Overtorquing the front action screw can change the torque on the rear screw etc. The front action screw is important in that it stabilizes the basic "center" of the assembly which supports the barrel tenon.
If a bolt action centerfire rifle's action is PROPERLY glass bedded and the barrel floated I prefer to not use a torque wrench. I can feel when the action screws are properly tightened.
I can also remove and re-install the stock and the rifle will still shoot to the same POI.
This is why I prefer glass bedding my own guns.
I have a way of testing using micrometers as to when the rifle is properly bedded as no movement, bedded so as the receiver action is dead. Been doing this for years.