Gunsmithing Action screw torque

[LC 6.5 Shooter]

What should torque be on stiller tac 300 action in a manners t4a stock (bedded).

I just checked a rifle I bought. Front was at 50in/lbs and rear was 30in/lbs.

 

[LRI]

In 2004 I was introduced to a guy named Jerome Sailing. He lives in WA and makes his living designing/proofing fasteners for the aerospace industry.

I asked him this question and he answered it with a paper that he wrote. 90% of it was outside of my ability to understand, but the summary was that with a typical SS screw in 1/4-28 pitch made from 300 series stainless steel, the applied torque should not exceed 40lbsinch.

Grade 5 carbon steel screws will tolerate a little more, upwards of 50lbsinch.

This assumes your working with a female hole that has the appropriate tensile strength. I would have to accept that actions made to 40 Rockwell C scale (or higher) achieve this in spades.

The screw is little more than a spring. The threads are just a means of applying the force required to stretch it so that it can do the work of squeezing things together.



Your question specifically:

First, do a test. remove the front guard screw. Now snug up the rear. If the front of the gun starts to levitate off the stock, then you have an issue. A bedded stock should not move around like that. This was the plague with many chassis type setups early on. The tang of the receiver was not supported at the screw hole. The back end of the action acted like a see-saw.

Assuming it does not rock on you, then you should be able to snug it up to 40-50lbsinch without consequence. If it does, then its prolly best to return the rear screw to 30lbsinch. A little diligent testing at the range will answer this once and for all.

At 30lbsinch its basically just "holding it" without applying any real tension. Not ideal, but there's a zillion 1.0 version AI chassis stocks out there running killer numbers that are assembled exactly this way.

Hope this helps.

C.

 

[Greg Langelius *]

When we set up the SH Ghost Dancer Rifles in 2001, our resident gunsmith provided the torque info, sourced from a gunsmithing magazine.

Savage 2001 10FP action, 25 in/lb, front and rear.

In 1965, IBM sent me to their electric typewriter mechanic school. They seldom used torque wrenches, but did teach a method for applying torque. Starting with a clean, dry bolt and hole (clean with trichloroethane [these were the days before OSHA and EPA. Alcohol will also work, but dries slower.] and thoroughly dry), cautiously apply torque until the screw binds, them jumps further.

Stop there.

Not especially precise, but they stayed torqued, and didn't break.

Would I do that with a rifle? Never with a critical, stress related bolt. I have, but am now using a torque wrench.

Penny wisdom quickly turns out to be pound foolishness.

Greg

 

[LRI]

trichloroethane!

I once worked for Paul Rossi and we'd mop the floor in the engine assy room with that stuff, lol. Awesome chit for cleaning up heads after lapping valves too.

A very close friend of mine narrowly avoided a death sentence last year Bone cancer, traced back to Trich. 20+ years of basically brushing his teeth with it back in the 80/80's in machine shops. (Apparently the medical folk can pick it out of a police lineup pretty easily now)

He beat it, but it didn't come easy.

Hoping I dodged that bullet.

 

[supercorndogs]

Scary the long term ramifications of some of the "safe" chemicals we have used. Its a good reminder to protect yourself from the "safe" chemicals we use today.

 

[carlsbad]

What should torque be on stiller tac 300 action in a manners t4a stock (bedded).

I just checked a rifle I bought. Front was at 50in/lbs and rear was 30in/lbs.

How did you check? the only way to check is to mark the heads of the screws, back them off, and then increase torque until you get them to the same place. Torque required to loosen is meaningless.

 

[smoooth1]

I have always read 65 in/lbs for Rem style actions.