Action screw length?

[Drolds72]

just got my McMillan Tooley-MBR stock for my Borden BRM action. Pillar bedded. Perfect drop in fit! Wondering if there was a specific procedure to determine how long the action mounting screws need to be? I slid in a long Remington screw, marked the top of the pillar, and pulled out and measured. That all there is to it, or is there a better way? Or is this a trial and error process? I would still need to add in the depth of the action so screw did not bottom out in blind hole, or hit bolt.. Secondly- have custom screws made, or can I shorten some longer ones?

 

[Cold Bore]

I use the longer screws available from Brownells.

Run them in until they touch the bolt, get a good idea of length, then start grinding (with a file). Same at the tang.... run it all the way up through, see how much extra I am dealing with, and start whittling.

Then it's trial and error; I run the front bolt up in and see if it touches. If so, file a bit more. Once it doesn't touch, and I can freely turn the rifle's bolt without the action bolt touching the lugs, I then file off just a bit more for insurance and call it good.

I figure that gives me the max amount of engagement, without interference.

There may be a more technical way, but this always works for me (at least on my M700's).

 

[Dans40X]

there are several ways to skin a cat!

dial caliper depth readings will be direct

I believe Forster,Darrel Holland,Brownells manufactures action screws that will suffice

 

[M-61]

A rough guide would be: If the materials are the same, 1-3 x the diameter, is sufficient depth. Bottoming in a blind hole is to be avoided. I see nothing wrong with shortening longer screws to the correct length. I believe it is something like the first 3 engaged threads carry 70% of the load.
I am sure there will be a machinist who will chime in with more accurate info.

 

[Drolds72]

awesome information- thanks much! this was how I was going to tackle it, but just wanted to be sure. I have the correct sized die to clean up screw as well... Forgot to ask before, but with pillars, is there a recommended starting torque that you would use? I have read anywhere from 30-60 inch lbs....

 

[Alex Wheeler]

What you want to be sure of is that they are not bottoming in the action. Turn them couter clockwise until the bolt drops off the thread starts. Thats your start point, now count the rotations until the bolt is tight. Take the action out of the stock and repeat. Make sure you can thread the bolt in farther when the actions out, if you cant the bolt is bottoming out in the action and needs to be shorter. I usually end up with around 3 turns of thread engagement. Make sure they thread in with zero resistance, no rubbing. If the bedding is good torque really doesnt matter. Just make them snug.

 

[Dusty Stevens]

I put a sharpie mark on the end of the screw then see if it hits the bottom. K.I.S.S.

 

[Gene66]

I use a belt sander to shorten action screws ,
Works great, and does not bugger the threads

 

[Drolds72]

I use a belt sander to shorten action screws ,
Works great, and does not bugger the threads

60 or 80 grit? probably does not heat up as much as a bench grinder would... Hmmm..

 

[savagedasher]

60 or 80 grit? probably does not heat up as much as a bench grinder would... Hmmm..

Depend on how much they have t be shorten
Make sure they don't bottom out or extend through a hole . Larry

 

[Gene66]

I use 120 grit. I have the belt sander upside down and hold the action

screw with my fingers, if it get to hot to hold, I just stop and let it cool

 

[M-61]

When shortening a bolt (screw) I like to run the appropriate die all the way up. Sanding, filing, wheel, hacksaw blade, whatever method used when it is cut I run the die down as it will clean the threads somewhat and you do not struggle starting a die on some crunched threads. Then back up the bolt to be sure. As stated above holding it with your fingers prevents over heating it.
Remember there is no strength advantage to a length that exceeds 1-3x the bolt (screw) diameter.

 

[Drolds72]

Depend on how much they have t be shorten
Make sure they don't bottom out or extend through a hole . Larry

yep- got some good advice on that.

When shortening a bolt (screw) I like to run the appropriate die all the way up. Sanding, filing, wheel, hacksaw blade, whatever method used when it is cut I run the die down as it will clean the threads somewhat and you do not struggle starting a die on some crunched threads. Then back up the bolt to be sure. As stated above holding it with your fingers prevents over heating it.
Remember there is no strength advantage to a length that exceeds 1-3x the bolt (screw) diameter.

Yep, in my mind I envision putting the die all the way down on the screw, then cutting/grinding it, and using it to clean up threads as I back it off. I have not measured thickness of action, but not sure its even 1x (.25") the diameter of the screw. Planning on using as much depth as possible without bottoming out bolt or allowing it to hit the Action bolt.

 

[Drolds72]

Just wanted to thank everybody again for the tips. I carefully ground down bolt to what I needed to for 3.5 turns, and used a sharpie on the end of the bolt to verify it did not bottom out in blind hole or touch bolt lug. Torqued to 45" lbs, and ready to get scoped! Suppose to be near 50 here in Minneapolis- might get a chance to shoot it this weekend!