Oversize Base Thread / Permanently Attach Rail?

[Kenobi]

I picked up a Remington 700 ADL from Academy to use as a donor action for a future build. I took it home to clean and lube and test fitted a scope base to the action. When I tried torquing the base screws to 25 in/lbs they just didn't feel right as they bottomed out. Kinda crunchy like they might not have been threaded correctly. I backed the screws out, inspected them and torqued them down again and they torqued without any give, but that caused me to worry about whether the threads are going to strip out in the future.

SO MY QUESTIONS ARE THESE. Has anyone ever re-tapped the base holes to accept a larger screw? What screw size and thread pitch did you use? AND, has anyone ever tried permanently attaching a Picatinney rail to their action via silver-solder or other means? Who did the work? What means were used? How rigid was the end product?

I like the idea of permanently attaching a rail to the top of the action since many custom actions these days come with a rail milled as a part of the action itself, so I'd really like to know you guy's experience one this regardless of whether I actually have a problem with my threads.

 

[ZSteinle]

they can be drilled and tapped for 8-40 screws.

 

[Kenobi]

they can be drilled and tapped for 8-40 screws.

Thanks for sharing that specification with me!

I figure it's just as well. The factory provided screws feel too small to really stand up to hard use anyway. I'd consider a larger diameter thread with more bearing surface to be an upgrade in any event and would probably have them done when I get the rifle setup the way I want anyway, regardless of whether mine are stripped.

When I say "hard use" mentally picture my buddy having a rock break loose under his foot causing him to fall backwards onto a boulder on top of his rifle. At first I was worried he'd broken his leg, but once he shook off the fall and we got back after the elk heard I started worrying about his rifle and all the potential failure points that could have been stressed by that fall.

 

[MagnumManiac]

Thanks for sharing that specification with me!

I figure it's just as well. The factory provided screws feel too small to really stand up to hard use anyway. I'd consider a larger diameter thread with more bearing surface to be an upgrade in any event and would probably have them done when I get the rifle setup the way I want anyway, regardless of whether mine are stripped.

When I say "hard use" mentally picture my buddy having a rock break loose under his foot causing him to fall backwards onto a boulder on top of his rifle. At first I was worried he'd broken his leg, but once he shook off the fall and we got back after the elk heard I started worrying about his rifle and all the potential failure points that could have been stressed by that fall.

There is another option, 'chase' the existing threads with a 6-48 tap, then have the action drilled for pins to screw and pin the rail, that way, if there is a problem with the threads, the pins hold the rail from moving. I always 'chase' threads on second hand rifles, you never know what the previous owner put in there.

The finer the threads per inch, no matter what diameter, is stronger in tension force, so the larger 8-40 thread size, in fact, has less tension force than the smaller thread size.
If you want to drill and tap to 8-40, it MUST be done by a competent machinist in a mill, do not attempt this yourself. I would get the pins done at the same time.

Cheers.
lightbulb