Guys,

I received a rifle with the front scope mount screw hole partially occluded by what appears to be a piece of a scew in the bottom of the hole.

I can't turn the remains of the screw with a pick.

What is the best way to approach getting the piece of scope mount screw out?

I am blessed with a full sized milling machine fitted with a real DRO if that helps any.

thanks,

mstarling,

Try dialing in the hole, dead nuts (insert a long screw in and dial that) and use a left hand drill slightly under the tap drill size, real slow RMP.

If it does not turn it out, at least you can probably get the rest with a pick. It works for me about 80% of the time.

Good luck,

Eric

You can also think about re-tapping to a #8 size at this point too, might prevent this from happening again. What caliber is the gun, does it look like the screw was broken from recoil or from twisting?

mstarling---

You didn't say what kind of rifle but what ever it is, that hole goes all the way through the receiver ring. Pull the barrel and re-drill with a #31 drill. It will drive the broken piece right on through.

It could be you're seeing the barrel shank thread in the bottom of the hole, too.

Guys,

The rifle is a 375 H&H. Screw is broken in the bottom of the hole, indicating a failure due to overtightening a slightly too long screw.

thanks,

mstarling---

375H&H is the caliber. What rifle is it?

Sir,

It is a Japanese Weartherby Mk V. I don't have the facilities to pull the barrel.

There appears to be 6 or 7 unoccluded threads in the hole. Can I just shorten the front screw and blue Loktite this critter and be OK?

Thanks VERY much you all.

mstarling---

In order for a screw or bolt to have 100% strenght it must have as much thread engagement as it's diameter.

A #6 screw is about .135 inches dia. 48 TPI has a pitch of about .021". That means about 6 threads equals full strenght.

With a 375 you'll need full strenght. Take it to a gunsmith and have him drill out the old screw and clean up the threads if you don't have enough. Be SURE to install that screw first to be sure it's pulled the mount down tight instead of bottoming out.

I still think you might be seeing the barrel threads. I dont have a MkV action to measure but I think that receiver ring is about .125 thick.

BTW--- I use LocTite on nothing gun related. It's much better to make things fit right to begin with and torque the screws properly. I've never had a gun screw loosen unless it's wrong to begin with.

[ 10-07-2002, 22:07: Message edited by: JBelk ]