How would you fix this?

[cdhknives]

It appears to be a broken off scope mount screw with a off center drilled hole in a failed attempt to remove it. This is in an older Remington model 700 ADL.



My plan is to finish the existing hole to see if it relieves the screw enough to get the remnants out with an ez out or even pick it...pry it away from the original hole.

Failing that I was considering trying to figure out the milling attachment for my lathe and see if I can plunge a 1/8" endcutting mill down the original hole, and then follow it with a #28 drill bit in preparation for retapping to 8-40 thread.

My goal is obviously to not have the new hole for the #8 screw follow the off center current hole.

Any suggestions and advice are welcomed before I mess it up worse.

 

[swatson144]

I'd try a left hand drill and reversed drill motor, to get the stub out. Follow it up with a threaded piece of center drilled silver steel in the original threads. Drill to an appropriate size and tap. Oversize all the mount holes to the same thread unless the owner would rather not.

Butchery is hard to fix.

Steve

 

[cdhknives]

For better or worse I'm the owner...and I'm barely learning how to use my grandfather's old lathe. BUT, I bought the rifle as a learning project, so it's time to learn! Now I know why the guy traded it off so readily...

I have already ordered the replacement 8-40 screws, drill, and tap from Brownells and have no problem with sizing up all the mount holes. Man, that thread size is hard to find except for the gunsmithing supply stores!

 

[Ray C]

Oh brother, you picked a doozie project to learn on... Receivers are about has hardened as you're going to find. If you're lucky, it's only case hardened.

Anyhow, what Steve said... LH drill first. That's what the 'smiths used when I worked at a gunshop...


Ray

 

[Bobby Bailey]

Most receivers are not hard and drill real easy. Some of the older (1903, 1917 ect.) have a hard skin. The Rem. 700 should not give any trouble. Make sure your set-up is good and rigid to keep the bit from wandering into the off hole. The best would be to use a mill.
Bobby

 

[tripletap3]

Even if you get it out of the off center hole the now off center scope base will make it useless. Without seeing your scope base or mount, I would if possible relocate and re drill/tap new holes right behind those. If the old ones show I would TIG weld those up and refinish the top of the receiver.
Drilling barrels and receivers are the scariest things I do. When drilling into barrels there is a thin line between success (enough threads to hold, also the reason for such fine thread screws on guns). and failure (going too far or all the way through). If you screw it up you cant get a new piece of stock and just start over you have to buy a new barrel. That is if you can. I use a center drill to start the hole or in difficult cases such as with hard metal I may mill a small flat spot where I want to start the hole taking the curve factor out.

 

[cdhknives]

Thanks for the info guys!

The mounts are simple 2 piece Weaver mounts.

I got the old screw material out last night. The current hole is #6 and I intend to redrill them all for #8 screws...as soon as my order from Brownells arrives (next week). I'm wondering if I fill the hole with JB weld to give the bit more uniform resistance if the new hole can be drilled true. Any remaining JB weld can be threaded and would be covered by the base...and I usually epoxy bed bases on my rifles anyway (same as bedding the action). I suspect I could get 80%+ of the threads in metal...IF I can keep the drill bit running true to cut the hole.

I don't have quick access to competant TIG welding, and drilling and plugging isn't much easier in my opinion/skill level. I do plan to Duracoat the whole rifle once I have all the machining done, so surface appearance and texture is less important than average.

 

[Bobby Bailey]

If you're not comfortable drilling /plugging and don't have a mill I would take it to someone to have it done.
Bobby

 

[Alphawolf45]

A drill bit is far too limber to move the edge of the hole over into proper alignment unless the original hole is first filled with metal that is just as hard as the barrel itself...What I do is grind the very end of a centercutting endmill down to the diameter that is required and use it like a drill..A grinder on your lathes toolpost and an endmill in a collet or centered in a 4 jaw chuck will enable you to grind a HSS endmill to diameter you need.

I spin fixture endmills under a surface grinder wheel..I find myself doing such things on almost weekly basis.Never throw away a dull endmill as they can be remade into useful tools.

 

[cdhknives]

The problem I have with drilling and plugging the hole is getting the inner surface correct. It opens into the lug clearance area, so if it is left long it will prevent the bolt from closing, too short and it'll be weak with too few threads holding. Contouring to the interior curve would seem ideal but that is the part probably beyond my current skills. I don't have a barrel wrench or I'd just pull the barrel, plug it, and cut the stub off from the inside.

Like I said earlier, this rifle was bought as a learning project. It has made its one trip to a real gunsmith for squaring and installation/headspacing of the new barrel. The rest is on me...all I have in it at this point is the gunsmithing work and one offshore fishing rig I hadn't used in a decade.