Home Forums Hunting & Shooting Gunsmithing 6/48 to 8/40 thread cleanup

I have a 700 that might have its base hole alignment slightly out of wack, not much but enough to notice on a collimator. It might be the mounts or the screw holes. I mounted DNZ 2 piece mounts(which suck) and got that result. I ordered talley lightweights to see if there is a difference or not. Scope is a Zeiss DL which has given zero issues in 3 years I have owned it .

Will 6/48 to 8/40 improve the alignment ?

It can if you have the means to precisely drill it.

DF

I don't have the equipment to do it, will leave that to a good gunsmith.

Good idea. Will need machinery to cut in the edge of an existing hole.

If the alignment is too far off, that could yet be a problem.

A good smith will sort it out.

DF

Other then that if it is indeed the problem, a beautifully made rifle . If it is worse then that I am calling Remington

I once had a M-70 SS Classic with holes so far off, the smith had to offset the factory holes, drill bases to fit the new screw holes. Most aren't that bad.

You can't drill a new hole if the footprint of the larger screw doesn't cover the old hole. In this case it wouldn't; it would have left a half hole exposed and that won't work. Offsetting was easier than welding the old holes and starting over.

DF

I had a 25-06 SPS Stainless that was an absolute hammer . Problem was even with the windage adjustments all the way out I could not get it on paper. I let a Gunsmith have it for a song and dance who was going to fix it

Once you offset the holes and drill bases to fit, you're stuck with that set up. In my case, we used SS Talley bases on a SS rifle.

With a LR rifle, mounting a Picatinny rail with offset screws and just leaving it there may be an option. Filling the original base screw holes with screw heads and epoxy makes it look better. With a scope mounted, it's hard to tell.

I'm amazed how crooked factory holes can be. Surely they have jigs and equipment to drill perfectly aligned holes.

Must be Friday, end of shift guns. No excuse for that.

The fix for a bad one is not always pretty.

DF

I don't think it is that bad, its problem is my other rifles are pretty well made even though they are factory rifles

I have a Winchester 75 Sporter some dimwit drilled extra holes in the receiver before I got it. I got a great deal on it, so I picked up some Leupold gunsmith bases, shaped them to fit the receiver on my mill and then took some careful measurements and drilled/countersunk them to fit the existing screw holes and line up properly with the barrel centerline. Looks like a factory job and works great. If I were to do it again, I would do the same thing or get a long picatinny rail and drill/countersink to match the screw holes.

Bob

What he said. Buy blanks, have them drilled to fit your rifle. Hasbeen

I received some Talley lightweight rings today and mounted them on the rifle, problem solved . The DNZ mounts were off

Good deal.

Better than the rifle being off.

DF

RIfle is fine, DNC mounts are going to be returned even with my lapping job they sucked They were simply not machined correctly.

I've had this done. Be sure the gunsmith knows what he's doing and uses a mill to recut the holes and not a drill. A drill will tend to follow the existing hole.

This will work fine provided the holes aren't too far off.

Paul

You can get blank, undrilled bases/Picatinny rails, drill to fit gun screw holes.

A good smith with a mill, not a “bubba” job.

DF

I should take offense at that.

Neither have a mill nor am a gunsmith. Have modified bases with hand tools and a drill press and they came out fine. Not economical, took a lot of time and patience to make it come out right. But it can be done. One of those projects you do just to see if you can.

How do you mark the screw holes to drill a blank base?

I could handle the drilling. Lay out would be my main issue. You can't see the holes with the blank base in place.

DF

Actually I used a base with holes, kept the holes and worked on where the rings clamp on. The hard way but I already had the bases and figured what the hell, why not try. Add a little metal here, take a little metal there. I'll defer to people here who've done that type of layout problem.

Kind of the Bubba way I guess but if you practice your metalworking skills it can come out nice.

Dirtfarmer, since nobody wants to reveal their secrets, I'll take a shot so they can mock me and maybe reveal all.

Mark a datum line top dead center on the receiver parallel to the bore. Center the base on that line and mark. Measure carefully to locate the holes. Drill small to give yourself some room for correction.

Maybe something easier can be done with a drilling jig but I don't have one. If you have bases with holes you could use that as a template and mark holes using your offset.