8-32 scope base screws on reminton 700

[ungerstruck]

Is there a fixture to convert a remington 700 scope base screws to 8-32 on a drill press

I have access to a few CNC mills/lathes but not enough to do the work on, so I was thinking of making a a fixture out of a solid shaft boring it out to the size of the action and drilling a few holes into it for the action screws on one side and the scope base screws on the other then use it as a pilot for a drill press.

For the people that have done it is this something you would use or is there something better than this, its my first idea but I think it would work.

 

[rcmodel]

A simple drill press vice will work as well.

The holes are already drilled.
And the #29 tap drill for 8-32 will follow the existing treaded hole.

So clamp the receiver in the vice, align the existing hole with the drill, and clamp the vice to the drill press table.

Drill out the hole, take the bit out, and chuck the 8-32 tap.

Then tap the hole by turning the drill press chuck in & out by hand.

If the vice didn't move on the table, and the table didn't move on the drill press?
The tap will be in perfect alignment with the hole you just drilled out larger.

Rc

 

[ungerstruck]

Hi rcmodel thanks for your reply, but I have to ask have you done this before like this or seen someone else do it first hand?

If so then this seems like a very easy job other than tapping the tiny 8-32 in 416 stainless steel action.

thanks for your input.

 

[rcmodel]

Have I done this before???!
Well yes I have as a matter of fact!

I was an Army AMU gunsmith back in the day, and a non-professional hobby gunsmith since about 1960.
I was also a tool & die repairman in real life for half my 36 year working life.

So yes, I could say I have done that a 'few' times.

A pre-drilled hole don't get no easier to drill one size larger and tap for a new thread size using the method I outlined.

If you don't let the vice set-up move on the drill press table, there is zero chance of binding a tap off center and snapping it off in the hole.

Just be sure and use a *high quality tap, plenty of cutting oil, don't rush it, and back out and clear the chips off the tap more often then you think you need too.

(* Meaning no .99 cent tap from the Chinese junk display at the hardware store.)

BTW: A 8-32 Tap isn't tiny.

A 2-56, 3-48, or 4-40 tap is tiny when dealing with stainless, or aluminum.

rc

 

[HankB]

IIRC, the standard screws for a 'scope base are 6-48.

I've read about drilling out the small factory threads, tapping, and replacing with larger screws, but not 8-32; invariably the finer 8-40 threads commonly used in gunsmithing applications were used. Some custom rifles come threaded 8-40 from the factory, especially when chambered for larger cartridges.

I'd think twice about the TPI here before proceeding.

rcmodel, in your experience is there a "preferred" TPI for this application?

 

[rcmodel]

I have never seen the normal 6-48 screws fail on normal recoiling calibers up to .30 & .338 Magnums when properly torqued with blue lock-tight under the base, and on the screws.

If they were failing often enough to notice?
All the firearms and scope mount companies would have stopped using them 50 years ago.


And you are correct HankB.
8-40 would be the gun thread standard, not 8-32.
The finer threads are much stronger.

rc

 

[ungerstruck]

Sorry to confuse you my rifle threads are not failing I only wish to do this because the base I'm looking into has the option to have holes for the #8 socket head cap screw, and I love learning new gun smithing techniques.

Also if I were to re tap to 8-32/8-36, I know 8-40 is the gun thread and that it's most likely stronger than the 8-32/8-36 but either of those are much stronger than the 6-48 and both much more readily available.

 

[rcmodel]

All you would be doing is confusing people in the future who buy the rifle from your estate sale and find out you Bubba'd the receiver with machine screws instead of gun thread holes.

I would suggest you order a copy of the Brownells Gunsmith catalog, and read the tap & screw section several times.


Brownells Catalog
077-100-000WB
$5.00

http://www.brownells.com/aspx/general/catalogs.aspx


You don't buy scope mount socket-head screws at the John Deere Tractor store just because they are there.

Rc

 

[HankB]

I have a .375 H&H with four standard 6-48 mount screw holes tapped in the receiver . . . but when I put on the base (1-piece Redfield) I noticed that there were only three drilled & counterbored holes in it, so I added a fourth myself. So far, so good, over at least several hundred rounds.

Even if standard machine screws are more available, I'd go the extra mile NOW and get the proper 8-40 screws - after all, the job should last for DECADES so a little extra effort now is worth it.

Also, aside from the threads, quality 8-40 screws from some place like Brownell's are probably made of stronger steel than something from the local hardware store. (An encounter with exceptionally poor quality screws from Ace Hardware - in a project unrelated to gunsmithing - made me skeptical of hardware store screw quality.)

 

[ungerstruck]

Thank you for sharing your experience I will most likely be trying this in the future, also I was thinking of using a 8-32/8-36 but now seeing how available the taps and socket head cap screws are at brownells I'll be using 8-40.

Thanks again for your sullotion to this job.

 

[MachIVshooter]

now seeing how available the taps and socket head cap screws are at brownells I'll be using 8-40.

Good decision. Course threads get more engagement per thread, but are not a good choice when the hole is very shallow.

I'm still not sure I understand why you want to go larger, though. I've never had the #6 screws shear, not even on my lightweight 700 BDL SS in .375 RUM.

BTW: A 8-32 Tap isn't tiny.

A 2-56, 3-48, or 4-40 tap is tiny when dealing with stainless, or aluminum.

My thoughts exactly. Lol.

Try running 0-80 and 00-90 through 304 stainless or 6061-T651, you'll get a whole new perspective.

The head and pan bolts are 0-80, the rocker arm screws and con rod screws are 00-90. The billet was either 7075 or 2219:









M3-0.5 into 20mm+ blind holes is also a blast, and tapping a proprietary tool steel that is almost as hard as the tap with #2-64 is fun.......