1911 Drill & Tap Question

I just know enough about gunsmithing to be dangerous, so here is my question to those that do know. When a 1911 slide is drilled & tapped for an optic's base mount, do the holes completely penetrate the slide?

Mine all did.
It's a pretty thin wall.

Yup

Thanks Jim & Zane--appreciated! I did notice that a 1911 slide doesn't have much meat to it.

brassmaster wrote:Thanks Jim & Zane--appreciated! I did notice that a 1911 slide doesn't have much meat to it.

Check out the current Colt 1911's.
Some of them are scary thin.....

for a four screw rail..

front two screws always.

back two ? sometimes.

jglenn21 wrote:for a four screw rail..

front two screws always.

back two ? sometimes.

The front two. Yes

The back two. Into the firing pin channel? NO!

I agree but I've seen it done....Ok if you hone the tunnel but not the best idea.

I've drilled and tapped two of my own and all four holes are clear through. Once drilled tapping is the worst part. Go slowly and I mean very slowly with plenty of lube. If you break a tap you'll play he** getting it out if it breaks off low.

two words


Tap Magic (original formula)

Greetings,

Be sure to use fine pitch taps. i.e. 6-40, not 6-32, for best holding strength.

A tap guide or other method to keep the tap perpendicular to the work.

Also, be professional and chamfer the tapped hole 90 degrees.

Clean with Trichloroethylene and apply a drop of Blue LocTite to the threads.

Oil the assembly after the LocTite cures, about 24 hours.

Cheers,

Dave

fc60 wrote:Greetings,

Be sure to use fine pitch taps. i.e. 6-40, not 6-32, for best holding strength.

A tap guide or other method to keep the tap perpendicular to the work.

Also, be professional and chamfer the tapped hole 90 degrees.

Clean with Trichloroethylene and apply a drop of Blue LocTite to the threads.

Oil the assembly after the LocTite cures, about 24 hours.

Cheers,

Dave

wouldn't 8-36 be better?

All the scope rails I’ve seen come with 6-40 screws and are countersunk accordingly. To use 8-36 you would need to re-drill the clearance holes in the rail and then countersink them.  So is 8-36 better? Sure it is. But most people don’t want to pay the extra charge to get them. 
Jon

Chris Miceli wrote:

fc60 wrote:Greetings,

Be sure to use fine pitch taps. i.e. 6-40, not 6-32, for best holding strength.

A tap guide or other method to keep the tap perpendicular to the work.

Also, be professional and chamfer the tapped hole 90 degrees.

Clean with Trichloroethylene and apply a drop of Blue LocTite to the threads.

Oil the assembly after the LocTite cures, about 24 hours.

Cheers,

Dave

wouldn't 8-36 be better?

Not necessarily.  Depending on the slide thickness you may not have enough threads.  It takes at least three full threads to get any significant clamping on a screw.  After you have 7 you get almost no increase in clamping...so if your gonna go up to 8 go to 8-40 or better.

Jon Eulette wrote:All the scope rails I’ve seen come with 6-40 screws and are countersunk accordingly. To use 8-36 you would need to re-drill the clearance holes in the rail and then countersink them.  So is 8-36 better? Sure it is. But most people don’t want to pay the extra charge to get them. 
Jon

but its more  better!

1/4"-20 bolts or nothing. Go big or go home.

zanemoseley wrote:1/4"-20 bolts or nothing. Go big or go home.

that is a terrible idea

Lol of course I was joking. My luck someone would actually do that.

I just made a sleeve for my slide so the 1/4 -20's would work.
solid as a rock.
with the matchdot II it's steady as a rock.