Chamfering hole when drill and tap for 6-48 oval head screw

[Dave in WI]

I need to drill and tap a barrel to move the front ramp back. Ramp is soldered on currently, so no screws.. Plan is to drill through ramp in bottom of dovetail and drill and tap barrel 6-48. Is there a larger drill size I can use to countersink new hole in ramp to match angle of taper on screw head to get it below surface for the sight to slide in?

 

[WSnyder]

You can get piloted countersinks for that operation. Not sure how easily sourced one would be for a #6 oval head because I've never looked. @Will Henry mby he knows

McMaster #6:

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

Note: a flat bottomed hole uses a counterbore, angled bottom hole uses a countersink

 

[ELR LVR]

Standby to receive...

 

[ELR LVR]

I had to do something similar to fix a scope base to get the holes to line up properly and accurately
I got a #6 scope base screw countersink from Brownells, the nose is a NON CUTTING pilot
I was referencing the numbers on the box.... but come up with nothing so far at brownells
(Will forward when I find the link)
I used a 1/8 end mill to accurately locate the hole the countersink would follow

 

[ELR LVR]

Here it is
They have them for #6 and #8 screws
Unfortunately says out of stock on the #6
it is from Maford.com though so maybe check or call Brownells to get the Maford part # if that helps

BROWNELLS WEAVER 6-48 SIGHT SCREW COUNTERBORE | Brownells

Check out BROWNELLS WEAVER 6-48 SIGHT SCREW COUNTERBORE | Brownells available Online at Brownells Today and many more Scope Mounting Tools products are available in our Optics Department.

www.brownells.com

 

[Sniperhandle]

Everyone should have several different sets of these gun screws, I have some from Brownells, Forster and I also have set by Pachmayer.

TACSTAR MASTER GUNSMITH SCREW KITS | Brownells

Check out TACSTAR MASTER GUNSMITH SCREW KITS | Brownells available Online at Brownells Today and many more Shop Supplies products are available in our Tools & Cleaning Department.

www.brownells.com

 

[tobnpr]

Ramp is soldered on currently,

So...why not solder, again?