Drilling a barrel for a front sight ramp

[josquin]

Having never done this before, I have a question. Given that the hole must be quite shallow, it seems to me that it should have a flat bottom, (to match the plug tap) but I've never seen an end mill small enough to fit a 6-48 screw.

Any advice from you gunsmiths out there?

Stuart

 

[Ishootguns]

Are you drilling it in a rifle or shotgun? Usually I just use a drill bit then a plug tape. If its in a rifle triple check your drilling depth before you turn the drillpress on.
Dave

 

[art.h]

make your own, called a D bit First pre drill hole to point depth, breack that bit where twist ends then grind flat to centerline and sharpen the cutting end to make a one lipped piloted cutter and square out hole to depth. More to the point why not sweat solder it on?

 

[josquin]

art.h: I am drilling a rifle (sporterized SMLE Nº4 Mk1) and yes, drill depth will be something to set carefully!

Ishootguns: I hadn't heard of a D-bit before. Looks like it might work, although a 2-bit flute would be better, but it's tricky to re-grind a drill bit only about .140 in diameter, esp. without a milling machine (!) Yes, I could just solder the ramp on with HiForce 44 but there is a screw hole under the dovetail and I like the idea of a mechanical lock, esp. on a part that will be subject to some stress when driving in the sight blade since I don't have a sight pusher. I might be able to modify a #28 bit by slicing off the end and touching up the flutes with a tapered carbide bit in the Dremel to allow it to flatten out the bottom of the hole.

Stuart

 

[guntech]

It is very easy to grind a drill bit flat... the trick is to not engage the hole with the bit spinning... the flat bit may catch on the edge of the hole. Once the bit is in the predrilled hole, turn the drill on and lightly cut the bottom of the hole.

Drilling a shallow hole and the tapping of it is best done in a drill press for the total operation. If you are trying to do it free hand you are making it very hard on yourself. The success rate is lower. You will need to start the tapping with a sharp plug tap and finish with a sharp bottom tap.

 

[josquin]

Thanks, Dennis. I will definitely be using a drill press (!) as I wll need to level the barrel to make sure the hole is straight. I already have two 6-48 taps, one taper and one plug (home-made by grinding off the tip of a taper tap- much cheaper than buying one). I also drilled out the handle of my T-handle tap wrench to mimic the $60 B-Square one, so I can put a piece old drill bit into it and chuck the other end in my drill press to hold it vertical.

I was looking in the Brownell's catalogue (VERY dangerous as I already got a bunch of stuff from them last week) and eyeing the top Dead Center Punch but I think that if I level the barrel properly I should be OK. Fortunately the SMLE has a flat ahead of the breech so that gives me a reference.

Stuart