Driling SS receiver

Am wanting to mount a scope rail on my Mini 14 Stainless steel receiver. Barrel is removed, hole center is located on receiver ring, and receiver is mounted in vise. Now I find that regular high speed drills won't work. What kind of drill (#31) do I need???

The high speed drill should have cut into the receiver, but there's a good chance the drill was turning too fast and you work hardened the area. Buy yourself a cobalt drill and drill at about 700 rpm.

Mini 14 recievers are hard as hell. Use a three flute carbide drill or a carbide two flute drill. You may also have to spot anneal the hole to tap .

I thought the investment cast receiver was unusually hard as center punching the hole location did not create much of a dimple. Using a center drill, I did not have much trouble raising chips at slow rpm, but once I switched to my standard high speed drill and fluid; nothing. I did not belabor the attempt as I was afraid of work hardening, I will obtain a carbide 3 flute drill and make another attempt. Thanks for any additional input...

Kyocera drills give a good bang for the buck. OSG has what you need but, they are pricey. We use kyocera normally for that size. Already hardened, I imagine 17-4ss, we would probably go ahead and get the OSG for production but, if you are only doing one hole the kyocera should do fine. About 1k rpm, I would start with about .003 fpr and play with it until I found what works. Of course, though I might break a drill or two during set up.

That receiver is "harder than the hubs of hell". You'll drill it OK with a carbide drill, but what about tapping that hole? I've seen a couple of these that were really Bubba ed-Up. Let us know how it goes.

That is now what is worrying me to the point of sleeplessness. Suppose I do drill the receiver with a #32 carbide drill, ream hole .004 out with a cobalt chucking reamer and them what??? I am at a loss to know how to proceed if the tap refuses to cut. I'm not worried about starting the tap straight as I'll start it in the drill press. I know I can hire this done, but am wanting to do it myself if reasonably possible. I have all the necessary tools with the exception of the carbide drill and reamer and these can be had at a reasonable expense. I have drilled and tapped stainless before (years ago) but the materials were no where near this stubborn. There is some sense of satisfaction in doing jobs oneself, but I don't want to trash the receiver. That would haunt my sleep for years to come...

No Sweat, Big 5 has them on sale this week for only $839 . . . . I thought SS minis came with scope rings, no?

Stainless work hardens when you just let the drill sit, push hard so you are making a chip when ever you contact the the bottom of the hole, but back off a lot so it doesn't heat up. Any work hardened spots will be hell when you try to tap. I like stubby (screw machine) drills for these shallow holes. If it feels like you are about to break a tap, I wouldn't think twice about going to the next size bigger drill.