how to deal with work hardened ak barrel pin hole?

[yari]

so i got 2/3 of the way thru the trunnion/barrel, drilling for over sized pin, at the very last 1/16 of the barrel section it work hardened and dulled my cobalt bit. sharpened bit went in from other side, and same thing happened. so now ive got a 1/16 ring inside.

will a carbide bit work? really dont want to press it out to anneal it. any ideas?

[tujungatoes]

I'm not a machinist, but Imagine a carbide bit should bet the job done. That's what was recommended to me for drilling a hardened milled receiver.

I was cautioned to be very careful with allignment as they are very brittle.

[CSACANNONEER]

Not sure why you are using a drill bit at all. I use a 1/4" end mill and then ream to final dimension.

[yari]

its a .315 oversized pin. 5/16/.310 drill/endmill. started with HSS endmill ate 2 of em. went with cobalt drill, fail. carbide next, if it doesnt work im gonna smash this thing. its been the worst build ive ever delt with. i think its cursed.

[Gowking]

Are you using a cutting fluid/coolant?

-MRA

[yari]

ya using cutting fluid.

[CSACANNONEER]

Is your drill spinning the correct way for the cutters?

Yea, sounds stupid but, I have seen someone struggle for hours to drill a hole in "the hardest sheet metal ever" and noticed that their drill was in reverse. So, it happens.

[yari]

its spinning the correct way. i just remembered that this barrel came from a bogus build. its a new unfired yugo barrel, came from a populated front half where the guy welded the ends of the pin into the trunnion. good chance i didnt work harden it, but the welding did. anyway its a pita. hoping carbide is the fix.

[tujungatoes]

Dont smash it. If you get too frusted I'll make it go away...free of charge.

[yari]

i wont smash it lol. its become a contest of who will win, me or the virgin. im going to try yelling and swearing it into submission, if that doesnt work get a bigger hammer and scare it a little, then shell out the cash for carbide tools. unfortunately all the places that sell quality tools are closed for the weekend. so we are going to have a long staring contest.

[Ryan in SD]

If you dont bleed during the process the ak gods wont be appeased.

Also drilling from both sides with a slightly smaller sacrificial drill bit then reaming after is a good way to go. Im not sure its worth buying carbide tools for.