Posting drill bit info from feeler, for those that don't want to sort thru 32 pages.
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Thank you, for posting your original info
7.62x39 &
Archilochus and for all their additional input and help !!!
These are the drill bits you will need. Forget about H & L you will not need them since the buffer tube is already finished on these. I already had several of all of these (except the #42 aircraft) but I wanted to start with brand new, high quality bits to do these.
I bought US made, Titanium nitride coated cobalt. I don't use these for anything else. I bought 1 of each size except for the 1/8" which I bought 3 of since it is used so much in doing these. I got them from MSC and it cost me $53 including shipping.
For these lowers it looks like only C, D, and E would be needed. It looks like A, B, J, K, G, and F are done already. I can't figure out what "I" is for.
To do a proper job on the trigger/hammer and safety holes, they should be drilled a few thousandths undersized and reamed to the finish size. I have the reamers - if anyone needs to borrow them, let me know.
"I" bit is for the bolt catch pin which is why you need the aircraft length, you will never get near it with a jobber length bit.
After talking with "
7.62x39" about other tools we will need for our build, he indicated we will also need end mills in 3/8" for the FCG pocket and 1/4" for the trigger slot area. (Thanks for all your help !!!)
I obtained additional info from A
rchilochus regarding the reaming process. (Thank you !!!)
For the trigger and hammer pins, a 5/32 reamer, and the holes drilled with a #23 or #24 'wire gauge' drill. Some people just drill these with a 5/32 bit and don't bother with the reamer - but this will result in a sloppy fit. A drill bit just can't make holes with good tolerances.
For the safety the specs call for a 0.376 reamer and a letter 'U' drill bit. Again, just using a 3/8 drill will work, but will be sloppy. I used a 0.375 (3/8") reamer because I had one, and it worked fine.
It's best to drill the undersize holes with the wire-gauge or letter drill, and - without moving the setup - chuck the reamer and ream the holes. Use the slowest speed on the drill press (or mill) for reaming, and liberal cutting fluid (kerosene or just light machine oil works OK).
You could even turn the drill press by hand if it does not have a very slow speed setting.
If you're using a jig, you might first "spot drill" the holes with the full size drill ( just touching the surface to leave a small indentation). Then drill through with the undersize wire or letter bit, remove the jig and ream the holes.
The undersize bits might not center properly in the jig on their own.
BTW - look for decent US made stuff - avoid the Chinese stuff.
