Model 12 FV

[1vakid]

Well my new barrel should be here in 2 weeks. Just now I decided to install my pictinny base on the action to check fit. Well, it appears that the front base hole on the action is buggered up. Screw will thread on about 2 turns and it will go no further. What tap size do I need to chase the threads and clean them out? HELP!!

[J.Baker]

Should be 6-48 if I remember right.

[RustyShackle]

You might want to try a different screw in the hole. And it might be a little piece of crud stuck down in the threads, you might try using a scribe and following them a couple times. See if anything gives.

I thought a standard tap would not work in the receiver base holes? Maybe I just completely misremembered reading that once upon awhile. Or maybe it was predicated on the bbl being installed...

[celltech]

Use a bottom tap as there are not many threads to work with. I have had to chase several and the tap worked great.

[1vakid]

No crud. Tried several screws and they all go in just a little bit.

[short round]

Wait till the barrel is off & clean thread with tap.

[OLEJOE]

Wait till the barrel is off & clean thread with tap.
+ and it is 6-48 tpi. When I installed the new barrel on mine, I chased the threads on all base holes. I do this on any new rifle I’m installing a base on. If the base(s) are already installed, I remove them and do it anyway. You can’t properly torque screws with crud in the threads.

[want2ride]

I always use a tap on the threads. I have just had too many problems mounting rails on new rifles.