I recently bought a RCBS accessory base plate; however my press (RCBS JR3) will not fit any of the holes. I am considering drilling and tapping the plate so that the press will fit. Has anyone ever tried this and if so how did it work.

sorry, MikeG, about the double post

No problem. Good luck finding an answer to your question.

I have not done it but I see no reason not to. Just find a spot that clears all the other holes and drill away.
Can you get one hole to line up correctly?

Yes, I think I will be able to.

Yes, I think I will be able to.


Great, then you only have to drill and tap one hole.

Hello everybody,
I am new here.
I have done it, to use Redding accessories (powder dispenser stand and trimer), well no transplants reject so far.
But you need to be careful. The plate is made of some kind of alloy, and if you look under the plate there is extra alloy material around where the holes are to lengthen the threads so they won't strip.
Like Oneshotman says, find a hole thats already there to use next drill and tap a new hole, the new hole will secure the press but don't torque it as much as the built in hole or it will strip. Hope I am making sense.
Regards.

. . . there is extra alloy material around where the holes are to lengthen the threads so they won't strip. . . the new hole will secure the press but don't torque it as much as the built in hole or it will strip. . .

FoxTrot,

Welcome to the forum. Thank you for contributing your experience. I haven't looked at one of those plates close up, but from what you say, it sounds like the new hole would be an ideal place to use a washer and nut for reinforcement?

The plate is made of some kind of alloy, and if you look under the plate there is extra alloy material around where the holes are to lengthen the threads so they won't strip.
My initial thought is to mount the press directly to the bench and use the accessory plate for accessories only, eg. powder measure mount, trimmer, priming tool, etc. Haven't seen this so don't know if it was ever intended for mounting a press.

Thank you Unclenick for the welcome.
The picture explains better than I can, the tip of the pencil points to one of the holes I made, so you can see the difference in cast aluminium material thickness.
RCBS says the plate is designed for the Rock Chucker Press and other accessories, if I were to drill and tapp a hole for a different press, I would follow your suggestion and secure the bolt with washer and nut.
Regards