Need help with chamber pre-drill and bore.

[dennisinaz]

just don't do what I did




I did my first chamber today with the pre-bore method. I made paint mark on the 29/64th so I would know where to stop. That went fine. I then set up a taper with my compound and started cleaning up the hole. That went fine too until I went to take my last spring pass. I must have bumped the crossfeed handle because as I started feeding the boring bar in I realized that it was taking off more than it should have. I stopped and hoped that it could clean up with the reamer..

It didn't- the last .08 or so is oversize and looks like heck. The rest of the chamber is mirror smooth. Be careful not to take to much out!!!

Not sure the best way to check progress when boring a tapered hole. Live and learn I guess.

 

[pdhntr]

I did my first chamber today with the pre-bore method. I made paint mark on the 29/64th so I would know where to stop. That went fine. I then set up a taper with my compound and started cleaning up the hole. That went fine too until I went to take my last spring pass. I must have bumped the crossfeed handle because as I started feeding the boring bar in I realized that it was taking off more than it should have. I stopped and hoped that it could clean up with the reamer..

It didn't- the last .08 or so is oversize and looks like heck. The rest of the chamber is mirror smooth. Be careful not to take to much out!!!

Not sure the best way to check progress when boring a tapered hole. Live and learn I guess.

I can understand your anger.

Not everything went as well as the chamber on mine. I got the goofy idea to cut the threads left to right with the bit upside down. I have done a couple this way and they came out great, but I did something wrong (still don't know) and I made a mess.

Luckily I caught it quickly enough to recut and they came out OK.

Shot a test round through it last evening and it looks very good. In the process of inletting it into the stock now.

Jim

 

[pdhntr]

Thanks JonathanK.

I will make a copy of that and maybe use it on the next barrel.

Jim

 

[Clark]

This is the chart I made in 2010 when I was drilling, boring, and reaming in baby steps into a Lothar Walther barrel black to make a 7mmRemMag chamber.

My objective was to always have a certain about of pilot engaged with the bore, when reaming.

I should say that I was pushing the reamer the same way I have for 10 years, since I read something Mike Bryant wrote about how to do it on Yahoo gunsmthing group.