Lines in chamber...Chatter or Hardened spot??

[JonathanK]

I recently cut a 6ppc chamber, screwed it on and shot it only to find that my brass had lines on the neck, the shoulder and part of the body close to the shoulder. The lines look just like the reamer going verticle, and were bad enough on the neck that it wouldnt seal and carbon went all the way to the shoulder. I set it back .030 and it looks a lot better but I can still see the lines on the shoulder just barely. I never felt the reamer chatter but I think I ran in to a hard spot in the steel. As I was running the bit in (roughing) I felt a spot where it was hard to cut. The bit stuck and I wound up breaking the tips on it. This barrel is a rechamber that I cut about an inch and a half in front of the original chamber. Any ideas or info would be great.
Thanks
Jonathan K

 

[Richard]

Take a piece of

wax paper and put over your reamer. It will feed a little stiff but it will usually take care of the problem. Just cut a little slit in the paper for the pilot to go through and have enough paper to cover around 3/4 of the reamer.

Richard

 

[JonathanK]

wax paper and put over your reamer. It will feed a little stiff but it will usually take care of the problem. Just cut a little slit in the paper for the pilot to go through and have enough paper to cover around 3/4 of the reamer.

Richard

OK Thanks, Im gonna try the wax paper. I was thinking I would set it back .050 this time, do y'all think that is enough?

 

[JerrySharrett]

OK Thanks, Im gonna try the wax paper. I was thinking I would set it back .050 this time, do y'all think that is enough?

Sounds like you have a lathe design/bearing adjustment or reamer setup problem. Part of the setup problem may be caused by the size reamer plot you are using.

 

[Jim Kobe]

Or...you have chatter. Sounds like it to me. You need to set it back at least the length of the neck area to eliminate all the chatter, Then... try the wax paper.

 

[JonathanK]

Thanks for the help...I was able to get rid of it by finding the correct size pilot and cutting the length of the neck....Lesson learned!

 

[JerrySharrett]

Thanks for the help...I was able to get rid of it by finding the correct size pilot and cutting the length of the neck....Lesson learned!

That is why you need reamers with replaceable bushings. Some of the old benchrest gunsmiths took pride in not even using a bushing but it was still a crap-shoot to cut a chamber that was perfectly on center with the bore. Same with chatter. Most of the old heavy American iron wasn't as subject to chatter as these lawn-mower quality lathes today though. Nor did they try to run high RPM when cutting the chamber.