polished chamber

G

Gene DeLoney

New member
I had a conversation today with a fellow shooter who is having trouble with heavy bolt lift after the cases are fireformed..........not the click but heavy at the beginning lift.
He mentioned that he polished his chamber to a chrome like finish which I feel is the possible cause of the problem.
I think this was discussed here before and and someone said to finish the chamber with 340 grit paper to give the case something to grab on to.
I leave my chamber just as the reamer cuts it but as this gun is already chambered he would just rough up the walls.
Question is whether 340 grit is proper or something courser or finer.......
Gene
 
Gene, I have always found that if reamed properly, the finish that the reamer leaves is ideal for that combination of giving the case something to "grip", and still allow easy extraction.

You should avoid a polished finish as your post indicated.

Another thing is to be sure the cases are clean, free of any sizing wax, oil, etc.
 
What kind of neck clearance does he have? I've found with 3 thou. clearance things get a lot nicer.

Joe Salt
 
I do a quick cross hatching with 320 grit sandpaper wrapped around the smooth end of a chucking reamer with the lathe running around 1800 rpm.
 
Gene, I wouldn't use that. Those things are made for removing metal. A quick 5 to 10 second polish with 320 grit sandpaper does nothing more than just change the appearance of the chamber. It won't change dimensions unless over done. It looks like you are wanting to rough up the chamber without using a lathe. If you don't have a lathe, I'd take it to someone that does. It will take longer to take the barrel off than to hit the chamber with 320 grit sandpaper. I used to polish with 600 grit sandpaper a long time ago and went to 320 just because of hard bolt lift with too smooth of a chamber.
 
Last edited:
Mike Bryant said:
Gene, I wouldn't use that. Those things are made for removing metal. A quick 5 to 10 second polish with 320 grit sandpaper does nothing more than just change the appearance of the chamber. It won't change dimensions unless over done. It looks like you are wanting to rough up the chamber without using a lathe. If you don't have a lathe, I'd take it to someone that does. It will take longer to take the barrel off than to hit the chamber with 320 grit sandpaper. I used to polish with 600 grit sandpaper a long time ago and went to 320 just because of hard bolt lift with too smooth of a chamber.
Click to expand...

Mike,
The fellow that is having this hard bolt lift problem does have a lathe and does his own barrels. Since he has already polished the chamber to a chrome finish, just putting the barrel back in the lathe and using the 320 paper treatment should do it.
I recently started using a new Henrickson reamer that cuts an extremely smooth surface and have been getting bolt click after only 2-3 firings on new cases with moderate loads. I think I will try the 320 paper on it and see if it helps.
Thanks,Gene
 
It depends on where the

"click" is. Measure up .200 from the case head on a fired unsized case. Size the case and check at .200 again.
I like to see at least .0007 reduction on a sized case.
To get an accurate measurement take a piece of round stock and bore a hole .200 deep set the case in that. and measure with a blade mic.
Alot of times the click is from not sizing the base enough.

Richard Brensing
 
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