Repairing Bad Chamber jobs

[GSP7]

Recently picked up a rifle someone "tryed" to rechamber to 9.3x62 from 9.3x57. Well its a bad chamber job with some tool mark ring/ridges about midchamber mostly on one side of the chamber. They dont seem to be deep..?...and its very hard to see rings or tool marks, it just looks like a dark or rust spot, but I just fired 3 reloads in the rifle to see what the brass looks like and if it extracts the brass. The brass did extract easy and I can see the tool marks for sure on the brass.

Other than a last resort of setting the barrel back .833,one turn on this m98 mauser) Is trying to hone the chamber an option and how much is to much .002-.006 ???. I do reload and mostly just neck size and this isnt a target rifle just a hunting rifle

Thanks for any good gunsmith advice for options on cleaning up this chamber

Rick

 

[butchlambert]

Rick,
I think that you have the decimal point in the wrong place. It may take 2 threads and I think it would be good insurance to redo the chamber.
Butch

 

[sjk]

Your choices are few, depending on how bad and deep extraction wise the chamber is scoured with concentric rings etc
Otherwise:
Rechamber it to another cartridge that has the same bore dia but a larger case.

Set it back in one full turn and rechamber it to existing.

Insert the existing chamber and start from scratch.

If you can polish the rings out to your satisfaction and the extraction is easy, maybe you should approach it from this end first. It's the easiest solution if done correctly without eccentricity and extending headspace. If it ain't broke, don't fix it. LOL

 

[TRECustom]

Rick, 1 full turn on the Mauser should be .083". I'm pretty sure they are 12 tpi. The 9.3 x 62 probably has enough taper to clean up in one turn or maybe less if the chamber isn't wallowed out. If the barrel doesn't have sights or something else on it that requires clocking in again at 12 o'clock, the chamber might clean up with a 1/4 or 1/2 turn.

Good luck, Tom

 

[GSP7]

Yes its 12tpi. I ment .083. It has sights and barrel band.

What do you riflesmiths use to hone a chamber? I dont find a special tool from Brownells.

 

[butchlambert]

I measured a 9.3x62 cartridge this morning. It is .471 just in front of the extractor groove and .466 about .500 up. Not much taper. It depends on where the bad spot is. It may take more than 2 threads.
Butch

 

[GSP7]

Butch, it depends how deep the tool marks are. They arent very deep from what I can tell so far. Im going to try some full power loads soon as my new graf 9.3x62 brass gets here. Then get some cerrosafe and do a chamber cast. It might or might not clean up with a light hone. Last resort is set back.

I did a quicky and sized a few 3006 cases and shot 3 loads of 49gr imr 4895 with a 285gr prvi bullet,light load). The cases extracted easy but I can see some light ring marks/ridges on the brass

I am curious what devise others use to hone a chamber?

 

[butchlambert]

A cerrosafe mold will probably scrape off the excess when you punch it out of the chamber. Shoot a stiff load and measure the brass on the bad spot and close to it. Might give you a little better feel for your problem.
Butch