Misbehaving Sporterized Mauser 98 (chamber?)

[Ed Ames]

The problem child today is a commercially sporterized '98 Mauser in 30-06. The company that sporterized it (GSA) has been dead for 30 years...

I gave it a general going over and nothing looked particularly wrong. Headspace was good. It didn't have any brass transfered onto the magazine follower or anywhere else, nor any particular signs of normal use...I nave no idea how often it was fired but I'm guessing "rarely if ever". I cleaned it, including brushing and swabbing the chamber. There was basically nothing to clean. The bore was shiney bright and, at least on the muzzle end, still blued.

So I fired it. No problem. It wasn't sighted in properly but it hit the paper nicely. Felt like a 30-06. Sounded like a 30-06.

Problem was, extraction was a real bear... the cartridge didn't want to come out at all. Once I got the bolt up it wasn't so hard to pull back, but getting the bolt up took some strength. Not quite "hammer time" but definitely not the easy snick-snick I'm used to.

No overpressure signs on the primer. I measured the case and every dimension was below max for a 30-06 by a few tho at least. The outside of the case was "printed" (for lack of a better term) with the shape of the chamber... and the printing wasn't smooth. There were shallow scratches or grooves around the circumference of the case. Rings around the neck, rings around the rest of the case... they stop near the head obviously.

I looked back into the chamber with a light and a jaundiced eye and I can see the matching scratches in the chamber. It looks like the chamber was gouged out with a rough reamer and never finished properly.

So, what's the most reasonable approach to fixing this? Set the barrel back and re-headspace with a finishing reamer? Just polish off the high spots since it is within tolerances? Get an Ackley improved or some equivalent reamer and re-chamber to something else altogether?

I have a 7mm rem mag short-chambered barrel boxed up in a closet.. OTOH that would leave me with a basically new 30-06 barrel in the closet.

 

[mete]

Polishing the chamber may open it up to the point you wouldn't want to reload the case . I would start polishing the chamber until I got a reasonable extraction and leave it at that. The best way of course would be to set back the barrel and rechamber.

 

[Jim K]

I agree. I would try 600 or 1000 grit paper on a split dowel rod in an electric drill. Go very easy, moving the paper in and out for a only couple of seconds the first time, then a bit more if needed.

The rough chamber is the reason for the hard extraction. The reason it affects bolt lift is that the 98 Mauser (like other bolt rifles) has something called primary extraction, in which the leverage of the bolt handle is used to start the case moving out of the chamber. You can see this if you watch the bolt move back as you raise the handle. By the time the case has moved partway out, it is no longer in contact with the chamber walls, thanks to the tapered case, and can then extract easily.

Jim

 

[Ed Ames]

Thanks guys, I appreciate it. I have a selection of sandpaper down to 2500 ... I'll give that a try.

Is this an area where I could use cerrosafe to check my progress or am I better off bringing my "sanding setup" to the range and polish 2 seconds/clean/fire/repeat until it extracts smoothly? Bring a micrometer along and mike the cases to make sure I don't take anything too far? Or is that overthinking it?

 

[s&w 24]

The best way to polish the chamber is to take a '06 case and ream out the primer pocket and connect a length of welding rod to the primer pocket. You can either solder on or tap and thread each part to stick it all together then use differing grades of valve grinding compound untill you have the desired finish. Make shure you use a variable speed drill with a very low end, you can't put metal back on only take it off.

 

[Borg]

LOL,, don't use the cerro safe at all,, you'll never get it out unless you heat it up,, doesen't shrink,,, at all
Borg

 

[Ed Ames]

But I thought cerrosafe shrunk for the first half hour and then started to expand again? Hmm... lemme look it up... # 30 minutes dimensions are -.0009" per inch... or about -.00027" ... LOL, 'nuff said.

So much for an excuse to use that toy.

 

[GaryK]

I had a sporterized Mauser that had a similar problem. It turned out to be roughness in the cutout in the bolt that the part that cocked the firing pin rode on when the bolt handle was lifted. I corrected it by lightly polishing the contact surface. It works smoothly now.