I am an amateur gun tinkerer and I have cut three chambers. One was in a shot out 7 Mag barrel to get my feet wet. One was in a LW-50 barrel that I chambered to 7mm-08 and the other is a 264 Win Mag in a CM LW barrel. I borrowed the reamers from a fellow gun tinkerer so I don't know the exact history on the reamers. They are PTG reamers from Midway and both have only cut 3 or 4 chambers.

Both of the barrels I chambered have taken 50 rounds or more with thorough cleaning after each shooting session to break in. Accuracy was so-so in both and both fouled badly at first. Both are now shooting well, one inch or better groups at 100, which is about my ability with a hunting rifle, and neither fouls badly now.

I suspect the break in is mostly due to the tool marks left in the throat by the reamer. The reamers I used were used so that may well be a factor. Both did most of their cutting on one flute which doesn't seem right. Anyway the chambers I am getting are clearly not acceptable to somebody building match rifles.

What do the professionals do to minimize tool marks in the throat? Do you get better quality reamers than the ones sold at Midway? Or do you hone the cutting edges on the reamer to get it to cut cleaner? Or is it different cutting oils or something else or all of the above?

My chamber reamers are a conglomeration of Mansojn, JGS, PT&G and Clymer. I throat separately using mainly JGS custom live pilot throaters, mainly because I've had these for years, and I use Mobil Met Omega as my cutting oil of choice. All machining operations leave tool marks. Whether the reamer has 1 or 100 chambers under it's belt you have to inspect and dress, if necessary, the cutting edge each time you use it. I use a tri-cornered ceramic stone that I will run the length of the cutting face prior to using. This knocks off left over crap that can severely damage an otherwise great throat. The make up of the barrel steel has a lot to do with finish also. I keep my hand in constant contact with the reamer so that I can feel if there is any trouble brewing. It takes time and experience to work out the kinks and sometimes you have to put rounds down range to get them to shoot. Mostly it's practice, practice, practice!

Thanks Westpac. Inspecting and dressing the edges makes sense as I normally do that with lathe bits before I use them. Also the material. I rethreaded a SS Remington barrel that cut much nicer than the LW50. I forgot(I am recovering from a concussion and CRS!) another Winchester CM barrel I rethreaded and rechambered a couple weeks ago. It seemed to cut nicer than the LW CM barrel.

I also wonder if I ordered a custom tight neck match reamer if the person grinding it would be a little more careful setting up the machinery? Maybe a little better QC than normal for an off the shelf higher production reamer?

I guess it isn't just me. I just ran across an article by Wayne Van Zwoll where he ordered a custom 30-06 from a reputable maker using a Lilja barrel. He said the rifle has a habit of tossing fliers that he expects to go away with break in.

BR shooters go through a lot of barrels. They seem to foul initially as do hunting barrels. It appears that more machining burrs are in the throat area. A lot of the guys work the throat with JB and the fouling goes away quicker.
Butch

I use 00000 steel wool.
Regards, Joe

Marc, I would not say you have a reamer problem. A bad reamer has a dimensional problem, or leaves a poor finish. A single flute cutting should have nothing to do with the throat finish.

I would be inclined to blame it on your BBL.

If you can find someone with an endoscope, it will tell you a lot about where the problem is.

Ben, both barrels seem to be fine now. I have a Douglas 30 caliber barrel I want to put on my 30-06 and I would like to minimize the break in. It sounds like some break in is unavoidable, even for benchrest barrels. It just took longer than I expected and am looking for ways to reduce it.

I have not seen 00000 steel wool locally. I have some 0000. I have JB though I seldom use it any more since Wipe Out came out. I will try that on the Douglas barrel.

quote:

Originally posted by Marc:
I have not seen 00000 steel wool locally. I have some 0000. I have JB though I seldom use it any more since Wipe Out came out. I will try that on the Douglas barrel.

Just get yourself some used 0000 steel wool.

quote:

Originally posted by Marc:
Ben, both barrels seem to be fine now. I have a Douglas 30 caliber barrel I want to put on my 30-06 and I would like to minimize the break in. It sounds like some break in is unavoidable, even for benchrest barrels. It just took longer than I expected and am looking for ways to reduce it.

I have not seen 00000 steel wool locally. I have some 0000. I have JB though I seldom use it any more since Wipe Out came out. I will try that on the Douglas barrel.

I find the 416 bbls break in a lot easier, another reason I try to talk people into using them.