Many of you will find this humorous. I am the kind of “gunsmith” you guys like to ridicule. The kind you like to tell to stop doing gunsmith for himself and go find a real gunsmith. Sometimes I would have to agree with you...... 
I have no machining background. I flew USAF jets and now work in a corporation. I bought a nice new Taiwan built lathe (PM 1340GT) and mill (PM 833T) a year ago and jumped headfirst into all this. After having my lathe six months I chambered my first barrel, a fireforming barrel and it came out good. The next barrel was six months later when I decided the barrel I was shooting in LR BR just wasn’t competitive.
So I indicated in the new barrel, predrilled, bored, and the used a Mitituyo long reach indicator. The indicating took several hours over a couple days. I started with a drill bit just barely larger than the indicator body. The finish was so bad that by the time I had bored out a good finish, I wound up boring the hole out too much. So I parted it off and stared over, and predrilling has gone the way of the Dodo for me. Butch and Gordy notwithstanding..................
A couple days later I had the barrel re-indicated in, this time with the Interapid long reach. Threading was not going well, but I did the whole chamber job (BAT SV) anyway. I just didn’t like how the threads and tenon looked so I ordered another barrel.
Which the old barrel still in the lathe I turned off the threads and was determined that I would figure out how to make good threads and eliminate the lathe dial from jerking. I was told by my BR Smith friend to lower the threading cutter below center line, and that fixed it. I now have a Krieger 7.5 twist .237 4-groove barrel that will make a great 26.75" barrel for something..............
A couple days after the new barrel arrived, a 31 incher this time, I had it indicated in. I learned that I can push on the chuck and get .0002” movement. I called Matt of Precision Matthews and he said he said that was normal, and that he in fact had seen even more movement on heavier and higher end lathes. I also learned that when the barrel is centered the indicator will wobble around at about .0002”. I figured it just like shooting when the mirage is making the bull dance around and I aim for the center of the movement.
I was getting a nice finish on my tenon and it was cutting right in line with the cross slide movement as measured by a Mitituyo 1-2” digital mic. I was down to the last .009” and I made a cut just shy of .009”. Except when I measured it with the Mitituyo I said I didn’t make a cut. Well, the Mitituyo doesn’t lie so I cut again. I got the same measurement. That’s when I learned that the data hold button was easy to bump (who the hell would design it that way?). So I parted off the barrel and started again. And lectured myself--as ONLY a crusty old field grade officer can do--about how idiotic it was to not trust the lathe dials when measurements were confirming dial movement to well within .001" for the last 15 times I had checked..................
I indicated the barrel in again, and this time it only took an hour, which was a six-fold improvement from my earlier efforts. I used grizzly rods to get it close, then the Interapid to get it to zero.....and by that I mean the Interapid had movement within .0002" as best I could interpolate on a .0005" high quality indicator.
Things were going quite well this time. I had the cone within spec and with a good finish, the threads looked decent (even at 45 rpm), and I had .003 to .004" of gap with the action tightened on the barrel and the STD 6 BR go gauge inserted. I checked everything about 50 times then removed the barrel from the lathe, put it back in to crown in, the removed it again. As I was tightening the action to the barrel in the barrel vise, it went almost a 1/4 turn past where I did on the lathe. I went to bed.
I indicated the barrel in again. I had to cut the shoulder back, take a little off the cone, and deepen the chamber some. As I was pushing the reamer in the chamber, with a style floating reamer holder I'll not use again, it kissed the back of the chamber. CRAP!!! I just made my chamber slightly oversize. And I scratched it too. It took another .015" to clean up the scratch, and I obviously had to cut the shoulder back and trim the cone some more.
I was having a problem getting the action to make contact with the shoulder. I measured the tenon and it was at the minimum length, and I could see plenty of room left in the action for the barrel to screw in deeper. I thought and thought about it, and remembered that after cutting the cone that I had to clean up the threads so the action would start on the barrel threads. I wondered if the same thing could happen on the other end of the threads?
So I got out the 60 degree thread file and worked on the last couple threads immediately before the shoulder. Lo and behold that fixed it! I finally was able to complete everything. I discovered that by having my shoulder cutter at too much of an angle, I was collapsing the last thread before the shoulder. This time I really had it. Everything was within desired tolerances and I had excellent action to shoulder contact.
I was bothered by the oversize chamber but I decided to shoot it and see how bad it was. The brass comes out .001" larger in the butt than my fireforming barrel and the other barrel chambered with his reamer. Not optimum, but not a disaster either. I am a little concerned that brass life might be shorter than it should be.
I started load development very concerned if my hack gunsmithing had messed up this barrel. It actually seemed to shoot a little better than my previous barrel. The best load in excellent conditions gave me a 1/4" 5-shot group at 200 yds with a velocity ES of 6 fps. In subsequent short range testing that load only gave me 9/16" groups at 200, but it was in variable wind and the vertical was still about 1/4" and ES at 5 or 6.
Last weekend I took it to a 600 yd NBRSA match. I tweaked seating depth at 600 on Saturday and shot the match on Sunday, still wondering if I had messed up the barrel. I managed to take first for six target aggregate group size. It was windy and no one's groups were great, but given I shot as well as anyone else I am starting to think that maybe I didn't mess it up too badly.
Next barrel will be faster and easier with the 3,000 lessons I learned on this one.
The End.
I have no machining background. I flew USAF jets and now work in a corporation. I bought a nice new Taiwan built lathe (PM 1340GT) and mill (PM 833T) a year ago and jumped headfirst into all this. After having my lathe six months I chambered my first barrel, a fireforming barrel and it came out good. The next barrel was six months later when I decided the barrel I was shooting in LR BR just wasn’t competitive.
So I indicated in the new barrel, predrilled, bored, and the used a Mitituyo long reach indicator. The indicating took several hours over a couple days. I started with a drill bit just barely larger than the indicator body. The finish was so bad that by the time I had bored out a good finish, I wound up boring the hole out too much. So I parted it off and stared over, and predrilling has gone the way of the Dodo for me. Butch and Gordy notwithstanding..................
A couple days later I had the barrel re-indicated in, this time with the Interapid long reach. Threading was not going well, but I did the whole chamber job (BAT SV) anyway. I just didn’t like how the threads and tenon looked so I ordered another barrel.
Which the old barrel still in the lathe I turned off the threads and was determined that I would figure out how to make good threads and eliminate the lathe dial from jerking. I was told by my BR Smith friend to lower the threading cutter below center line, and that fixed it. I now have a Krieger 7.5 twist .237 4-groove barrel that will make a great 26.75" barrel for something..............
A couple days after the new barrel arrived, a 31 incher this time, I had it indicated in. I learned that I can push on the chuck and get .0002” movement. I called Matt of Precision Matthews and he said he said that was normal, and that he in fact had seen even more movement on heavier and higher end lathes. I also learned that when the barrel is centered the indicator will wobble around at about .0002”. I figured it just like shooting when the mirage is making the bull dance around and I aim for the center of the movement.
I was getting a nice finish on my tenon and it was cutting right in line with the cross slide movement as measured by a Mitituyo 1-2” digital mic. I was down to the last .009” and I made a cut just shy of .009”. Except when I measured it with the Mitituyo I said I didn’t make a cut. Well, the Mitituyo doesn’t lie so I cut again. I got the same measurement. That’s when I learned that the data hold button was easy to bump (who the hell would design it that way?). So I parted off the barrel and started again. And lectured myself--as ONLY a crusty old field grade officer can do--about how idiotic it was to not trust the lathe dials when measurements were confirming dial movement to well within .001" for the last 15 times I had checked..................
I indicated the barrel in again, and this time it only took an hour, which was a six-fold improvement from my earlier efforts. I used grizzly rods to get it close, then the Interapid to get it to zero.....and by that I mean the Interapid had movement within .0002" as best I could interpolate on a .0005" high quality indicator.
Things were going quite well this time. I had the cone within spec and with a good finish, the threads looked decent (even at 45 rpm), and I had .003 to .004" of gap with the action tightened on the barrel and the STD 6 BR go gauge inserted. I checked everything about 50 times then removed the barrel from the lathe, put it back in to crown in, the removed it again. As I was tightening the action to the barrel in the barrel vise, it went almost a 1/4 turn past where I did on the lathe. I went to bed.
I indicated the barrel in again. I had to cut the shoulder back, take a little off the cone, and deepen the chamber some. As I was pushing the reamer in the chamber, with a style floating reamer holder I'll not use again, it kissed the back of the chamber. CRAP!!! I just made my chamber slightly oversize. And I scratched it too. It took another .015" to clean up the scratch, and I obviously had to cut the shoulder back and trim the cone some more.
I was having a problem getting the action to make contact with the shoulder. I measured the tenon and it was at the minimum length, and I could see plenty of room left in the action for the barrel to screw in deeper. I thought and thought about it, and remembered that after cutting the cone that I had to clean up the threads so the action would start on the barrel threads. I wondered if the same thing could happen on the other end of the threads?
So I got out the 60 degree thread file and worked on the last couple threads immediately before the shoulder. Lo and behold that fixed it! I finally was able to complete everything. I discovered that by having my shoulder cutter at too much of an angle, I was collapsing the last thread before the shoulder. This time I really had it. Everything was within desired tolerances and I had excellent action to shoulder contact.
I was bothered by the oversize chamber but I decided to shoot it and see how bad it was. The brass comes out .001" larger in the butt than my fireforming barrel and the other barrel chambered with his reamer. Not optimum, but not a disaster either. I am a little concerned that brass life might be shorter than it should be.
I started load development very concerned if my hack gunsmithing had messed up this barrel. It actually seemed to shoot a little better than my previous barrel. The best load in excellent conditions gave me a 1/4" 5-shot group at 200 yds with a velocity ES of 6 fps. In subsequent short range testing that load only gave me 9/16" groups at 200, but it was in variable wind and the vertical was still about 1/4" and ES at 5 or 6.
Last weekend I took it to a 600 yd NBRSA match. I tweaked seating depth at 600 on Saturday and shot the match on Sunday, still wondering if I had messed up the barrel. I managed to take first for six target aggregate group size. It was windy and no one's groups were great, but given I shot as well as anyone else I am starting to think that maybe I didn't mess it up too badly.
Next barrel will be faster and easier with the 3,000 lessons I learned on this one.
The End.
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