An old machinist friend of mine once said: "If you want to be a successful gun builder, don't turn down any work."
I've been working on expanding my customer base to those outside of the M14 and M1 Garand world and I've been working on other skills that appeal to the long range bolt crowd. One of those skills is being able to custom install a contoured barrel blank onto a bolt action rifle.
One of my customers has asked me to install two Proof Research barrels onto Remington CSR barrel extensions. He knows I've never done this before and is willing to wait while I train myself to do this kind of work.
Over the last year, I've bought all kinds of tooling, including carbide turning/facing tools and bits as well as carbide boring bars and inserts and external/internal carbide threading and grooving tools. I spent a lot of time getting my lathe in order a couple of weeks ago in preparation for this work. Here's the thread I posted on my results.
https://www.hobby-machinist.co...hews-pm1236t.110289/
At the end of the day, I was able to get my lathe aligned to within 0.0004" over the span of a 15 inch cut. So over the span of 15 inches, my lathe will cut a steel bar to within less than half a thousandth of taper. I got some advice from Frank at Bartlein barrels and he said my setup was more than adequate to do everything I can on that lathe.
He was gracious enough to send me some out of spec barrel blanks to practice barrel threading on. After three attempts to cut threads, I finally got it! My first attempt was foiled by a stupid mistake. Instead of cutting 16 TPI, I set to my lathe to cut 18 TPI. The threads were beautiful, but the wrong pitch! I practiced my second attempt on a cutoff M14 heavy barrel section and made a couple of goofs with my cross slide drifting off target and an error engaging the half-nut which bothched some of the threads. I was still able to produce a thread which allowed the extension to easily thread on, but the threads are way too small and there's a lot of slop.
After making those goofs, I formulated a plan and cut off the section of the Bartlein barrel with the wrong thread pitch and started over. At 1 AM last night I had nearly got it. I still wasn't able to thread the barrel extension on because the threads weren't cut deep enough yet.
In this picture was a take-off CSR barrel, the Bartlein barrel that I was working on and the cutoff barrel section from the M14.
I realigned the barrel into the lathe this afternoon and managed to pick up the threads with the thread cutting insert. I gauged the threads with a 3-wire thread gauge set and cut until they matched the thread diameter of the take-off barrel. I was now able to thread the insert on about a turn before it bound up, so I chased the threads a few times and was finally able to thread the extension on by hand all the way.
Here are the threads after the final cut and cleanup...
Barrel extension fully screwed on hand tight...
The bolt head had enough clearance to insert and rotate locked
Training barrel and take-off barrel.
Anyway, the next step will be muzzle threading to 5/8-24.
Thanks for looking!
Tony.
I've been working on expanding my customer base to those outside of the M14 and M1 Garand world and I've been working on other skills that appeal to the long range bolt crowd. One of those skills is being able to custom install a contoured barrel blank onto a bolt action rifle.
One of my customers has asked me to install two Proof Research barrels onto Remington CSR barrel extensions. He knows I've never done this before and is willing to wait while I train myself to do this kind of work.
Over the last year, I've bought all kinds of tooling, including carbide turning/facing tools and bits as well as carbide boring bars and inserts and external/internal carbide threading and grooving tools. I spent a lot of time getting my lathe in order a couple of weeks ago in preparation for this work. Here's the thread I posted on my results.
https://www.hobby-machinist.co...hews-pm1236t.110289/
At the end of the day, I was able to get my lathe aligned to within 0.0004" over the span of a 15 inch cut. So over the span of 15 inches, my lathe will cut a steel bar to within less than half a thousandth of taper. I got some advice from Frank at Bartlein barrels and he said my setup was more than adequate to do everything I can on that lathe.
He was gracious enough to send me some out of spec barrel blanks to practice barrel threading on. After three attempts to cut threads, I finally got it! My first attempt was foiled by a stupid mistake. Instead of cutting 16 TPI, I set to my lathe to cut 18 TPI. The threads were beautiful, but the wrong pitch! I practiced my second attempt on a cutoff M14 heavy barrel section and made a couple of goofs with my cross slide drifting off target and an error engaging the half-nut which bothched some of the threads. I was still able to produce a thread which allowed the extension to easily thread on, but the threads are way too small and there's a lot of slop.
After making those goofs, I formulated a plan and cut off the section of the Bartlein barrel with the wrong thread pitch and started over. At 1 AM last night I had nearly got it. I still wasn't able to thread the barrel extension on because the threads weren't cut deep enough yet.
In this picture was a take-off CSR barrel, the Bartlein barrel that I was working on and the cutoff barrel section from the M14.
I realigned the barrel into the lathe this afternoon and managed to pick up the threads with the thread cutting insert. I gauged the threads with a 3-wire thread gauge set and cut until they matched the thread diameter of the take-off barrel. I was now able to thread the insert on about a turn before it bound up, so I chased the threads a few times and was finally able to thread the extension on by hand all the way.
Here are the threads after the final cut and cleanup...
Barrel extension fully screwed on hand tight...
The bolt head had enough clearance to insert and rotate locked
Training barrel and take-off barrel.
Anyway, the next step will be muzzle threading to 5/8-24.
Thanks for looking!
Tony.
