Chambering steps for hobbyists

[Tod Hendricks]

This is intended for the hobbyists/competitor types who repeatably chamber barrels for the same actions on a manual lathe, which is what I do. I have a few Borden BRMXD’s and I compete in Fclass, I can and do switch my barrels randomly between any of my actions.

Originally my steps for chambering were, dial in, tenon, thread, cone, chamber.

For a while now I’ve switched to dial in and then chamber. This allows me to confirm an acceptable chamber prior to any other work or time invested, and more importantly ease of setting the headspace exactly the same every time. To do this I ream so the go gauge is past flush, .010” to .030” doesn’t matter just past flush of the barrel end. Then touch off go gauge with facing tool and cut face of barrel. For my BRMXD’s I cut my tenon length from go gauge to shoulder at .8986”. This is where I like my headspace set. So with my turning tool I touch off go gauge, zero dro, advance to .8986” zero dro. Then cut tenon and shoulder to zero. It’s very precisely repeatable.

I cut .010” short of shoulder until final pass on tenon. I use a flexible plastic pusher in tailstock to push on go gauge when touching off.

For me and my system it seems like the best way.

Tod

 

[Jonnyofalltrades]

Good procedure. My only question is, how do you touch off your facing tool on the go gauge if the go gauge is below flush? Do you rough a little bit off first?

 

[Tod Hendricks]

Good procedure. My only question is, how do you touch off your facing tool on the go gauge if the go gauge is below flush? Do you rough a little bit off first?

My facing tool can touch in there pretty far, I can only cut about .015” max with it. I could post a pic if you wanted. It’s probably more of a turning tool, it’s a larger Warner hss triangle cutter. I don’t worry to much about the face as most gets cut away as the cone.

 

[Walt Krafft]

I do the same only never touch a cutting tool to a gage. Depth mic and indicators are the tools to use. Chamber deep, face off, set indicator to 0, depth mic, move to your number and finish face.

 

[paperpuncher]

The last barrel I did I actually stumbled onto this exact process. I will be doing them this way going forward. I have been learning to utilize my dro more often I think it helps me achieve better consistency.

 

[Tod Hendricks]

I do the same only never touch a cutting tool to a gage. Depth mic and indicators are the tools to use. Chamber deep, face off, set indicator to 0, depth mic, move to your number and finish face.

You are correct, I know better but get lazy I guess.

 

[Will Henry]

I find it every bit as easy to set chamber depth when reaming as by facing. I've been doing the reaming as the last step (except for cutting and extractor slot, if required) for the last fifty years. It works for me. WH

 

[LVLAaron]

I assume you don't clock/time your barrels?

 

[Henryrifle]

I assume you don't clock/time your barrels?

I wondered the same thing but if Tod says he doesn't then I am going to stop.

Hank

 

[Tod Hendricks]

I assume you don't clock/time your barrels?

I used to time every one, then I started just timing the ones that had significant muzzle runout. Now I hardly ever time them, I still measure it and log it. Honestly I could not correlate it to improving or degrading performance. This relates to 1.25” straight barrels.

 

[Henryrifle]

Thank you @Tod Hendricks! Looking forward to trying it your way but realizing that it puts even more pressure on the lathe operator not to screw up the threads!

Thank you,
Hank

 

[Kings X]

Pretty much the way I do it. Except I thread after I have trimmed excess off the chamber. Put center in chamber and thread. Last step is to cut shoulder to achieve correct headspace.
If it is a Remington type counterbore, I do that when I trim. If it is a cone, I do that after I headspace.

 

[jackieschmidt]

Strictly from a machinist point of view, I always establish the best chamber possible in the barrel and then work everything off of it.

First, I indicate the barrel exactly where I want it, then rough out the heavy cutting. I then do the final indicating, and finish the chamber. Next comes finishing the tenon, set the headspace, finish the cone or what ever he particular bolt nose requires.

I do this because in my opinion, the most difficult aspect of chambering a barrel is establishing the very best chamber possible exactly where you want it.

By the way. I do not “clock” my barrels because they always point straight. This is proven when I change barrels. Just last Sunday, I installed a ne 30BR barrel on my “club match” rifle, and the barrel I installed printed within 1 1/2 inches at 100 yards of the barrel I took off.

The need for this “clocking” thing is a product of what has become called “the Gordy Method” of setting up barrels to chamber. If the muzzle end ID exibits runbout, logic dictates that it should at least be pointed up.

 

[Jonnyofalltrades]

Strictly from a machinist point of view, I always establish the best chamber possible in the barrel and then work everything off of it.

First, I indicate the barrel exactly where I want it, then rough out the heavy cutting. I then do the final indicating, and finish the chamber. Next comes finishing the tenon, set the headspace, finish the cone or what ever he particular bolt nose requires.

I do this because in my opinion, the most difficult aspect of chambering a barrel is establishing the very best chamber possible exactly where you want it.

By the way. I do not “clock” my barrels because they always point straight. This is proven when I change barrels. Just last Sunday, I installed a ne 30BR barrel on my “club match” rifle, and the barrel I installed printed within 1 1/2 inches at 100 yards of the barrel I took off.

The need for this “clocking” thing is a product of what has become called “the Gordy Method” of setting up barrels to chamber. If the muzzle end ID exibits runbout, logic dictates that it should at least be pointed up.

But so far the only reason for "clocking" is logic, right? I've never heard of anyone actually testing this theory with centerfire, although rimfire guys have beat it to death.

 

[LVLAaron]

"Needing" to clock is an artifact of having your chamber aligned with the bore.

But so far the only reason for "clocking" is logic, right? I've never heard of anyone actually testing this theory with centerfire, although rimfire guys have beat it to death.

I'll admit I haven't tested it, but I would *think* a 32 inch barrel clocked 90 or 270 degrees (right or left) could cause weird rifle tracking. But the other voice in my head argues that every shot will be the same so it doesn't matter.

If nothing else, I clock'em so they are aesthetically correct in a stock.

 

[Bob3700]

I clock my bbls. This keeps the amount of windage on my rear sight ( irons) closely centered up. U have seen the crooked bbls. If the high spot of the muzzle is at 90 or 270 degrees u can eat up a lot of windage adjustment centering up.
probably not an issue at short ranges but at 600 n beyond it matters to me.

 

[WSnyder]

I've never heard of anyone actually testing this theory with centerfire

Gene Beggs tested it (SRBR gun) quite a lot years ago in his tunnel. He came up with a differentialy threaded bushing to index the barrel at different points. It was a Panda or Viper action I believe. If I recall he felt indexing down at 6 was maybe better. I don’t remember his final conclusions. The differentialy threaded bushing setup (the small tenon to be more precise) had issues with full pressure loads in that the base of the case would swell (clickers) much more than with a standard diameter tenon. Much was discussed and learned beyond the indexing. Stiller got involved and did the hoop strength calculations.

Here’s one old post. There were many others on BRC back then.

Testing the barrel indexing system

This evening in the tunnel, I tested the latest prototype of the barrel indexing system. The rifle is one of my 'Ultralite' stocked sporters chambered in 6 Beggs with a .269 neck. The barrel tenon on this rifle is the smallest diameter I have tested at .800 before threading. I, as well as...

benchrest.com

 

[Jesswil61]

This is a subject that I have bounced around for some time. I have chambered using the "Gordy" method and have seen some pretty bad results in runout on the muzzle end, when chamber base and throat are running true that had to be reeled in. Someone please correct my thought, if this does not make sense. If you dial a barrel to 0 run out on the muzzle end and at the chamber throat and then boar your rough chamber with a boring bar to this axis then keep this zero for the final chamber cut with the reamer, does this not negate any need of clocking?

 

[LVLAaron]

If you dial a barrel to 0 run out on the muzzle end and at the chamber throat and then boar your rough chamber with a boring bar to this axis then keep this zero for the final chamber cut with the reamer, does this not negate any need of clocking?

Correct. But you lose angular alignment between your bore and chamber.

 

[Jonnyofalltrades]

Correct. But you lose angular alignment between your bore and chamber.

Which, depending on the barrel, may be nothing, or quite substantial.

Gene Beggs tested it (SRBR gun) quite a lot years ago in his tunnel. He came up with a differentialy threaded bushing to index the barrel at different points. It was a Panda or Viper action I believe. If I recall he felt indexing down at 6 was maybe better. I don’t remember his final conclusions. The differentialy threaded bushing setup (the small tenon to be more precise) had issues with full pressure loads in that the base of the case would swell (clickers) much more than with a standard diameter tenon. Much was discussed and learned beyond the indexing. Stiller got involved and did the hoop strength calculations.

Here’s one old post. There were many others on BRC back then.

Testing the barrel indexing system

This evening in the tunnel, I tested the latest prototype of the barrel indexing system. The rifle is one of my 'Ultralite' stocked sporters chambered in 6 Beggs with a .269 neck. The barrel tenon on this rifle is the smallest diameter I have tested at .800 before threading. I, as well as...

benchrest.com

Thanks for the referral! I'll have to check it out.