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Chambering/Barrel Work Needed

hepburnman

Aluminum
Joined
Feb 20, 2013
Location
NJ
I have checked over my lathe and have come to the conclusion that it is just not accurate enough for the chamber work that I was hoping to do so I would now like to solicit responses from others for doing my barrel work. I would like hear from gunsmiths willing to do this work, or hearing from anyone that has had good results from a particular gunsmith, with work on bench-rest competition barrels. I prefer the method of indicating the throat-area of the bore and also pre-drilling/boring prior to reaming. I would appreciate a PM from gunsmiths or anyone that can recommend a gunsmith to me that they have had good results with that use these methods. Thanks so much.
 
I have some side-to-side play when pushing on my chuck and the ram of my tail stock slews down and to one side when extended.
 
Applying about 20-30 lbs of force to the side of my chuck I can get about 0.0005" or a little more of deflection. Indicating along the top of my tail stock quill with it fully extended there's a 0.0025" change from the top to the back where it enters the tail stock. It appears almost like the backend of the tailstock is lifted slightly. With the quill fully retracted though, and indicting around a dead center I get less than 0.0005" TIR with the headstock spindle (these measurements were all made with a 0.001" DI).
 
a floating holder and you'll be fine... they say that Pope of Pope barrels that are so highly prized worked on some very very crude equipment, but that may be merely an internet rumor...
 
a floating holder and you'll be fine... they say that Pope of Pope barrels that are so highly prized worked on some very very crude equipment, but that may be merely an internet rumor...

Heard the same about P.O. Ackley. . If you know your machine you can overcome most wear problems. I would not call that any issue at all. Remember, everything will be determined by the pilot on the cutter. You Must have enough flexibility to allow the pilot to align with the bore.
 
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I took apart my tail stock where I removed the lower portion from the upper portion and found some dried out grease here (this is a 1940s-vintage SB Heavy 10" - ways were scraped by a previous owner however). After cleaning things up and reassembling (the square dove-tail here is also a very tight into its groove). I have just about gotten rid of the any dipping of the quill. It is basically level now. However, I am finding that the center of the quill is 0.0015" lower than the spindle. I am unable to accurately indicate the I.D. of the quill because of some wear on the inside taper. I have been using an M2 stem for a drill chuck and indicating on the smaller tapered diameter end where the chuck would fit on. I am unsure if the M2 stem is centering the same each time and this is difficult to determine because the smaller end of the stem is also tapered. I guess I could possibly shim up the tail stock by placing a shim between the two portions.
 
I took apart my tail stock where I removed the lower portion from the upper portion and found some dried out grease here (this is a 1940s-vintage SB Heavy 10" - ways were scraped by a previous owner however). After cleaning things up and reassembling (the square dove-tail here is also a very tight into its groove). I have just about gotten rid of the any dipping of the quill. It is basically level now. However, I am finding that the center of the quill is 0.0015" lower than the spindle. I am unable to accurately indicate the I.D. of the quill because of some wear on the inside taper. I have been using an M2 stem for a drill chuck and indicating on the smaller tapered diameter end where the chuck would fit on. I am unsure if the M2 stem is centering the same each time and this is difficult to determine because the smaller end of the stem is also tapered. I guess I could possibly shim up the tail stock by placing a shim between the two portions.

I think you are getting overly concerned about things that will not affect the accuracy of your chamber. I would not be concerned about .0005" of spindle deflection. If you plan to drill and prebore as you have outlined in your first post and you use a floating reamer holder/pusher the condition or alignment (within reason) of the tailstock will not be an issue. It is very common for tailstock alignment to change slightly as the quill is extended. In addition to the quill positiion the torque on the nut or lever that secures the tailstck will influence the tailstock postion as will the tailstock quill lock. Just some things to consider.
 
Hep I am not suggesting that you shouldnt try to get things as perfect as you can, but I do think that there is a point of diminishing returns. Here is a video that might help to illustrate that allignment to a couple tenths isnt the last word in building an accurate, I think it was part of the reason that the fellow made the video. He shows that the barrel is running out about .003" and chambers with a floating holder, the rifle shot very well. Again, before I get flamed Im not suggesting that you shouldnt try to get things dialed in as best you can, just that the effort should be weighed against the potential gains.

Chambering in the steady part 2 - YouTube
 
I guess the computer ate my reply. All I care about is good headstock bearings. What else matters for chambering? I don't care about a misaligned or loose tailstock. I chamber in the headstock with a cathead on both sides. I indicate first with Deltronic pins, rough drill, I use a small bodied 513-504 Mitutoyo .0001 indicator with a short probe. I have a couple Interapid indicators with long probes, but I think they flex and jump when indicating the throat area lands and grooves. After the predrill, I reindicate at the throat and taper bore the chamber. I want my reamer to follow a hole bored to be coaxial with the indicated throat, not following a possible wandering bore. Pictured below is my pusher that the tailstock pushes, but doesn't influence the reamers direction.
wswly8.jpg
 
Butch- I also would be chambering (if I can work up the courage!) through the spindle but with a four jaw chuck and a cathead at the other end. Chambering though for a .40-65 case the Mitutoyo DI looks like it would not have enough reach for me. I would need a reach of at least 2.5" so maybe the Interapid is my only option? I think I understand how your reamer pusher works. Is this of your own make (how would one obtain one?)? I guess too you dont see any appreciable issue of the side-handle influencing how the the reamer centers/cuts?

While I do not feel too uncomfortable with the tasks of indicating and even chambering, pre-drilling and boring (and how deep to ream) do appear to be an area that will require a lot of caution and thought about how deep to drill and also where in the bore to finish boring the taper. Any screw ups here would be tough to correct or may even scrap the barrel.

Thinking about this and that my case length is ~2.3" long my longest straight taper area starts from ~1.63" into the bore, where the I.D here is ~.430, to about 0.200" into the bore where the I.D. here is ~.490". I think I should end my boring at the 1.63" dimension rather than any further into the bore because my 0.5" long neck area is a very slight taper and over-boring here would be very easy. Also, concerning pre-drilling I think I would only drill 0.200" deep with a drill of about .480" diameter. Does this all sound about right? I would have to rig up an in-line DI to help determine tool-run in accurately. For how deep to ream I guess I could maybe just repeatedly insert a case and ream deeper until the face of the case is flush with the end of the barrel (I am using the same reamer as another rifle so I have fire-formed brass that will fit this new chamber)?

Thanks for the help and encouragement!
 
I guess that you can reach as far in as you can. Bores aren't as bad as some think. Everything is a compromise. I drill approx. .050 less than finish chamber base and .100 short of the shoulder if any. It is up to you to make your calculations. Taper bore to .050 short of finish dimension. Ream to finish dimension.
 
Hepburnman, if ya don't mind me sayin' so, I'm gonna suggest that you try some of this stuff out, get you hands and lathe covered in chips, and make a conscious effort to get past the obsession with perfection.

Perfect is the enemy of good, IIRC. Voltaire? Maybe.

By obsessing over all the minor details, you are building a great bloody stack of reasons not to move forward.

Dig out a chunk of barrel stock and a reamer and have at it. Do a chamber, figure out if it would work, cut it off and do it again.
I figure you will learn a lot more from that than you ever will from chasing dimensional perfection around in circles with an indicator on your lathe.

Cheers
Trev
 
Hell. The first barrel I chambered was a .308 going on a Vz24. I did that by hand and it shot great. At the time I was working where I could do government jobs, but no obvious gun parts, so I ground my reamer pilot at work to a very close fit, and did the chambering at home with a T handle.
 
trevi- Thanks for the encouragement. I plan to do just that. Since I have only made one threading attempt, and crappy at that, I will certainly get some old barrels or even bar stock and at least get in some cutting the tenon and threading experience. I have made some further tweaks to my lathe and refined my indicating techniques and I have now found that my tail stock quill to be no more than 0.001" high. With the quill fully extended it dips by less than 0.0005"! I am convinced now to give chambering a go. I need to next get a 0.0001" DI for indicating the throat and also something to give a bit of float to the reamer. I like something like the Bald Eagle type because it is simple, and being simple this may reduce issues with binding. I make this work further I will also pre-drill and also bore the chamber to the reamers taper prior to actually reaming. Now, for that barrel practice, anyone have a .40-cal SS barrel that is basically scrap or can be had for a low sum?! :-)
 
trevi- Thanks for the encouragement. I plan to do just that. Since I have only made one threading attempt, and crappy at that, I will certainly get some old barrels or even bar stock and at least get in some cutting the tenon and threading experience. I have made some further tweaks to my lathe and refined my indicating techniques and I have now found that my tail stock quill to be no more than 0.001" high. With the quill fully extended it dips by less than 0.0005"! I am convinced now to give chambering a go. I need to next get a 0.0001" DI for indicating the throat and also something to give a bit of float to the reamer. I like something like the Bald Eagle type because it is simple, and being simple this may reduce issues with binding. I make this work further I will also pre-drill and also bore the chamber to the reamers taper prior to actually reaming. Now, for that barrel practice, anyone have a .40-cal SS barrel that is basically scrap or can be had for a low sum?! :-)

Uhh...Nope. You need to get away from the theoretical, and get some dirt on yer hands and git some chips made. Reading about it is NOT the same as learning how to do it.

Obsessing over tools you think you need is stopping you from making progress.

Seriously. Get a couple bars of hex 12L14 and do some thread cutting. Forget the chambering, simply thread the end of the bar so it fits the action.

Too much theory, not enough hands-on! :) The gains in confidence that will come from the experience, will serve you far better than the obsession with minor details that are quite frankly, past your skill level to see the difference from.

A stick of 12L14 (leaded, free machining, mild steel) is pretty cheap and increases the odds of success way the heck over the use of crappy mild steel from rebar or any other source.
Brass works too. If you have some.

Once you figure out your technique on the 12L14, try it on some old barrel stock.

Honestly, I strongly suspect that any gunsmith that you 'interviewed' about his methods , and subjected to a line of questions about the how and why that you wanted your barrel done differently than what has been working for him, is like as not going to find a reason to send you off to somewhere else. Anywhere else!

If you are not going to do the work, the pick a guy with a good rep, tell him what you want to have done and for what purpose (chamber, caliber or alternately 'with this reamer', BPCR), and let the man do what he's good at.
The less time you spend talking to him, the more time he has to get on with his work day, eh?

You are getting very very far ahead of yourself, if you wish to chamber like the big boys, without first learning to get the rest of the basics down first. Waddya gonna do if you finally cut the 'perfect' chamber and botch the threading? Or vise versa? It's all part of the process, and it can all fall apart anywhere along the way from start to finish, eh.

Y'know. Just sayin'. :)


Cheers
Trev
 
Trev- Thanks again for the advice - 12L14 steel will be the first to practice on. I will also need to practice next on SS to be sure my technique does not result in work hardening before the process is finished.
 








 
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