Chamber Reamers

[BORGY76]

Are reamers the popular choice because most chambering jobs are done on a manual lathe? Seems like a inserted boring bar would be a better route, with multiple passes and minimal code.

 

[Walt Krafft]

I have actually done some on a cnc lathe. The problem is the boring bar is very long for its length. A quick rule is you can go 4 times the diameter of the bar before starting to have issues. A reamer is also more consistent chamber to chamber than a boring bar will be.

 

[BORGY76]

Makes sense. I was just thinking of tool wear and taper. I've been toying with doing a barrel. I would have to make some spider adjusters.

 

[WSnyder]

A guy that went by the name of 4Mesh (Phil something) did a bunch of his LR BR chambers with CNC and boring bar. He was a pretty ingenious and successful guy.

I believe Straight Shot gunsmithing (True Bore chuck system) was also working on it (CNC & boring bar) at one point.

 

[gunsandgunsmithing]

As others have said, easier said than done with a relatively long hole and a small boring bar, cnc or not. If I were gonna do this, I'd likely indicate everything same as now, pre-bore then ream with a zero freebore reamer and only cut the throat with the boring bar, from the same setup. In the end, I think a reamer is the best tool for this particular job, though. FWIW, the reamers are all now, AFAIK, made on cnc grinders. If the reamer has a good finish with proper relief angles, it's gonna be hard to beat it with any kind of boring bar, even in a big hole. I think this is more of a solution looking for a problem than a practical way to chamber bbls.

 

[butchlambert]

Probably someone like Butch or Josh is better suited to answer your question, but I'll take a stab at answering it.

When you use a boring bar you need to open up the chamber in small increments. As such the machinist needs to measure and keep track of the inside diameter as they cut. You also have the neck and shoulder to deal with. It would be difficult to cut that with a boring bar. Most machines are accurate enough these days to hold within a .001" tolerance, so the dials keep good track of where you are at. However, the final cut can often be off, and some machinists will take an extra "spring pass" as the boring bars tend to have at least some spring when coupled with the tool post/holder, carriage, lead screw, et al.

The reamer is a set fixed size, and most machinists will only use the reamer for the last pass. So you really do need both, boring bars and the reamer so that your chamber is the closest to the final dimension. The reamer is the most accurate. You could use only a boring bar and my guess is it will work fine, because firearms do not require the accuracy. You might be able to imagine that we have evolved since muskets and we are more accurate today. Also consider that precision shooters have been trying to diagnose this process for possibly as long as luthiers have been trying to understand why the Stradivarius violins sounded so great.

One other point about the reamer as it relates to allowing a more accurate chamber in shape and/or consistency, most gunsmiths tend to use them as little as possible to keep them as close to original spec as possible. Any time you use it you risk the chance you may damage it. Many lathes have the power to cause bad juju when you make a mistake. Reamers last if used properly, but many people get impatient and that dulls them quicker. Lots of factors including machines style of chambering (headstock/centers), skill, power, et al...

With all that said, I don't want you think I know what I'm talking about, but I have a number of reamers and most machinists use reamers after drilling so that they can have the most accurate holes as well, for more info you could probably search online or look in the Machinery's Handbook. Maybe Butch or Josh can explain it better than me. I'm not a professional gunsmith, nor am I a professional machinist.

Pretty much the way it is.

 

[Dusty Stevens]

Reamers last longer than youll use em and they make perfect chambers.

 

[Carl S]

U will not get the deflection with a reamer as you can with a boring bar.a chip on your boring bar tip,undetected after a series of cuts and your chamber is shot..its possible.indicate barrel muzzle and throat pre bore and ream,can't go wrong.chamber zero run out or a couple of tenths.why complicate things it a proven method.

 

[LC Tikka]

Barrels are hammer forged, why not forge the chamber at same time.

 

[Walt Krafft]

Barrels are hammer forged, why not forge the chamber at same time.

Some do. But it is still just a hammer forged barrel.

 

[Carl S]

Hammer forged barrels arnt as good as a custom cut rifled barrel.i can't see as one can hammer forge a chamber as good as a
reamed chamber is when set up and done correctly..I might be wrong.

 

[gunsandgunsmithing]

Hammer forged barrels arnt as good as a custom cut rifled barrel.i can't see as one can hammer forge a chamber as good as a
reamed chamber is when set up and done correctly..I might be wrong.

I don't know enough about the hammer forged barrel process to form an opinion of much value but in theory, the bbl, chamber and throat could be forged in a single setup and be as near perfect as anything could be. But, I'm sure it's not as simple as that and it surely does impart a lot of stress. fwiw

 

[Carl S]

I don't know enough about the hammer forged barrel process to form an opinion of much value but in theory, the bbl, chamber and throat could be forged in a single setup and be as near perfect as anything could be. But, I'm sure it's not as simple as that and it surely does impart a lot of stress. fwiw

Yes stress kills accuracy as we no.we want barrel,action and stock-bedding stress free.it kills humans to,no good for nothing.stress free life is what we want...can't beat it.

 

[SKWERLZ]

Hammer forged barrels arnt as good as a custom cut rifled barrel.i can't see as one can hammer forge a chamber as good as a
reamed chamber is when set up and done correctly..I might be wrong.

Maybe not for accuracy but hammer forged barrels are quite good for long live and durability.

 

[Carl S]

Maybe not for accuracy but hammer forged barrels are quite good for long live and durability.

I've seen and owned some very accurate factory built rifles.i had a Remington vssf .223 years ago which I sold to a friend.super accurate.all I did to that rifle was rebed the action,screwcut and recrown the barrel,tune and set the trigger .there was a factory sporter class in our 100yd benchrest comps.he would shoot 5shot groups with moving backers in the .1's on a regular basis...seriously. .2's were common.aggs in the.3's .2's on one occasion.beating full blown 6ppc heavy varmint benchrest rifles regularly and really upsetting the real serious guys.52grn berger match bullet.25grns N133.205 gold medal primers.lapua brass.leupold 25x scope.he still owns it..a real gem.

 

[BORGY76]

Pacific Tool & guage a good company for reamers?

 

[TrxR]

Pacific Tool & guage a good company for reamers?

I would suggest Manson or JGS.

 

[Walt Krafft]

JGS has been the best for me.

 

[Tommie]

I have a set of dies made via boring bar.
Meh.

 

[LVLAaron]

Pacific Tool & guage a good company for reamers?

Yes, if you like cutting with one flute.