Barrel Chambering Without a Reamer?

07 November 2003, 06:19

Anyone cut a chamber in a barrel without a reamer? By that, I mean just cut a chamber on the lathe with a tool.

Seems like with some basic cases like a 45-70 (straight case, rimmed) that this would be a fairly straightforward task.

I have a wildcat idea I want to play with but don't want to mess around having custom reamers ground.

Sam B.
http://www.fireflyarms.com

07 November 2003, 07:18

Saeed

Sam,

Yes sir you can cut a chamber without a reamer, but I would imagine it not to be too easy.

All depends how good you are on the lathe, and how good your lathe is.

07 November 2003, 07:44

Bill M

Hi Sam,

This might help answer some of your questions?:
http://www.nookhill.com/ubb/ultimatebb.php?ubb=get_topic;f=5;t=002616#000019

Regards, Bill

07 November 2003, 07:49

<G.Malmborg>

SamB,

There you go, perfect example of archieved information. Do a search regarding "half round reamers" We had a discussion a while back on how to make one of a kind reamers for test jobs. making up a half round reamer would be a lot less frustrating than trying to cut a chamber using a boring bar and the lathes compound feed. Been there, done that. Successful? Yes, care to repeat it? No...

Good luck,

Malm

07 November 2003, 08:04

Bill M

Sam,

A Half-reamer may also suit your needs?:
http://www.nookhill.com/ubb/ultimatebb.php?ubb=get_topic;f=5;t=005367#000000

Then you don't have to mess with solid carbide boring-bars (to reduce deflection), CNC lathes, etc., that may be required for chamber boring with a single-point cutting tool.

Regards, Bill

07 November 2003, 15:07

John Ricks

Case Hardened Corn Cob Reamers. Shape the cob with sandpaper, then fire harden in the campfire.

On a more serious tone, I highly advise using a proper reamer for any chambering job, especially if the goal is a "Standard SAAMI Chamber" and the rifle may in the future fall in the hands of another person. Even Wildcats benefit from a real reamer. Chamber surface finish is very important, and dimensional tolerances are extremely important both for safety and ease of extraction.

Many years ago when I was sure I knew everything I worked in a well equipped tool and die shop with all the fancy lathes, mills and grinders. I made a chamber reamer, with flutes, the standard way. After this one time experience I learned to send money to a professional reamer grinder, it is a whole bunch cheaper and you get a better product.

What is your Wildcat? Chances are it has been done before.

07 November 2003, 15:14

vapodog

With all due respects friends, it's possible to bore a chamber instead of reaming it.

It's all in the way you hold your cards.

07 November 2003, 16:40

rembo

I have researched this just a bit.There is tooling avaliable,commonly referred to as "micro tooling" that will do this,within reason.Anything from .375 bore and up wouldn't be that hard(you can fit a bigger boring bar into the bore),depending,of course on how long the chamber is.A solid carbide bar combined with a good CNC machine(small chuck,high RPM and a very rigid spindle)and you could give it a try.Try it before I do...please.

07 November 2003, 17:04

triggerguard1

Having only ran a mere few thousand parts on CNC lathes, the answer is most definitely, YES.

Here would be your limitations:
1)diameter of neck(anything under .308 caliber is going to be extremely difficult.

2)Length of cartridge(any cartridge over .308 length is going to be nasty to hold tolerance.

3)Inspection and qualification of the machined surfaces.

About the best cartridges going for this kind of operation would be the WSM's or WSSM's.
Surface finishes and tolearances on those particular cartridges would rival any reamer in existence. The best scenario would be probably the .375 WSM.

Boring bars for doing this kind of work are pretty much off the shelf if you know where to look. There really not that special.
Solid carbide would be undoubtly in order as well as having through coolant capabilities as well.

Most likely you would rough the operation out with an endmill before tackling the finish op with the boring bar.

But, with all that said, it is more than feasible, and could produce quite desirable results. You just better figure on getting your own CNC before you start. This is not a job for the manual lathe, by any means.

07 November 2003, 17:44

<G.Malmborg>

quote:
Originally posted by John Ricks:

On a more serious tone, I highly advise using a proper reamer for any chambering job, especially if the goal is a "Standard SAAMI Chamber" and the rifle may in the future fall in the hands of another person. Even Wildcats benefit from a real reamer. Chamber surface finish is very important, and dimensional tolerances are extremely important both for safety and ease of extraction.

Many years ago when I was sure I knew everything...

Half reamers have been used by some pretty big boys in the gunsmithing business for many years. My first exposure to these half reamers were at P.O. Ackley's shop in SLC. This guy was certainly not known as a hack (my word). In the right hands, these produced excellent results. Since then I have made and used them myself for odd, "one of" jobs, mainly during my early years. Knowing what you're doing is half the struggle when using these. If used correctly, exceptional results are very possible.

Now, years later, having a collection of body, neck and throat reamers, to handle just about anything I would care to tackle is nice. But it is equally comforting to know, that should a "one of", wierd occasion arise, and I choose to accept it, I can take it head on without having to rely on someone else to provide me the necessary tooling to do the job.

My advise, don't limit yourself to only that which you can purchase. Be safe about it, be smart, think it through, and have fun...

Good luck,

Malm

[ 11-07-2003, 08:45: Message edited by: G.Malmborg ]

07 November 2003, 20:10

Brent Moffitt

I know a Gent that shoots 1000yd BR and he does his "own" chambers and dies on a CNC him and his brother have in their shop, a very expensive one. He said it's friggin scarry it cuts so damn FAST too! The last one was a 30, short mag length, but based on the 416 Rigby case.

08 November 2003, 04:22

John Ricks

Well, yes, anything can be done, but when you run the bottom line costs associated with making half reamers, trying to bore with a boring bar on a manual lathe, etc., it ain't cost effective IF one is making a living chambering barrels and building rifles. If anyone really wants to see it, I have a nice article written some 25 years ago about cutting chambers in a manual lathe with boring bars and dial indicators set up to measure what you are doing.

I would venture to guess few of us have the proper CNC lathe and the programming experience to bore chambers. If you do, then you are fortunate.

For one-off work, or something for the home project category, sure, have at it. But when safety is involved and once the rifle leaves your hands you have no idea of who uses it or what they will stuff in the chamber, the it is reamers made by a professional reamer grinder for me.

One key for me is repeatabiilty. I want the 416 Ultra chamber I put in a rifle today to be the same as the one I put in a rifle 5 years from now.

The rules change when one progresses out of hobby gun work to a business.

08 November 2003, 06:00

<G.Malmborg>

As I read the original question, no where do I see any reference to "hobby or business" much less anything regarding "repeatability". I see an uncomplicated, very simple question asking if a chamber like 45-70 can be cut without a reamer, and the straight, "No Bullshit" answer is "YES" period.

It wouldn't matter if a person were wanting to do an experimental project, requiring a specially dimensioned chamber, as a hobby, or as a professional development project, the answer is the same, "YES" it can be done.
[Smile]

Regards,

Malm

08 November 2003, 06:01

wallyw

quote:
Originally posted by John Ricks:
[QB]
For one-off work, or something for the home project category, sure, have at it. But when safety is involved and once the rifle leaves your hands you have no idea of who uses it or what they will stuff in the chamber, the it is reamers made by a professional reamer grinder for me.
QB]

What is inherently unsafe about cutting a chamber with a boring bar, half-reamer or any other method short of a "professionally" ground reamer?

08 November 2003, 06:04

triggerguard1

quote:
Originally posted by Brent Moffitt:
I know a Gent that shoots 1000yd BR and he does his "own" chambers and dies on a CNC him and his brother have in their shop, a very expensive one. He said it's friggin scarry it cuts so damn FAST too! The last one was a 30, short mag length, but based on the 416 Rigby case.

I would estimate with a conservative feedrate, intended for long tool life, you would be looking at about 1min to 1min30sec. to rough and finish your chamber. That of course, is just machine time. This does not include your setup time, which wouldn't really be that traumatic either. Needless to say, if you had several barrels of similiar caliber, you would be awfully fast at the process.

But, with all that said, I would still prefer to use a quality carbide reamer for the process in a CNC lathe. You'd probably be looking at about 45 sec. a pop doing it with that method.

08 November 2003, 06:23

Dutch

For completeness only, but there are a number of factories that hammer forge their barrels AND chambers at the same time. FWIW, Dutch.

08 November 2003, 06:39

SamB

Thanks for the insight folks. Seemed possible and I'm glad to hear it has been done successfully.

This is a one-off project for fun. A short .50 along the lines of a 500 Whisper, 50/110, etc. I don't doubt it has been done before, but as I said, it's just for fun.

Thanks again,

Sam B.
http://www.fireflyarms.com