I need to chamber a barrel blank for 9mm luger. I know I can rent a reamer but I have the capability to bore it on a cnc prototrac lathe. My problem now is finding geometry for the chamber.

Im curious though if anyone here has done it?

Log on to Clymer Reamer for chamber dimensions.
Good luck!

That part of the site seems to be down.

Many gunsmiths bore the chamber, short, and then finish with a reamer. I'm speaking of bottleneck rifle chambers. I don't see why you couldn't program a cnc machine to bore a simple chamber like the 9mm Parabellum. I'm sure you could bore the lead also.

The SAAMI spec on 9mm Luger chamber diameter is .3950 to .3990" at the rear and .745 -.010" from the breach face is the mouth of the case with diameter .3800 to .3840".
The throat is 2 degrees with diameter .3540" at .8133" forward of the breech face.

I have made a few chambers without a reamer, and I am still willing to do some chamber work without a reamer, but my personal rule is, "Never make a chamber without a reamer becuase you are too cheap to buy the reamer. There must be some compelling other reason."

You don't need a lathe for a 9mm chamber reaming. Just put the reamer in a hand held chuck, put some cutting oil on the reamer, a few twists of the wrist, and it should headspace.

Manson 9mm reamers are $60 at Brownells or at Manson.

http://www.mansonreamers.com/pricelist.htm

http://www.brownells.com/aspx/NS/store/ProductDetail.as...L+CHAMBERING+REAMERS

http://www.brownells.com/aspx/NS/store/ProductDetail.as...26+THROATING+REAMERS

quote:

Originally posted by tnekkcc:

You don't need a lathe for a 9mm chamber reaming. Just put the reamer in a hand held chuck, put some cutting oil on the reamer, a few twists of the wrist, and it should headspace.

Staying with this theme, why not use an electric drill?

However, if you want to end up with a chamber that is fairly concentric and somewhat snug, use a lathe...

Get off the soap box-this is a pistol chamber! This is not a 1/4 moa bench gun job. Handturned reaming, with lots of cutting oil, and brush out the chips every 4-5 turns, and it will do de job, mon.

It is quite possible to single-point lathe-cut a chamber for a straight-cased round such as the 9 m/m or.45 ACP.

It is also quite possible to ream a chamber with or without a lathe.

However, in my opinion:

1. You really need to work out in advance how you are going to cut the chamber taper, to do it both well and easily, if you are going to do it without a reamer and if the case of the cartridge is designed to function with any taper to it, as the 9 m/m Luger is. That can be as simple as determining the correct angle and using your compound to feed the cutting tool for a short chamber.

2. I sure wouldn't want to try to bore a tapered chamber with a cutting tool other than a reamer, if I didn't plan to use a lathe.

3. Though it is not likely important that your chamber meet SAAMI specs, if for some reason you want to completely duplicate the chamber in another gun, later, that's a lot harder to do without a reamer, unless you have a CNC lathe and save your program.

While it is possible to cobble a working chamber with just as little as a set of twist drill bits, a hand drill, and a grinder, the farther you get from half-arsed methods, the happier you will likely be in the long run.

9mm is really a very easy chamber to ream with hand power. One can short bore it and then finish ream ... but it is just as easy to use a reamer for the whole thing. I would not do this with any cartridge larger than a "straight wall" pistol cartridge like 9x19, 9x21, Super, 9x23, or 40 S&W ... but it works for those.

Last one I did was for an AR-15 on a Shilen bbl. Went well, and the little fella shot clover leaves at 25 yards on semi ;>

quote:

Originally posted by Lanny from NY:
Get off the soap box-this is a pistol chamber! This is not a 1/4 moa bench gun job. Handturned reaming, with lots of cutting oil, and brush out the chips every 4-5 turns, and it will do de job, mon.

Then so will using an electric drill motor!

Should be reasonably easy to do on the 9mm, but on most bottleneck rifle cartriges the dia. to length ratio of the boring bar would be getting very interesting. In the old days we figured 1 to7 would be max with solid carbide shanks. Lots of chatter without lots of precautions.

Thanks for the responsed guys.

I'll be using a prototrac CNC lathe. I'll have to drum up a small enough boring bar to do the job but it will be carbide tipped and should cut easily.

All I need to do is pick up my tool by maching something internally, measure ut and plug in the numbers on my readout and then chuck up the barrel. Then I can use a gauge pin in the bore to indicate concentric.

Then all I need to do is plug in my geometry for the chamber. Programing and all should take no more than 30 minutes.

I can leave the chamber a little small and then polish. The only problem is I dont have any chamber gauges. I wonder If I could use a live round to check fit? This will be a Mac-11 barrel.

Thanks for all the help guys.

I remember reading a post by John Ricks about boring straight wall cases without a reamer.

Terry

quote:

Originally posted by johnnymceldoo:

I'll be using a prototrac CNC lathe. I'll have to drum up a small enough boring bar to do the job but it will be carbide tipped and should cut easily.

Circle Machine makes some great little boring bars that use interchangeable carbide inserts. When boring with a small flexible bar, I usually set the carbide insert a couple of thousandths above center to keep the boring bar from grabbing and digging in.

quote:

The only problem is I dont have any chamber gauges. I wonder If I could use a live round to check fit?

The round headspaces off the mouth of the chamber, so for setting the chambers depth, a factory cartridge should work just fine. I would probably go for an end clearance of no more than .003.

I was looking at "Gunsmiths tips and Projects"
Wollf Publishing co.
There is a detailed description of how to bore a chamber on a lathe.
It looks like you have to be damn good to pull it off. I'd try somthing like a sizing die first.
Good luck!

How you propose will work, but I would just MAKE the reamer first! Then you have a reamer for either future projects or ebay, and if you don't have a headspace guage you do not have to worry about losing indexing when you remove the barrel.

Not to say you cannot do it your way, but I would even rather just regrind a drill bit to make a reamer than try doing it one shot with a boring bar.

Get OFF the elecric drill cracks! You can get off axis is one second with a drill, but a hand turned reamer requires you to be ham-handed for a much longer time. Of course, I'm never surprised anymore when it comes to stupidity about doing the most simple tasks. The schools have all decided we don't need dangerous classes like metalworking or woodworking about 20 years ago. Makes sense-everything is made in China, and if it don't work throw it out, buy another.