The Home Machinist!

Hello, i just joined the forum and have been reading thru some posts but had a question for you all that have made chamber reamers. Basically what size to you make them? i can find the case dimension information in reloading manuals but when it comes down to making the reamer i would think you make it a thousanth or two bigger on the diameters maybe even the lengths, would i program the radius any bigger? I will probably make them at work on the cncs and mill flutes at home in my mill. My first project is rebarreling and old mauser i have in a .25-06, and another in .22-250 and want to make my own reamers. i have made form tools and reamers at work before but always knew exactly what my finished dimention was to be. any advise is appreciated.

thanks
phil

SAAMI is a better source of dimensions than the reloading manuals. See the Table of Contents for rifle cartridges and click on the ones you want to see. There are both maximum cartridge and minimum chamber drawing for each standardized cartridge. I personally would go with the minimum chamber dimensions unless you have some specific reason to go larger. Larger will shorten the life of your brass assuming you are reloading and too much larger will become dangerous.

Personally I buy reamers as I don't have the proper machinery for making them although I understand your wish to make as much of the process yourself.

how do you deal with dimensional changes after heat treat without grinding? or are they small enough to not matter in this application?

Heat treat first, then grind. If you have a lathe, a tool post grinder is easy to make. I will post a photo of mine if needed.

Reamers have to be ground after heat treat, they warp and change dimensions when heat treated. And you cannot get the cutting edge reliefs in without a tool post grinder. Pretty easy once you have seen it done.

Dave Kiff's book of chamber prints has hundreds of standard and wildcat and tight benchrest reamer dimensions. Go to the Pacific Tool & Gauge website.

Find this book by Hoffman. He goes into great detail on making chamber reamers.

if you are only doing one off barrels/chambers consider using simple d shape reamers.

I make my own chambering reamers...Sometimes I grind a chambering reamer from a round HSS tool blank. Cut the flutes with a carbide endmill. Relieve the edge with dremel and then sharpen with diamond hone.. The picture shows .218 BEE chambering reamer I made last week, ground HSS with flutes cut with carbide endmill.....No heat treating required.

.I have to make a .44-40 chambering reamer in next week or so...This for chambers in cylinder of single action revolver I am building from barstock..And will have to make a second chambering reamer in same caliber but with different sized pilot for cutting chamber in Winchester mod 1873 rifle that I am also working on..This'd be an expensive hobby if you had to buy all this stuff.
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