Rim Trimming Tool

[Slo' Poke Pete]

Ok folks, please forgive my ignorance.  I've got a Cimarron/Uberti in .45-60 and although I've got some Jamison brass on the way I've got a ton of .45-70 brass I've acculated over the years and would like to be able to trim some down to use in the .45-60.  I've done considerable reloading but never trimmed the rim on a case before.  Is this possible to do without a lathe?  If so, what tool is used?

Many thanks.

Rob

[reloader4410]

My 45 colt R&D cylinder would'nt chamber scholfield brass, rim to big so I chucked up a wood dowel in a drill  & duct taped enough so the brass would fit then just touched it with a good file, worked great. hope this helps.

[Trailrider]

Howdy, Pard,
Oops! Sorry, I misread your inquiry.   Are you referring to trimming the outside diameter of the rim, or thinning it?

Trimming the outside diameter can be done by obtaining a metal lag screw that will fit inside the mouth of the case.  Probably a 3/8" diameter will work. You will need some sort of power drill or drill press that has a large enough chuck to accept the head of the lag screw.  You can then use a mill file to either reduce the diameter of the rim or thin the FRONT EDGE of the rim.  DO NOT THIN FROM THE BACK END OF THE RIM or you will reduce the depth of the primer pocket!

Of course, if you do get access to a lathe, it is quite simple to use an insert in the mouth of the case and a live center in the tailstock, inserted in the primer pocket.  Then use either the cutting tool or a mill file. 

Sorry not to have given the correct information.

[Grizzly Adams]

Check out this article by Kirk Durston.   Opens as a PDF.

http://www.leverguns.com/articles/1876.pdf

[Trailrider]

Check out this article by Kirk Durston.   Opens as a PDF.

http://www.leverguns.com/articles/1876.pdf

Oh, most definitely!    One word of caution on using IMR4198 without the filler... use a firm crimp and get a nice tight fit between the bullet and the case.  The purpose of a filler is to keep the powder back against the primer flash.  In a repeating rifle, the recoil of previous shots tends to send very light charges of powder toward the FRONT of the cartridge, away from the powder!  IMR 4198 is slow enough that you need to insure proper ignition.  If you get ANY hangfires go back to using the filler or go to a more bulky powder or a faster-burning powder.  The filler used by the author of the article was a 2-inch square of single-ply toilet tissue, poked just deep enough into the case (using the eraser end of a pencil or a 1/4-inch diameter wood dowel with the "poking" end rounded off)  to allow the bullet to start to be seated.  Let the bullet do the seating of the filler.  Do NOT compact the toilet tissue onto the powder charge.  If the idea of using a filler is not appealling, I'd recommend going to a slower powder like IMR3031, WITHOUT a filler.  IMR3031 will burn dirtier and leave some particles in the bore, but it isn't dangerous.
A chronograph isn't a necessity, but it is nice to have to check perfomance and consistancy.

Ride careful, Pard!

[Joe Lansing]

    Slo Poke Pete:
        Before you start thinning rims, check your rifle to see if this is necessary. Many '76s will take the 45-70 rim as is.....my Chappy
    does. Why bother if your rifle doesn't need it. You don't want to create a head space problem. If you can't easily close he action over     
    a 45-70 rim, then by all means trim away.

                                                                     J.L.             .

[Grizzly Adams]

    Slo Poke Pete:
        Before you start thinning rims, check your rifle to see if this is necessary. Many '76s will take the 45-70 rim as is.....my Chappy
    does. Why bother if your rifle doesn't need it. You don't want to create a head space problem. If you can't easily close he action over     
    a 45-70 rim, then by all means trim away.

                                                                     J.L.             .

+1   Very true!  May Cimarron/Uberti 76 was good to go with shortened 45-70 brass.