I'm going to make up some 8.15X46R cases from 30-30 brass. I haven't done this before, although I've re-loaded for years. What is the best/simplest way to shorten the cases?  I have a trimmer, but it seems like a lot of cranking to remove all that brass.  I did a test round and used a razor saw, which worked, but this also was labor intensive. Any suggestions?
One thing I did learn on the test case; just resizing in a 8.15X46R die didn't work. I ran it thru a 32-40 die after and it dropped in perfectly.  No doubt it will need fire forming, but at least it chambered.
Mike.

Forster makes a set-up for trimming on a drill press if you have one, they are simple to use and as fast as anything I am aware of. I would think they still make them. I use mine all the time and have for a long time to trim wildcat and forming and trimming cases formed from a parent case as in your situation. I have also used a small trim saw from harbor freight that works well, but you need to clean up the cut. I use a wilson case holder to hold the case while cutting. I use it when there is quite a lot to remove. With the forster I believe the may make a cutter that chamfers the mouth of the case also. Not sure.

I use a RCBS case trimmer, took the crank handle and screw out ,replaced it with a hex bit from a case prep machine that had the same thread size and used a small cordless hand drill for power. Trims a 1/4 to 3/8 off of a case in no time.

Thanks, Guys!
Went to HF this morning and they had the cut-off saw "in-stock"
Better yet, they let me use an expired "20% off" coupon 
I'm thinking of making up a case holder from a piece of wood that I can mount in the vice and it will hold the case just where I want it.
Thanks again!
Mike.

I've been thinking about it and the next time I have to make a jig to hold the case being cut I might do it a little differently. I would start with a strong piece of wood like a 2x2 piece of oak. I would cut it to a length just a little shorter than from the inside of the rim to the length I wanted to end up with. I would drill a hole through from the front the diameter of the neck and no larger. From the rear I would drill a head diameter hole just far enough in to be able to slip a case in up to its rim. Then I would cut it longways so that one half left exactly one half of the trough depth. The width of the piece with the trough would need to be adjusted to center on the saw axis. The depth of the wood under the trough might have to be adjusted to provide clearance for the travel of the saw. Once the trough is held in the vise, adjusted so the saw is cutting at the proper length and square to the end of the case it would be time for the cutting part. Drop a case in the trough and run it in up to the rim and chop!

Good suggestions.  I'm thinking of using a short section of hard wood and boring a hole about neck diameter then opening one end to accept the base diameter so the rim stops at the edge.  The chop saw will let me adjust the position so I just cut what I need.
I know this isn't very much shortening but my trimmer for this cartridge is manual.  I have a Gracy set for 308/30-06 but I doubt they make a holder for this cartridge.  Anyways, new tools and gismos are more phun 
Thanks again for your input!
Mike.

Most of the calibres that I shoot are obsolete, so I do a lot of re-forming and shortening brass.
Assuming the case is tapered: take a piece of scrap steel bar about 1/16" to 3/32" larger diameter than the base diameter of the case. Turn it to the required case length less the rim thickness. Drill it through to the neck diameter of the required case. Drill through to the base diameter, stopping about 1/4" short of the end. With a hacksaw, cut a slot along the length, creating a split sleeve. 
The brass to be shortened is entered into the sleeve which is then chucked up in the lathe. A knife edge tool is then used to cut off the surplus length.
Once the sleeve is made, this method is quite fast.
Fred

I have the same Lyman kit. Great---but not for taking 3/8" off as I had to do last week.
Fred