Kirk,
Here’s what I’ve been doing to load 12 gauge light loads in 2 1/2" RST straight walled hulls for light 1/2 and 3/4 ounce loads. Actual weights are 0.50 and 0.72 ounces from my tweaked MEC charge bar.
I use the neon green Clay Buster CB6100-12 wad intended for one ounce loads. I use a 0.125" thick card wad in the bottom of the shot cup for my 1/2 ounce load. Nothing needed in the bottom of the shot cup for my 3/4 ounce.
In both cases, the petals are a little (1/16") higher than the shot volume. I have trimmed off a little of each petal before loading but I'm thinking that it is not necessary??
I use once plus fired RST 2 1/2" hulls and they look fine when finished, nice 6 point crimps, not dished or crushed.
I use a MEC Sizemaster for my loading and for the crimp start and final crimp stations, all that I did was use a 1/4" thick wood spacer at those stations to raise the hull to the 2 3/4" height. (In the pictures below, note that I have my MEC Sizemaster sitting in a low walled box to contain those in evitable lead shot spills.)
My load data:
½ ounce: RST 2 ½” hulls; Winchester 209 primer; 14.2 grains of Alliant Extra Lite powder (MEC #26 bushing); CB6100-12 wad; 0.125” card wad in bottom and ½ ounce lead shot.
3/4 ounce: RST 2 ½” hulls; Winchester 209 primer; 14.6 grains of IMR 700X powder (MEC #25 bushing); CB6100-12 wad; no card wad in bottom and 0.72 ounce lead shot.
Have shot both loads on the skeet and sporting clays field and they sound and feel great. Very satisfied.
I may send some test loads to Tom Armbrust but I don't think he does any testing in cold Illinois weather. I use basically the same recipe in loading standard 2 3/4” hulls and have had those tested by Tom Armbrust with the following results for ½ ounce loads with Win hulls, Win primers, 14 grains EL powder (MEC #26 powder bushing) average of 5100 psi at an average speed of 1367 fps. The ¾ ounce loads are from published 700X recipes and are around 6500 psi and 1250 fps.
I get my card wads from Craig Smith of Circle Fly Wads in PA and they cost about 1.5 cents each including postage per 1000.
Here's a thread from last June on a similar subject:
http://parkerguns.org/forums/showthread.php?t=16638
Bill Jolliff
