Mr Darnell very nicely sold me a .22 cal FC III. In concurrent communications he said he had a bunch of parts, from different suppliers, for a .30 cal FC III, Would I like him to make one up? I did and received both via SFRPM. So multiple months go by with me looking at Al flashing every where I shop as I can. None of it is correct.
I find a box of Hornady checks obtained with some reloading "stuff" and learn to seat them on my lyman 55 gr .224 bullets. This goes well. I only ruin 3 checks by dropping them upside down in my 450. I split the nose of about 10 bullets seating checks so those will have to be recovered.
One eve. I searched on line for Al roof flashing. I find a brand ive never heard of at Home Despot. I can't find any info on thickness. Finally I take an 8" wide roll ( the least expensive) to checkout. A very friendly clerk looks on H.D.'s data base and finds the thickness is 0.011. Perfect.
At home I use my Harbor Fright 12" shear/break to cut some strips. I screw a 7/16" bolt into the top of my classic cast and make a 1" tall split ring to fit around the top of the ram. These hold the FC III in place with the discharge end on top of the ram. The checks fall through the ram into the primer collection tube just like spent primers.
These seated as easily as the Hornady checks. Yahoo.
Then I experimented with doubled up soda can material. I should have done this first. It worked as well as the flashing. I've been making PB checks for several months before this and have lots of cut down soda cans.
Live and learn.