Merle does recommend the Federal Bulk Pak (plated), and specifically recommends against the Remington Golden Bullet.
Merle makes his own 50 rd drums out of another Black Dog drum, using his own production steel rear spine, a part so beautifully machined that I would like to buy one just to mount on a board as a piece of art. But, Merle will not sell them except attached to the drum.
Unless Merle has changed his specs, he was making two versions of the spine/drum, due to differences in grip frame slots -one for Hurleys, and one for "real" Thompsons (couldn't help myself).
The difference is only a few thousandths, but it was enough to prevent inserting the WH drum in a Colt.
Remember, his .22 drums mount the same as a stick mag; they don't use the horizontal drum slots at all, so can be used on M1s.
Edited by mnshooter, 05 January 2017 - 09:58 PM.