Typical home made al gc's are made with roof flashing. What you want to do is measure the gc shank on the cast bullet.

35cal (38spl/357/etc) ='s .344"
41cal ='s .395"

10/1000th's thick material will work for both calibers.

.344 + .010 + .010 ='s .364" for a .358" bullet
.395 + .010 + .010 ='s .415" for a .410" bullet

You want 5/1000th's to 6/1000th's of crimp to the gc. That ='s 3/1000th's per side to have the gc lock/bite into the shank of the bullet to hold it in place.

If you get too thick of a material it will actually deform the gc shank enough to affect accuracy. To thin of a material and the gc will not crimp/hold onto the gc shank.

I was making my gc's in the traditional style (right). When I started pc'ing (powder coating) bullets it made the gc shank larger so I redesigned my gc forming die to flare the gc's mouth a little larger. I also rounded the base a little more for better bullet seating in the case. (left)


I've made my own gc makers for years. 2 Thompson designed bullets. Left is a 200gr hp for the 44cal's. Right is a 150gr hp for the 35cal's.


I also made gc makers for the 30cal's & 22cal's.

The gc makers pictured above use an arbor press to make them. I cut al roof flashing into strips and dip them into a full pot of hot lead for casting to anneal them. Then I turn them into gc's. 1 pull of the handle ='s 1 gc.