Re: Proper steel type for plates?
Many grades of stainless are "work hardening." That is, the more you cause it stress the more fine the grain structure becomes and the harder the material. You can see this when you bend a wire coathanger. The coat hanger bends in one spot but when you try to unbend it it bends in a different spot because the first spot became harder.
I have seen knurling rolls which are used for putting knurling on a shaft get ruined when the knurl was put on a stainless shaft and then the machinist took a second pass to deepen the knurl. The stainless surface hardened and when the second pass was made the knurling wheels became flat and worthless.
If you have a chunk of stainless I would reccomend an experiment.
On one side smack the surface with a ball peen hammer all over the surface a time or two. (Wear your ear cups). This should have the same effect as case hardening that side. Then go and shoot both sides at the same distance with the same load and see if the plate dimples are the same or less. as the un stressed side.
Also a note on T1 plate.
Forum member "Dave in Idaho" told me that he had a 12"diameter 1/2" thick T1 plate that withstood all rounds except one. The only round to go throught the T1 like crickets through a goose was out of a .220 swift.
I am currently sipping the last of a gin and tonic before turning in for the night so I dont remember the exact loading but I will try to find out and post it tomorrow. ERRR, Later today. Dang it's late.
GRAVITY. It's not just a good idea. It's the LAW!