They may have been this one has some 45 Colts in the back half .
That would make sense if it were for 100 each 410s ,you could 200 in a 30 cal can , probably even 3" .
Honestly I never even gave it a thought that it might have been a 410 tray . It always had 25-,30-06' or 22-250 in it but only for the 50 yr or so .

No wonder the guy on FB thought I was trolling ........ that'll probably make them easier to find and cheaper too .
It doesn't solve for the 45-70 but a 28ga tray might if they are for a 30 cal vs 50 cal can .