I have access to a Thomas & Betts TBM-5S compression lug crimper. It is a diamond crimper for alum or copper compression lugs. Can I use this to crimp tinned copper lugs on 4 AWG wire? For 4 AWG is says to use the gray die.
If you really want to know how good the crimp is, cut a cross section of one and examine how compressed the copper strands are. They should look almost like they got welded, without air gaps.