Are you saying when the
Red battery feed was hooked to ammeter stud, there were no sparks when you went to connect at the battery?
and
When the black lead to the main splice was attached to the other ammeter stud, there were sparks when you went to connect the battery?
If both of those are true, then the short is downstream of the ammeter.
If the something in the ammeter was grounding out, you should have had sparks when just the red battery feed was connected.
You could snug up the other ammeter stud nut (without the wire attached) just to be sure.
PROBLEM SOLVED!! When I hooked up the extra ammeter I had, the problem went away, I didn't think these simple ammeters could go bad but that one did. Thanks everyone!