We tested our ‘hammer’ type 6-awg crimper. It was my, personal, first time using it, and I only made the one test crimp using an average 2lb hammer, without any Thor-like strength or speed. Though the connector was quite warm after I crimped it.
Apologies for terrible cell phone pictures… 
Crimper:$32ish from McMaster
http://i.imgur.com/DA8xXQB.jpg (linked due to image limit)
Bolted it to a piece of 8020.
http://i.imgur.com/0gVOaC5.jpg (linked due to image limit)
Clamped the end of the wire in a vise.
http://i.imgur.com/hjrjMxO.jpg (linked due to image limit)
Had people stand on the bar (we would up with two guys, 200lbs and 180lbs each)
http://i.imgur.com/k75U4P1.jpg (linked due to image limit)
The ring on the terminal failed, not the crimp! We did math and determined that the connector failed at about 290lbf, close enough to mil-spec IMO.
We then sectioned the crimp, and sanded it, to reveal a SOLID chunk of copper resulting from the crimp. This is why you do not need to solder proper crimps, ever, because there is literally no volume for the solder to occupy. Everything is in good contact, if not welded together.
Then, out of curiosity, we sectioned an AndyMark brand 6awg crimp. The results were less than ideal… you can clearly see un-crimped wires and/or air-gaps between the wire strands.
Even more curiosity ensued and we tried crimping with a vise, with terrible results. No welding, tons of air gaps, a generally terrible crimp. Don’t do this. The picture is both sides of the sectioning cut.
Hope this was a little enlightening, and I hope you go test your various wire crimpers.