I found that is sometimes necessary with the hex dies and thinner walled lugs, think it was a no-name one from CEF. The indent-style seem more forgiving in that respect.Nice, I just tend to use the next size die down from the one I need ie 10mm cable and 10mm lug I'd use a 6mm die and they're on there solidly!
The SWA-branded 'TQ' lugs are nice, thick walled and slightly flared so cable enters easily and the lug tends to keep the crimper in place until you get at least one crimp done.
Prysmian ones (I think I got from Edmundson) seem to fit the same SWA-brand die but lack the flared entry.