It's old red gore and new scarlet from GW 50/50. Over a Halfords red spray primer (it's really nice as a base for flesh and reds/browns and super matt).
Weathering is still tricky, getting to the smaller areas is always a pain. I'd love the do the ultra clean stuff that you do sometimes but I always enjoy making things look used and grotty. When these are in metal I'll have another go.