Luckily for me this was on the same night I was looking for a cyclone missile launcher that I could use for my terminators as they get very limited weapon options it seems. Enter Anvil Industry who I've seen banded about a fair bit for alternate space marine parts. They had just what I needed on both counts.
I've just now sat down to test the multi option special weapons, and I'm really very impressed. The (optional extra) magnets are snug in the indents on the pieces and the resin is very clean and well cast with good detail, I managed to cut, clean and glue one complete 'carbine' in under 5 minutes.
I'm really very pleased and would highly recommend these guys to anyone looking for similar options, or any other space marine type options to enhance their forces, or for a change from the standard GW options :)