Brit & Peter ( and all the other guys across the pond),
Attached is a pic of the L4A3 de-mills that have now become available in the US. These are the only L4 kits available. Also a pic of the previously available Mk I & II MGS demills.
You can see the barrel socket area is gone in the L4A3. Alterego welded in the barrel socket from the MGS demill into the L4A3. The problem is that the L4A3 kits do not have a barrel since barrels cannot be imported into the US.
Once Alterego got the weld up done he had a L4A3 body but since I think he used a Mk I barrel socket the exterior contours would not match the L4A3 in the barrel socket area. Everything internally should be the same as the L4A3.
Modified the bolt stops?? Maybe Peter can answer. I know C310pilot knows since he stated with a Mk II and completely made it into a L4A3.
Joe