IMA-USA use to have dummy guns for sale, and so did Cheaper than Dirt. Or was it The Sportsman's Guide? One of those two. These needed to be cleaned up, and are dang heavy due to the solid receiver, but can be made to make a decent E-11. The ones in the UK are deactivated differently and therefore can not be imported to the US. Bummer too. BATF requires the tube to be chopped into scrap destroying the gun, so a new tube has to be fashioned, but with a different inside diameter. Oh, and you can't use any of the bolt parts, and the barrel has to be welded and plugged. Otherwise they consider it an unregistered machine gun. Deep doo doo.
BTW, the Sterling, according to everything I have read are considered the best of it's type of sub machine gun ever made. Beating out all others, including the Uzi in corrosion test, etc. Pity most of the British Commonwealth nations are phasing them out.