Prototype 7.62x51mm Sterling rifle

[Beerhunter]

That looks like a 30rd FAL mag to me, BP.

I think that someone has correctly ID'd the mag as from an L4 (7.62 mm Converted Bren). One was not supposed to use L4 magazines in SLRs but my boss did for years without a problem.

Imperial measurements FALs were called the SLR (Self-Loading Rifle) or more properly the Rifle, Self-Loading L1A1. In addition to not using Metric, the SLR did not have a full-auto capability.

The whole thing looks like a bit of a dogs breakfast to me. I have severe reservations about it.