The Russian 7.62 round is older in design that the 7.62 NATO that a private arms seller in England was authorized to sell to Syria.

No proof that the ammunition was actually delivered and the permission to sell was revoked in a reasonable time.

Since the rifles used in Syria are Russian design and use ammunition that is not compatible with the 7.62 NATO rounds authorized, it is really a stretch to blame the Brits for the atrocities committed by Assad.