OK, actually my birthday was back in April, and I bought my birthday present to me in March...and due to the current incredibly slow NFA paperwork processing times, it just got here today. Oh, joy!
The problem with the Reising was that it has many moving parts, a large percentage of which were hand-fitted at the factory. This is fine for guns not subjected to hard use and the Marines' "group cleaning" method wherein all guns are disassembled and dumped into pots of hot water, then everyone reassembles their guns with whichever parts they grab back. You can do that with some guns, but the Reising was and is not one of them.
Cock the gun via this charging handle under the stock, just behind the forward sling swivel. This one it a bitch to cock if the hammer is down.
Weather permitting, it's going out to the range tomorrow morning once a certain guest arrives. Stay tuned for an AAR. Here's hoping that it works!