After a couple successful 16 gauge Speed Load conversions, I figured I'd like to find a 2-piece carrier for my 1939 12 gauge. The usual parts suppliers didn't have a full 2 piece carrier assembly available. However, Numrich had a back piece and MGW had a NOS front piece along with a new locking block latch and spring. I figured I'd see just how interchangeable these parts are. It actually saved me a good bit of money to get the carrier pieces separately. When everything arrived, I gave the parts a quick inspection to ensure the 2-piece carrier fit together correctly. Once confirmed, I proceeded to break down the shotgun. The first thing I noticed was that the new locking block latch would not fit into the recess so I took a measurement and carefully filed the new latch to match the original. Once fitted, everything went together as it was supposed to, and the new 2-piece carrier assembly lined up perfectly. The next step was the function test. I locked the bolt back, slid a shell up through the new carrier into the magazine and it was instantly whisked into the chamber just as intended. I attempted several more times with the same result. I will run some rounds through it sometime in the next few days and report back. Things are looking good, though.
I have never understood why Speed Load requires a new locking block latch. Especially on pre-1958 guns that still used the old thin rail bolt and locking block. I’m wondering if you filed your new latch to match the dimensions of the old one.
The biggest difference I see between the 1 and 2 piece carrier locking block latches is where they position the shell coming out of the magazine. I believe the two piece latch positions the shell further into the magazine for carrier clearance. It could very well work perfectly fine with the original latch. I've never actually tried it. Yes. I filed a few thousandths from each side of the new latch where it is pinned into the locking block recess. It now matches the width of the original latch.
That makes sense. Now that you mention it I do recall that the two-piece carrier is a little bit longer than the old style. I still wonder if the early Speed Load carriers, used from 1953-58 were just as long.
