Dave, I thought those extended magazines were kind of a custom thing. Did they make them off the shelf? I may have my guns confused.
Sorry, I didn't mean to imply that they were off-the-shelf accessories. But there were police equipment agencies that offered extended magazine conversions. I just hoped that one of those might be a drop-in (or snap-in) replacement for the standard box, assuming I could even come across one. I actually think detached larger cap magazines for 8s and 81s will be hard to find and harder yet to fit to standard rifles.
I am at a bit of a disadvantage discussing this because I never even held one of these rifles until today. I will probably know more in a couple of weeks after I get a chance to tear one down and look at the way it goes together.
35Rem, that is a great website. I had found some scattered info in different places, but that site looks like it pulls everything together in one place.