There are lots of old guns, Darnes included, that have cracks in the stock. If the stock is loose on your Darne, email me, and I help you get it tight. I think that is critical to keeping them from cracking.
But, a 70s vintage Darne isn't that old. If it were me, I'd use whatever I had on hand. Do you expect to load and shoot more than 5-10 rounds a day? That is a pretty good day of hunting, in my part of the world. I suspect your 20, could handle that level of use, with those loads.
I have never been sold on the benefits of obturator discs on the higher grade Darnes, outside of the fact they are a pretty neat piece of machine work. I've seen all manor of things claimed for them, reduced recoil, reduced shell setback, longer life, world piece, yada, yada, yada. My sub 6 lb. Darnes let me know when they have gone off. It is hard to escape physics, for the most part, and I am OK with that.
Do enjoy your trip. I came into the oddest thing some time ago, a free couple boxes of Remington Express 20 gauge 2 3/4" magnums, in, of all things, 7 1/2 shot.
I intend to use them in my Darne, or my Richland 3" 20.
They were free. Good enough reason for me.
Best,
Ted
