Another observation on stock LOP. All of my Darnes LOP's are at least 1/2" to 1" longer than what I would normally shoot in either straight grip or semi-pistol. My standard actioned guns I shoot 14 5/8" LOP on a straight stock. My Darnes with straight stock are 15 1/4". Stock dimensions at either the dac, dah, toe in/out and cast remain the same. Hand placement is different when using a Darne, the feel will be much different than what you're used to but it takes no time at all to get used to it.
When it comes to the old school tight bores and chokes, I found that using loads with felt or fiber wads improves patterns a lot.
I've owned a few Darnes over the years. Still own and use a nice Halifax 16 as my go to chukar gun. Old ones, new ones, V and R's, all lightweights, 12, 20, 16's. I seriously loved them all. There's a few I still wish I had. If I ever buy another one, I'll be bringing it in from France. The prices there are much more reasonable for higher graded guns. In the future, I'd like to find a nice Bruchet 12 or 16, straight grip, V-19 or V-21 with 28" bbls.