The grouse population in the Champlain Valley has been making a bit of a comeback lately. We'll be on 500 acres of family land--hardwoods with numerous 5-30 acre clearcuts and no hunting pressure recently. I was up there last thanksgiving and the locals reported quite a few flushes encountered while harvesting sugar or scouting deer. But you're right Ted, 10 flushes worth firing at per day would be pretty hot grouse shooting!
No looseness at all on the R15. Geoff Gournet went through it in 2016 with a full strip clean and adjustment and pronounced it ready to go.
Drew, thanks for running the numbers. I went through a similar exercise and concluded that the physical forces generated by a 1-ounce load at MV of 1150-1220 from a 5.75 gun are well within the ranges routinely encountered by pheasant hunters, waterfowlers, and pigeon shooters using "standard" 12-gauge loads in guns designed expressly for those sports.
Having said all that, what I have on hand is a couple flats of B&P Competition One shells in 8 and 7.5. That's likely what I'll be using in the Darne. I'll have a 6-pound MF Ideal 16 along as well and plenty of 1-ounce shells for that. Don't worry, Ed, I'm not much of a threat to the grouse population. If we get a few flushes and I can keep Gilley in range, I'll call the trip a stunning success!
Bill