Henry, I have never shot the big bores (45-70s) etc. but I can say that the breezes really blows around the 44-40 bullets. I'm shooting the 1860 and 1866 Uberti rifles at extended range. I am waiting on a good still afternoon to see if the 1860 will take five consecutive 385 M turkeys.
I use BACO's 44-40 powder compression die. The stem measures .415" and I think it along with RCBS's Chargemaster is indispensable.
I wouldn't doubt one bit that magnum primers increase the fouling in front of the chamber. But, Federal LMPM primers sure lowered the SD's in my guns to single digits and that is what I use. The best SD has been a 2.2 and I surmise that on that day, the cases turned out randomly equal. (inside capacity) I load a .432" wax paper wad over the primer inside the case.
The humidity here loves the 16 spot and I use a blow tube between shots. Usually 12 puffs. You can bet good money that the 7th shot will be through a fouled barrel and out of the group. But not always.
I shoot Swiss & OE. and finally settled on OE III because I believe it leaves a softer / more moist fouling in the barrel. Swiss gives lower SDs but OE is more accurate.
I am a firm believer that the hot gas cuts the bases of the bullets...., so I use a wad. John Walters .030 Veg. wads work real good for me but the .060" veg. wads don't. Oddly, .060" poly wads shoot good and the jury is still out on .030" poly wads.
To my surprise, so far the 66 is the more accurate rifle. I have shot a few .050 to .075" 5 shot groups at 50 yards with the 1860 but most of the time 5 will shoot 1.1".
I started out with the Accurate 215 bullet and quickly changed to the 230 E due to the wind. I just received an Accurate 245 with gas check mold that I"m anxious to try out. I use SPG for lube.
These two guns shoot the 230 gr. bullet most accurately in the 1250 fps. range. If one will notice the two targets below, the loading was 36.7 and 36.5 gr. of OE III. I am shooting the same velocity now with 34.2 gr. of OE III. I think Swiss is more consistent between Lots and O.E....not so much. I've noticed variations between cans of OE in the same lot.
1:16, 1:20, 1:30 all shoot good but 1:16 does leave slivers in my bores. Possibly the Uberti chambers aren't aligned very good?
I'm very fortunate in that I can walk to the end of my porch and shoot 1000 yards...so most strings are over a chronograph. My records say that BP is temperature sensitive. I figure ten degrees is worth about 10 fps. and I add or subtract 1/10th of a grain to gain or lose about 10 fps.
But, Loading bullets for tomorrow's weather in N.M. is pretty well a losing proposition.
The two targets below were shot with the 66 last year and I believe I have posted them here before. The picture of the range..... you can't see it in the picture because it is knocked down, but there is a full size coyote silhouette between the rams and the turkeys at the 450 yard line. There is a cow in that pasture and that coyote just enrages her. She will beller, charge and knock it down every time she comes in to water. To the right of the 500 yard gong is a full size antelope silhouette that you can see. He is painted like an antelope and the young antelope bucks can't resist coming up to "him" and give him a good sniffin'.
What else to mention? The sun just went down and the wind is still blowin' so no shooting today. Typical day.
Billy