The pressures listed pertain to shooting them in a Marlin sized chamber. The same bullet (flat nose) may produce a 40000 CUP load in Marlin with X amount of H4198, and then loaded to the same length and will inadvertantly produce 10000 CUP pressure MORE in a Ruger #1 because in the difference of the chamber size. I have Hornady's 6th, and am frankly surpised they don't mention the flat nose as being meant for the Marlins more than they do.
Reflex did state thus:
Hey Dr. A. The 350fn load (Marlin only) is XXXXXXXXXXXX in a Remington nickel case (brand new) with a 210m primer. It goes 2025fps out of my LTD-V and shoots 1" groups. I posted before about using this bullet in any other .45-70 other than a Marlin but just in case here goes. Hodgdon called me after several attempts to get a good pressure test kept resulting in high pressures in excess of 50,000cup. I discussed it with them but had already discussed it with Hornady. This bullet as we all know was designed just for the .450 Marlin. The ogive is so far forward on it that in a saami spec chamber the bullet is jammed into the rifling. Marlins throat is unique in that it allows a shallow seating depth. The same load that can't be shot in any other gun safely generates 35,000psi in a Marlin. This is as good an all around Marlin 45-70 load as you will ever find. I have had hunters field testing with this load and a variation loaded in Starline cases with a slightly different powder charge but the same velocity for two hunting seasons. Sand draw jake and his son and son inlaw joined in on the field tests this time. This load handles elk with real authority. It has taken everything from elk to antilope and I haven't had a bad field test report yet. For use in your Ruger the 350rn does a good job with the same powder charge and brass.
My Ruger is the most cooperative gun I have ever seen. I have shot 1/2" groups at 100 yards with it using everything from 300jhp's to 460gr cast bullets. I kiled a doe with it last year with one of the 460grs at 184 yards. A young boy went on the young sportsman hunt with it and a 300gr at 1500fps and killed a doe. The gun just plain shoots whatever you stick in it. reflex264