NBHunter, as usual, this topic slipped off into a non answer. The simple answer and most dierctly provable is that the NEF 45-70 is a Marlin load clas rifle. The obvious evidence for this is that NEF did in fact chamber the Handi Rifle in 450 Marlin. It is very likely that the NEF will stand up well to Ruger class loads, but the throat must be reamed longer to accept the longer OAL of the Ruger loads. In past Ruger chambered their #1 (and #3 too???) with a long throat which allowed a longer OAL which allowed for a bit more powder to be stuffed into case, and such loads won't chamber in the shorter throat of the NEF.

There are Marlin class loads which will easily allow you to push 405 grain bullets to 1800 fps. Such a load with a good bullet will shoot completely through any animal you are likely to aim an NEF at. I shoot 405 grainers out of mine at 1600 fps and it is all I care to shoot off a bench.

An update to my question. I had not mentioned that the H&R was a "Shikari" model. I didn't think it would matter until when reading in the Hornady #3 under the level 1 loads, low and behold there listed along with "trapdoor" and "rolling block" was "H&R Shikari", Huh? Is the Shikari model built weaker or are they just covering themselves?

If I am limited to lower preasures, I'm not too bummed because the more I read the more loads I am finding for 400-500gr bullets at good velocity yet still staying to low preasures. I don't think I'll need more than that, if so I'll just use my 416 Taylor.

i don't think the Shikari model has been produced for 20 or more years. I believe different steel is used in the more current models that accept 30-06, 270 etc. My handi rifle was originally a 30-30 +20 ga model. I later got a New England 45-70 but used the older frame as I like the colour case hardened look better than the blued steel of the newer gun. I only shot black powder loads in the gun but got excellent accuracy with 65 gr of black and 385 cast bullets. It would keep 5 in 1 1/8 inch and i am not a good caster and shot anything with a good base if the nose was wringled or not. Velocity in the 20 in barrel was a whopping 1150 feet per second but was very consistant + or - 15 fps for 5 rounds