I don't have a Henry and have never used that ammo, and likely never will.
What I can tell you is that accuracy is a combination of the gun you have, the ammo you have, and the person doing the shooting. ONLY testing all these together will tell you what you get. Anyone else, shooting a different gun, might easily have different results.
And, there absolutely ARE rifles, (lever guns in particular) that will not feed correctly with rounds over the industry standard maximum length. Pistol caliber lever guns, and Marlins in particular are notorious for that though they certainly aren't the only ones which will do it.
Personally, I'm not a fan of the uber heavy bullets. While they do deliver some increased performance, I've never found that anything I needed, and not enough to justify the increased recoil, increased cost, and possible fit and accuracy issues that go with shooting a bullet significantly heavier (and so, LONGER) then the standard weight range.
Also, a word about "+P". There is no standard for +P in .45 Colt. Therefore, ANYTHING from 1psi (one psi) over standard max pressure all the way up to "blow your gun up like a grenade" is technically all "+P" pressure.
You need to know about WHAT The maker is loading to, (If they'll tell you) and if it is suitable in your gun.
Note that I said "suitable" not "safe". Suitable is always safe, but safe is not always suitable. Again, this is something that only testing with your gun and ammo will tell you for certain.
Good luck with your hunts, but DO some testing with the ammo you're going to use before going afield.
And, if you /your brother are going to shoot whitetail deer with the pictured "bear loads" expect complete penetration as the norm.
