300 gr 45-70 bullets shoot 14" higher than 405 gr 45-70. Is this normal?

[Les in Wyoming]

I am shooting 50 gr 4198 under 300 gr poly-coated, pan-lubed bullets. For my 405 grain, I am shooting 40 gr 4198. The difference in where they hit is incredible. Does 100 grains of lead make that much difference? If that is the case, then it would seem that 300 grain bullets would be a lot flatter shooting. Maybe I am missing something. Does the lighter bullet normally hit that much higher?

I like the 405 grain because that is what the 45-70 was designed to shoot. I can sometimes get good accuracy with it. But if I want to shoot both in any given situation, would I be forced to back the charge down on the 300 gr bullet to bring it down? That would make it a significantly lighter load for hunting. Maybe I could increase the 405 grain charge, but the 40 grains of 4198 seem to be the most accurate. Any input or notes you can share, I would be much obliged. I am fairly new to the 45-70 and am learning as I go. Thanks

 

[Tac-O]

I would think if the barrel isn't a super heavy octagonal, that shift may be reasonable.

The higher or lower for different weights doesn't matter, as that's only determined by the point in oscillation the barrel is at when the bullet leaves it. If you changed the charges, they might hit closer together due to change in oscillation timing.

 

[WildBillG]

My guess here would be the poly or do you mean moly coating on the 300gr bullet. Those coatings can change things a lot. All bullets wether different weight or brand or bullet shape will shoot to a different point of aim.

 

[Les in Wyoming]

I am using both a Marlin 1895 cowboy (octagon) and a regular Marlin 1895 with a round barrel. The longer, octagon barrel is actually lighter than the shorter round barreled rifle. The loads are consistent in regard to heavier bullets hitting lower and lighter bullets hitting higher. The 480 gr bullet hits about 12" lower than the 405. And that is at only 60 yards! I understand how a heavier bullet will drop more - at a distance. But I would *think* that at 60 or 100 yards, the difference would not be so much. Apparently my thinking is not correct. I am just trying to get a handle on this.

In pistol shooting, a slower bullet shoots higher. This is because it comes out of the barrel as the gun rises from recoil. Whereas, a faster bullet exits the barrel earlier in the rise and therefore shoots lower. If the principle were the same, I would think that the 300 grain bullet is faster, and therefore would tend to shoot a bit lower - or at least comparable to the bigger (somewhat slower) bullet. But it is the opposite here. If I were to back down the load of the 300 gr and make it shoot slower, it might hit lower. But then I am losing all advantage of a lighter bullet which can shoot faster at the same pressure. I hope someone can help me make sense of this.

 

[wild_musk]

I know this is an old thread, but I just found it, and wanted to say I experienced the exact same thing with a new manufacture 1886. I liked 405g lead, but wanted something that expanded, so I tried 300g HP and just loaded it moderately high from Lyman data...12-15" higher impact than the 405s. I do not recall velocity, probably 2100-2200fps. Bullets were not coated.

I went to Skinner sights, he has a formula on his page that helped determine the proper front sight height. I have a mill, so I made my own, but was prepared to order one of his. I haven't tried switching back to lead, but I can raise my rear sight if I do. I don't have an answer as to the science of why such a big change, but I'd give Skinner a call, they may.

 

[Fiftydriver]

Likely where your lighter bullets are landing has more to do with vibration patterns in the barrel and where the muzzle is positioned when the bullet leaves the bore. Lever guns are not known for their consistency from load to load, or shot to shot for that matter!! LOL. If they shoot well and you want to use them, just sight in for that bullet and know your rifle is not one that shoots different loads to the same point of impact. No real issue if it shoots to your needs for this rifle.