45-70 Ballistics help

y2k

y2k

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45-70 load in an 1886 Winchester. 405gr Lyman cast lead (wheel weight)
39grs of IMR 3031 and a half inch of wad. I have no idea of velocity. Shoots 6 inches high at 100 yds. My questions are.

1 what would muzzle velocity be in 26 inch barrel?
2 what is a 6 inch high at 100 yds zero? ie 200yds zero?
 
1375 fps estimated, basically the same vel. as Rem. 405gr. factory loads, I'm not sure of the drop tables but you do not want to have a 100yd. sight in that is 6" high. I would suggest that if you want something better out at 200yds, you need to flatten that trajectory and to do that you need to up the velocity by about 500 fps.
When sighted dead on at 100 yds. your load will be 22inches low at 200yds.....if you up the vel. to 1800fps it will drop 12 inches at 200yds. which I think is doable.
 
Problem is that I`m at the bottom of sight elevation now. and it is a 1896 manufactured 1886, don`t really want to go any faster. sounds like i`m maybe a 150 yd zero?
 
y2k said:
Problem is that I`m at the bottom of sight elevation now. and it is a 1896 manufactured 1886, don`t really want to go any faster. sounds like i`m maybe a 150 yd zero?
Click to expand...
You need to install a taller front sight. Adjusting point of impact by adjusting loads is folly. Find a bullet-load combination that groups well and adjust the sights.
 
y2k said:
Problem is that I`m at the bottom of sight elevation now. and it is a 1896 manufactured 1886, don`t really want to go any faster. sounds like i`m maybe a 150 yd zero?
Click to expand...

If you raise the load too high you risk swelling the chamber in that old rifle, I doubt the .45-70 has a nickle steel barrel from 1896. My .40-65 from 1894 doesn't.
 
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