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Thread: 45/70 Trajectory

  1. #1
    Boolit Master tbierley's Avatar
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    45/70 Trajectory

    I need some help, I install a new rear sight on my H&R BC and I loaded up some Lyman 457132 in 535 grain over 70grn of RS Pyrodex, I need to know the trajectory at 100yds and 300yds.

  2. #2
    Boolit Master 1874Sharps's Avatar
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    I have used this website before to calculate trajectory for my 45-70:

    http://www.mega.nu:8080/traj.html

  3. #3
    Boolit Master Don McDowell's Avatar
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    You'll need to chronograph your load, but typically you'll need somewhere between 15 and 20 minutes elevation adjustment to go from 1-300 yds.
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  4. #4
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    Tom Myers's Avatar
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    Quote Originally Posted by tbierley View Post
    I need some help, I install a new rear sight on my H&R BC and I loaded up some Lyman 457132 in 535 grain over 70grn of RS Pyrodex, I need to know the trajectory at 100yds and 300yds.
    Can't be sure but 70 grains of Pyrodex RS should launch the 535 grain bullet at around 1300 fps.

    My 457132 bullet Ballistic Coefficient tests out at approximatly 0.359

    Given those paramaters, below is the calculated trajectory with a zero at 100 yards.

    Below that is a sight setting table based on a 36 inch sight radius using a vernier sight.

    Hope this helps.




  5. #5
    Boolit Master
    Bullshop's Avatar
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    From Spence Wolfs book on loading for the Trapdoor he says as a rule of thumb figure three minutes of drop per 25 yards out to 300 yards then 4 minutes per 25 yards out to about 600 yards or so.At 1000 yards I used 5 minutes per 25 yards and was very close.
    This is for use with something that will aproximate the service load. The service load firing the 500 gn boolit at between 1270 and 1330 fps from the rifle.

  6. #6
    Boolit Man
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    Based on 32" barrel . . . .


  7. #7
    Boolit Master Gelandangan's Avatar
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    There is a FREE balistic software downloadable at www.huntingnut.com
    You can use it to store your loading data, shooting results, and calculate AND compare trajectories of each of your loads.
    Great software it is.. 100% recommended!

  8. #8
    Boolit Master
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    years ago i bought a h and r buffalo classic, i cryo treated the barrel then i put a 1/2 inch long throat in the back of the barrel. i shoot a 500 grain paper patched bullet over 37 to 40 grains of reloader 7 with a poly wad between powder and base of bullet. man is it accurate and this combination really reaches out their. very very good elk gun. my young son is getting big enough to shoot it with out fear of it and asked me if he can hunt with it so i am going to give it to him. he wants to become a game warden and i can think of no better gun and load to carry in the colorado mountains then that gun. also i shortened the barrel to 26 inches. and put sharps 1400 yard buckhorn on the back. the shorter barrel made no difference in accracy and is much easier to carry than the 32 inch barrel hunting. have fun with yours it is a good gun. johnson1942

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check