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View Full Version : Help with finding B.C. and trajectory.



fiatmom
07-22-2011, 02:50 PM
I got the new Lyman cast book and wad dumbfounded when I saw they eliminated the section about ballistic coefficients. The old one had trajectory charts . Does any one have information on the Postell design bullet. What sight adjustments do I have to make from 100 to 200,300,400 yards. I would rather have a close idea rather than wasting bullets.
Thanks:killingpc

Dan Cash
07-22-2011, 06:47 PM
I have the book with the ballistic data in it. It is yours for $15.00 shipped if you want it.

NickSS
07-23-2011, 06:31 AM
If you are shooting a 45-70 (you did not specify) go up about 15 moa for each range increment. This will get you close with black powder velocities.

fiatmom
07-23-2011, 08:57 PM
Nick you are correct about the 45-70. I will try 15moa at 200yds. to see where it gets me. I can't wait to try 300 yards.
Thanks
Nick

montana_charlie
07-24-2011, 01:54 PM
Nick you are correct about the 45-70. I will try 15moa at 200yds. to see where it gets me. I can't wait to try 300 yards.
If 15 moa works for you at 200 yards, then try this progression.

If proven come up for 100 to 200 is 15, then the 'delta' starts at 15.
For 300, come up 15 points plus 1. The new delta is 16.
for 400, come up the amount of the delta (16 points) plus 1. New delta is 17.

Continue until you run out of distance ... or ammunition.

Dan Theodore gave this method to a guy asking for similar help, but the 'delta' for that guy's gun and load started at 11.

I recently modified somebody's Excel file to do those calculation automatically ... if you are interestred.

CM