All of the bullets I have for my AR-15 are 55 gr. Whether fmj, hp or psp, they all shoot to the nearly the same place on target (using the same recipe) without sighting in the gun again for each bullet type. I have a chance to do a trade for some 68 gr hollow point hornady bullets for reloading. Does anyone know from experience how much that would affect my aim point (resetting the scope) out to about, say, 300 yards? Thanks. :thumbup:
The heavier bullet will likely drop a bit more but that's about it. The wind will have less effect on it.
Using a 200 yard zero and 2.6" sight height will give you somewhere around...... 55 grain 100 yards +.8" 200 yards zero 300 yards -6.2 68 grain 100 yards +1.2" 200 yards sero 300 yards -7.5 The heavier bullets are more stable in the wind and carry more energy down range.
Thats just copied from a ballistics table. Your results will vary but that will give you a ballpark idea. I believe the data is for a 24" barrel. I have yet to find a ballistics calculator that is spot on. You have to shoot it and see to be exact. How long is your barrel? I have a bunch of chronograph numbers for a 16" barrel.
I'll post some of my chronograph numbers for factory ammo. This is out of a 16" 1-8 twist with the chrony about 10ft from the muzzle. All figures are an average of at least 5 shots, rounded to the nearest 10fps. Federal American Eagle XM193 55gr fmj 3190fps Remington UMC 55gr fmj 2920fps PMC 55g fmj 2830fps Ultramax 68gr otm 2580fps Black Hills blue box 69gr smk 2780fps Federal Match 69gr smk 2740fps Ultramax 75gr otm 2500fps Black Hills red box 75gr otm 2600fps Black Hills blue box 75gr otm 2660fps Federal Match 77gr smk 2570fps Black Hills red box 77gr smk 2510fps Black Hills blue box 77gr smk 2580fps :thumbup: