RE: Max Point Blank Range
I will give you an example.
I have an inline muzzle loader that shoots Precision Rifle sabot bullets. They weigh 350 grns and have a BC of .376. My gun pushes them at around 1600 fps muzzle velocity.
I want to hunt at ranges out to 150 yards on deer sized game. A deers vitals are pretty large, so if you can place a bullet in a 8 inch circle you will probably kill it. To be sure we will go with 6 inches, this is what PBR on deer sized game is figured at I believe.
Now I want to know what range to sight my gun in at to achieve this so I don't have to guess on hold over at long shots and hold under at closer ones. What that means is my bullet can't rise more than 3 inches or drop more than 3 inches on the way to the target at the distances I want to hunt at.
For my gun the Max Point Blank Range is 160 yards if I zero my scope at 136 yards. So to make it easier I just sight in for 130 yards. This was with a 1 inch sight height. Which basically means the center of my scope is one inch above the center of my bore.
This puts my trajectory like this.
2.8 inches high at 75 yards and 2.6 inches low at 150 yards. At 175 yards I am 6.3 inches low and at 200 yards I am 11.5 inches low.
If I change the sight height to 2 inches it will effect my trajectory at the above distance by about .5 inches, less in most cases. It actually makes it seem as if your gun shoots flatter at longer distances, but makes it shoot higher up close.
What all this does is lets me put my cross hairs right in the center of a deers vitals out to 150 yards and pull the trigger. I don't have to guess how much to hold over or exactly what the range is, as long as I know it is within range. Will the bullet hit exactly where I aimed at 50 yards and 150 yards? No, but it will still strike the vitals and kill the deer cleanly.
Keep in mind this is assuming your gun can shoot good groups at these distances. If your gun is only capable (or you) of 4 or 5 inch groups at farther distances you best take this into account. If you know your bullet is going to strike the target 3 inches low at 150 yards and it is only capable of 4 inch groups then there is a good possibility it could actually strike 7 or 8 inches low instead.
Did that help, or just confuse you more?
Paul