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Interesting post! I grabbed an old Hornady manual that I had close, and using the ballistics chart for their 60 gr. HP, I find the numbers your ballistics prgram generated are very close. And you are correct, Dennis. Your velocity would have to be MUCH higher for for the drop to only be 2.5" @ 300 yds. Even a couple hundred fps either way won't have that kind of effect at 300 yds.
One other poster had a good point: Make sure you never rest your barrel on the bags while your shooting. I learned many years ago that this does really weird things to trajectory. I suspect your 300 yds. isn't really 300 yds.
I don't own a rangefinder, but I borrowed one once, and found that they can EASILY be inaccurate. Any little minute movement of the rangefinder in your hand could easily have it pointed at something at a different distance. The one I borrowed was one of those expensive Lieca's. I borrowed it to use to set up my shooting range here at the house. The button you pushed to find the range took quite a lot of pressure to activate. I found it was impossible to get accurate, repeated readings without resting the rangefinder on something very solid. Don't believe me? Take a 4x scope, hold it in your hands and try to steady the crosshairs on something 300 or so yds. away. Then imagine trying to steady it while pushing a button!
Regarding chronographs, I have over the last 20 or so years owned 4 different brands of chronograph. I current own a Chrony Beta Master. The Chrony, though it's the easiest to set up, has hands-down been the worst and most unreliable chronograph I've ever owned. It is very sensitive to light conditions. This is SO frustrating when working up loads. Also, the user interface is very frustrating and confusing. I recently obtained a CED Mellinium II. Since I have my own range, I'll likely leave it set up and just cover it with a tarp, so ease of set up won't be an issue.
Several years ago, I was at a public range shooting my 220 Swift. This is an incredibly accurate rifle that from time to time groups my favorite hunting load into the 1/4"-3/8" range at 100 yds. I stapled one of those gridded targets at what I was told was the 300 yd. backstop. I was firing a handload that pushed a 55 gr. Sierra SBT in the 3800 fps range according to my chrono. I proceeded to fire a 3 shot group which measure exactly 1.1". (No, I don't think I could ever do that again!!)I was quite happy with my group so I kept the target. Some time later as I was admiring the target, I notice that the group was about 6.5" below my point of aim. A red flag popped up in my head as I'd studied the ballistics of the cartridge long enough to know that bullet drop shouldn't have been nearly that much. I ran the numbers through an old DOS based ballistics program I had and discovered that was the amount of drop for 350 yds. Some time later back at the range I began questioning other members as to the distance to the far backstop and found it was actually 350 yds. Subsequent firing of other rifles at that backstop and comparing their bullets drops to ballsitics table proved this to be true. My point here is that you should probably trust your program and question your rangefinder!
Regards,
35W
