I chron mine and with t7 I can get 1700 with light bullets (375 gr) in 54cal. I believe that when the bullet hits subsonic that is where you get wide variations in accuracy especially with slow spins on ml bullets and why many folks have supper accurate guns at 50 and can't hit a barn door at 100. Ogive is the curved bullet shape at the front of the bullet an was on old French word adopted into old English and is used in mathematical discussions to mean/describe diagonal curve. I am fluent in Spanish...I believe that the designer of your calculator simply used the term to show that a pointed bullet shape was the default in his calculations. An example of a non-ogive bullet is a wadcutter. Typically the "pointier" the bullet (the longer the ogive...called a secant ogive) the more accurate the bullet in supersonic/transonic flight as there is less pressure impact to the bullet. Part of the same reason you see very pointy noses on supersonic jets and many rockets.
Spin is a factor too...you typically see faster twist rates on heavier bullets in the same caliber because of the longer bullet. For example, a 200 gr bullet calls for a 1:10 where a 125 gr calls for a 1:12 in 30 cal. and why the faster spin rates
typically shoot conical bullets more accurately.
Of course, the above isn't the only consideration for bullet selection on hunting, rather one of the inputs as is expansive characteristics and penetration, but for our discussion I am sticking to bullet shape and MV
I think you will find this little blurb on ogives interesting....especially the part where he talks about the "windshield" on the 16" battleship round to make it aerodynamically friendly.
https://www.mathscinotes.com/2011/01/ogives-and-battleships/
This blurb talks about bullet shapes
https://www.mathscinotes.com/2011/01/ballistics-ogives-and-bullet-shapes-part-1/
My experience in ballistics comes from being a long time long range shooter with modern firearms and as silencer subsonic shooter. Bullet instability at the transonic velocity is a very noticeable and quantifiable phenomenon. One of the reasons sniper rifles went with secant ogive, higher velocity rounds, heavier weight for caliber bullets is for energy retention and to lessen the impact of air pressure is to push out the entry to transonic, thereby extending effective range.
There is NOTHING secant about the conicals we use, for sure ...hahahah
Now all of the above is a real pretty speech not to mean anything if you don't go out and shoot your particular gun with your bullet and powder load and ACTUALLY see what it does.
I have found that, at least in my guns, that the entry into transonic/subsonic reliably predicts a commensurate drop in accuracy, enough so that I will use that at my max range in shooting my slower moving bullets...for example, in my 58 cal Buffalo Hunter. The blunt, fat bullet and slow spin with slow MV...starting at 1250 fps.... starts to become erratic at 90 to 100 yards.
Last of all, a link to a discussion of transonic entry and impacts to accuracy:
https://thearmsguide.com/5348/long-range-shooting-external-ballistics-transonic-region/
@Speedgoat44 Look at the hornet's nest you kicked!
@longcruise Thanks for the great input and learned discussion. ¡Salud!
