Does anyone here use the Greenhill formula in choosing their muzzleloading boolits?
Does anyone here use the Greenhill formula in choosing their muzzleloading boolits?
I have used this Greenhill Thorium to get an idea of where to begin, it just gives a general area/idea of bullet length and weight to start, with a given twist rate.
Keep in mind the Greenhill formula was derived for a muzzle vel of ~2800fps. It usually works ok if you are well above speed of sound. FWIW, the bullet shape used was a 'football' contour.
I believe the Greenhill formula was developed for cannon and artillery projectiles. I've had better real life fit with my bullets and twist choices changing the constant. At our slower velocities, at C of 135 rather than 150 insures more stability. M. Rix
Chill Wills
The full set of equations were used for artillery. The shortened versions by Greenhill and Miller were done for us 'common' folks using small arms
BP | Bronze Point | IMR | Improved Military Rifle | PTD | Pointed |
BR | Bench Rest | M | Magnum | RN | Round Nose |
BT | Boat Tail | PL | Power-Lokt | SP | Soft Point |
C | Compressed Charge | PR | Primer | SPCL | Soft Point "Core-Lokt" |
HP | Hollow Point | PSPCL | Pointed Soft Point "Core Lokt" | C.O.L. | Cartridge Overall Length |
PSP | Pointed Soft Point | Spz | Spitzer Point | SBT | Spitzer Boat Tail |
LRN | Lead Round Nose | LWC | Lead Wad Cutter | LSWC | Lead Semi Wad Cutter |
GC | Gas Check |