If ya read enuff on the subject of BP "Express" loads you'll find it's related to:
Ballistic coefficient: bullet length determines what's "Express".
Velocity: BP has velocity limits due to low gas/high solids(smoke) production.
Twist rate: shorter bullets need slower twist, longer bullets need faster twist.
Range capability: long range (1000yds) bullets are long, short range (400yds) bullets are short.
These four factors, there may be more, controlled the "Express" rating of a cartridge back in the day.
Express loads were large caliber, .50cal on up. The larger the caliber, the greater the recoil, due to the mass of the bullet...Newton's law :-D
If the ballistic coefficient was to be kept high, for long range shooting, a .50cal bullet had to be long enuff to weigh 600 to 700 grs. Bang that off & it makes ya wanna run away from home! No clam-shell muzzle brakes back then. No rubber recoil pads.
Larger than .50 caliber bullets, to be long enuff, have to weigh even more. The recoil is worse.
So the Express load was developed for BIG game that had to be taken at shorter ranges anyway. Shorter bullets, weighing less, but in large caliber, retaining high cross-sectional density, & higher velocity, still packed a wallop. And their recoil was much less. They just ran outa steam, at long range, 'cuz wind resistance overcame their lighter mass.
Silhouette shooters know all about this subject. Very few of 'em shoot the .50 - 2.5''. It was developed for buffler at short range w/a 450gr lead bullet. And 36'' twist. It's an Express load, by definition, even though it never bore that name.
A 600gr .50 cal bullet needs 18'' twist, 'cuz it's longer. And here comes the recoil!
.40-65 & .45-70 are popular for long range Silhouette, 'cuz the bullets can be long & not weigh enuff to generate punishing recoil.
Kindest Regards,
Doak
