sectional density?

[bigbore50ak]

ok heres were im comfused. ive been reading about sectional density and i under stand what it is.ive read that a sd of .215 and a average of .237 is good for med game. and that .270 and a ave of .279 is good for larger game. e arthur brown is trying to sell there brm line with a .270-.290 sd @ 2500fps is best for hunting because of the time the bullet stays in the animal. so what i dont understand is does velocity counterdict what sd you yous for a givin game or what. please straightin me out. jason

[AMMOe]

Sectional Density is derived (I believe) taking the pound weight of a bullet and dividing it by the square of the diameter in inches. It is a number representing the diameter to weight ratio of a bullet. I think that there are too many variables to just say a .295 (or what ever) is best for deer or some other game. I don't know if buying bullets based solely on their section density is a good thing to do. I always figure that the longer the bullet for a given caliber, the better it will penetrate. It's physics: the front end of the bullet comes to a screeching halt when it hits something but the back end is still moving, pushing it on through. This is where the velocity comes into play. The harder the push, the more penetration and expansion. This Brown fellow is probably saying that HIS bullets of .270 - .290 SD are best shot at 2500 ft/sec to maximize expansion qualities. The idea that numerical sectional density values can define bullet choices seems to say that bullet construction is meaningless and I think he's adressing that in his statement. His SD/velocity recommendations reflect his knowledge of the construction and performance history of his bullets. If you are sold on his bullets you ought to take his advice. ~Andy

[BigBob3006]

Big Bore50AK,
Sectional density is somewhat misleading. All the bullets of a given calibre and weight will all have the same sectional density regardless of the construction or design. If all other variables are constant, the bullet with the larger S.D. tends to penetrate deeper than one with a lower S.D. "IF" both bullets hit in exactly the same location from the same angle. IMHO, consider S.D. only as an indicater, not a rule. Good luck.