Hence, w' may be 128 grs. or 172 grs. as the velocity is greater or less.

To determine D,, difference in powder charge, using same quality of nitrocellulose powder and the same projectile.

Problem 13G.

To determine D, for difference, D,, in powder charge for same projectile.

To determine the difference, D,, in velocity, for difference, D, in length of barrel.

in which B is the length of the barrel for which the velocity is known.

V'V+or-Dy.

if the barrel is shorter,

+, if the barrel is longer.

Illustration. If the bullet travel of the Springfield is 22 inches, and the muzzle velocity is 2700 f.s., what will be the velocity, if the barrel be 20 inches, or 24 inches.

Increasing the weight of the bullet, using the same charge and quality of powder, INCREASES the chamber pressure. For illustration, using the 172 gr. bullet instead of the 150 gr. with the same powder

charge, increases the chamber pressure about 4000 rounds.

Increasing the powder charge, without increasing the volume of chamber, using the same bullet, INCREASES the chamber pressure.

Increasing both powder charge and the weight of bullet, INCREASES ENORMOUSLY the chamber pressure.

Using the same charge and quality of powder but of finer granulation increases the chamber pressure. For the interrelationship of weight of bullet, length of barrel, powder charge, density of loading, volume of chamber, granulation of powder, pressure, etc., consult Vol II.

In the meantime, DON'T deviate from the instructions given with each brand of powder, and weigh the same.

8

T

lows:

CHAPTER VIII.

To Determine the Range.

HE horizontal range of a projectile having a given remaining velocity is determined as fol

To determine the horizontal range, X, in feet.

X=CS(v)-S(V) {

S(v) S(1668)=6500.8 Table 1.

S(V) S(2700)=2644.8

For. 24

3856.0

.389

1500 ft. 500 yards.

Correction in range for small variation, say not exceeding 100 f.s. in muzzle velocity.

DX=+or-1% of X, for 20 ft. variation in V. For. 24a. in which DX is the difference in range.

+, when V is greater than normal.

when V is less than normal.

Illustration, Variation in muzzle velocity is, say 60 f.s. what is the correction in range for 500 yards? DX=1% of 500-5 yards for 20 f.s. variation. Hence DX=15 yards for 60 f.s. variation, and X' =500+15=515 or 500-15=485 yards. That is, if