Montana Hunting and Fishing Journal

Clarke's Marksmanship and Shooting Tips

by John R. Clarke, Shooting & Firearms Editor ©

As a general rule, "rifle accuracy" is primarily determined by the "screw holding the butt plate."

As a general rule, wind has more effect upon slower moving projectiles than faster ones.

As a general rule, "winds from the right" effect a projectile less than "winds from the left." In rifles or pistols with left hand twist rifling (quite rare) the opposite would be true.

As a general rule, "winds from the left" decay the path of a projectile (make it hit lower on the target) and "winds from the right" increase the path of a projectile (make it hit higher on the target). In rifles or pistols with left hand twist rifling the opposite would be true.

As a general rule, think of the hands of a clock in the 10AM to 4PM diagonal when trying to determine how cross winds effect the flight of a projectile. Winds from the right cause the projectile to drift towards the 10AM direction and winds from the left cause the projectile to drift towards the 4PM direction. You will notice each of these directions are "higher or lower" than the actual representation of the cross wind directions - 3PM to 9AM or 9AM to 3PM.

As a general rule, "hot loads from hot barrels on hot days" are more accurate than "cold loads from cold barrels on cold days."

As a general rule, "over stabilized projectiles" are more accurate than "marginally stabilized projectiles." This is primarily why the .30-'06 SPRG with its 1:10 twist has always been more accurate with equal weight projectiles than many of its 1:12 or slower twist cousins. The same analogy holds true for 1:7 twist M16A2 rifles over their 1:12 twist M16 predecessors.

As a general rule, a muzzle velocity of 2,800 FPS is the desired muzzle velocity for most big game hunting. At velocities greater than 2,800 FPS, projectiles often will not hold together upon striking big game. At lower muzzle velocities, projectiles may not provide sufficient velocity at longer ranges for dependable bullet expansion and energy transfer.

As a general rule, flat base spitzer projectiles perform better in big game hunting situations than boat-tail projectiles. This is because the boat-tail projectiles tend to tumble after striking, which can cause them to experience an exorbitant number of jacket-core separations in these situations.

As a general rule, the difference in trajectories between flat-base spitzer projectiles and boat-tail projectiles is less than one minute-of-angle.

As a general rule, faster moving projectiles hit lower on the target at shorter ranges than do slower moving projectiles. The opposite is true as range increases.

As a general rule, shot dispersion on the target is not "up and down" or "left and right" but at some diagonal (10AM to 4PM or 2PM to 8PM) to these directions.

As a general rule, the most accurate type of projectile is a "wad cuter" followed by (in descending order or their accuracy) - "round nose projectiles, spitzers and boat-tail projectiles.

As a general rule, projectiles do "go to sleep" (become stabilized) at some distance downrange but they begin to "wake up" (become unstable) as range increases.

As a general rule, projectiles do not have just one "ballistic coefficient" which is good at every velocity level, range or cartridge - they usually have a different one for each of these.

As a general rule, ballistics coefficients, as published by bullet manufacturers, often have little relationship to reality. In many instances, these figures are as much as 10 to 30% greater than the actual ballistic coefficients of projectiles in flight.

As a general rule, ambient temperature effects the flight of a projectile greater than any of the other environmental conditions. This is followed closely by altitude and more distantly by relative humidity and barometric pressure.

As a general rule, projectiles actually have flatter trajectories in wet, rainy or humid days than they do on dry, less humid days. This is because humidity acts like a "bullet grease," decreasing the drag of the air upon the projectile.

As a general rule, projectiles give flatter trajectories on warm, humid summer days than they do on cold, dry winter days. This is because these conditions increase the effective ballistic coefficient of the projectile(s).

As a general rule, muzzle velocity of projectiles is reduced approximately 1 to 1½ FPS for every degree below 70 degrees F. The opposite occurs for temperatures above 70 degrees.

As a general rule, targets viewed over flat ground appear larger and closer than targets at the same range over broken ground.

As a general rule, big game targets below the shooter appear larger (and closer) than equal distant targets above them.

As a general rule, always hold slightly below your desired point of aim for targets, either uphill or downhill from your position, because a projectiles trajectory is based upon "flat range distances" not "slant range distances."

As a general rule, rifles shot off sand bags are loosely supported and tend to hit higher on the target than rifles shot from tighter, more supported positions (e.g. prone with sling).

As a general rule, when zeroing a rifle for big game hunting - zero your rifle 2 to 2½ inches high at 100 yards. This should put you dead on with most cartridges at ranges up to 250 yards or more.

Not discounting the use of quality ammunition and equipment, the keys to marksmanship are three fold - "practice, practice and practice."