Feeding Your Rifle -- Some Basics on Bullets:

This is a difficult subject to encompass in such a short space as things which people expect from bullets are very much dependent on what purpose a shooter wants to use his rifle for.  A firearm is a tool made by man and wielded by man.  As one selects the correct nail for a construction job -- so we as riflemen select the bullet for the purpose we intend.  For this little article lets look at bullets or what we will feed our rifle to get the maximum performance out of it for our needs.  We will be looking at bullets and some ballistics here but my intent for this is not scientific but rather something which any of us can use without the need for calculus and physics lessons.

Bullets are pretty much divided into two categories -- Hunting and Target.  Ballistics is divided into three categories -- Internal, Exterior, and Terminal.  Internal ballistics concerns the mechanics of the powder and bullet during combustion and in the process of traveling to the end of the barrel.  Exterior concerns the efficiency which the bullet passes through air, and Terminal concerns the physics of what happens to the bullet when it is traveling through its target.

Target Shooters -- Little Dilemma: 

Target shooters have little concern over terminal effects as the only thing which the bullet needs to penetrate is a piece of paper.  The same shooters are aware of internal ballistics which is why they hand load.  Target shooters are totally unforgiving about exterior ballistics.  In a nut shell, the more efficiently the bullet passes through the air, the faster it will reach its target and thus the less the wind will effect it.   Also, inclusive in the efficiency of the bullet in terms of penetrating the air is a relation with the ability of said bullet to remain within its axis of flight without yaw or pitch.  Yaw, pitch, precession and mutation cause mammoth drag on a bullet so degrade flight efficiency and create an unacceptable level of dispersion of a shot group.  

Most match bullets are carefully balanced and designed strictly for exterior ballistic efficiency.  The problem for the manufacturers of such bullets is as much one of exact design as well as consistency in manufacturing.  National Champions will go from first place to tenth place if a bullet does not perform like the others and scores an eight instead of a ten for a shot.  Yes, the Army and police use the Sierra Match King bullets for sniping despite the fact that these bullets are made from the base up and thus have a open tip.  The logic behind this is not one of terminal ballistics as much as the exterior performance which allows a sniper to achieve a far greater hit probability in a kill zone.   They accept the fact that the bullet will probably lose its jacket and fragment but under the situations they face it is of little importance as the bullet will kill just as dead as a full metal jacket bullet will.

Hunting Bullets -- A Compromise

Hunters have a much higher demand on the terminal performance of their bullets than a military sniper, as a hunter must have a bullet which can remain intact when penetrating thick hide and then function properly once the hide has been penetrated.  This is real tricky business as for a bullet to expand terminally there are two requirements.  First that the bullet is traveling fast enough so that when it strikes an animal -- it does what it was designed to do which in most cases is to expand in a controlled fashion.  Second, that the bullet be constructed so that it retains its weight, maximizing its kinetic energy in the animal.  There is far more compromise in terms of exterior ballistics in return for the bullet to perform as it was intended when it strikes an animal.  The compromise is logical as the majority of hunting shots are well within 300 yards and are against kill zones which are about twelve inches or greater in diameter.  A standard NRA Short Range 300 yard target has a 10 ring of six inches in diameter with an X ring of about two inches diameter.

I will not preach one type of hunting bullet over the other.  All have their specific game behind their development.  The major manufacturers also provide pretty good outlines of their game bullets verses the game they are intended to be used for on their Web sites.  In addition, many hunters have stuck with one brand and type of bullet for their lives and if these work for them they should stay with them.  So, commenting on one type of expanding bullet over the other does not warrant much discussion. 

 Here are some comments concerning center fire rifle cartridges, fired from your Model 70 or 700 and not the lever gun. 

            a.  All modern centerfire cartridges follow very close to the same path through the air to about 300 yards.  At five hundred yards and beyond there are significant differences in elevation required between many cartridges, even those that have the same weight bullet but are of a different design.

             b.  Flat base bullets are just fine to about 300 yards but their exterior performance past 300 degrades significantly verses a boat tail type bullet.

            c.  The condition of the base of a bullet is more important to its flight characteristics than deformation of the tip.

             d.  Rate of twist of the rifling will matter only if you are using a bullet which is far too long for the twist to stabilize.  For 30 caliber bullets, a 1 turn in 10 twist will take bullets up to about 200 grains and stabilize them.  A 1 turn in 12 twist will perform well with bullets up to about 170 grains and may get to 180 grains in weight.  It is better to over spin a bullet than under spin one. 

             e.  There is no such thing as a flat shooter.  All bullets drop to the ground the instant they leave the barrel at the same rate of fall as any other object.  Zeroing at 100 does not mean your bullet will strike center at 200, no matter its muzzle velocity.

             f.  Wind ‘bucking’ ability is due to the speed which the bullet gets to its target.  Bullets which reach their target faster allow the wind less time to effect them. 

             g.  The faster the velocity, the faster the bullet slows down. 

What To Do?

 If I were to go on a hunt against game that I was not familiar with here is what I would do.

             1.  Research the game animal and determine the size of its kill zone (s) and the normal ranges which shots are taken on the type of game.  This will give you a very clear idea about how well your equipment must perform in order for you to be a success.

             2.  Research the web pages of the major ammunition manufacturers and select the types of bullets which they recommend for the game you are hunting.  There will be several types no doubt.  If your planned shots are past 300 yards, I would then select those bullets that have a boat tail and have a sharp tip (Spitzer Tip) as exterior performance will become as important as terminal performance when you have crossed this border of about 300 yards.

             3.  I would then reduce my choices of bullets to match the twist rate of my rifle.

             4.  I would purchase a box of each type of bullet I had selected and evaluate their performance on a firing range.

Next article for the Goosepit will be an evaluation of your selected bullets at the range so that you can take confidence in your selection of bullets for your purpose.

 Be safe and enjoy the beautiful weather we have been having in the North West! 

 Gene Econ