Second, improved accuracy is not a given achievement. There are a number of variables that determine accuracy improvement - ammunition, gun, and personal technique.
Reloading provides the opportunity to begin matching ammo with the specific gun. Each gun has specific fixed characteristics such as barrel groove twist rate and bore/chamber tolerances. By reloading, you can provide some measure of control over the variable characteristics such as bullet type and weight, shell case length, and powder.
There is no magic formula to provide the optimum load for your specific gun as each gun comes from the manufacturing process designed to meet specific not-to-exceed standards. And, there are variances between guns as they are produced.
As the first step in reloading is safety and knowing the characteristics of ammo and gun, knowledge is important. That knowledge is gained through reading and constantly referring to reloading manuals. The major bullet and powder manufactures publish reloading and reference manuals.
Should you decide to enter the hobby of reloading, there are some steps I recommend.
1. Make a list of the calibers of ammo you expect to reload. Then, begin saving the shell cases matching those calibers.
2. Buy a reloading manual. Lyman's 49th Editor is an excellent resource for description of the steps involved. And, one manual is not enough. My favorite reference manuals are Lyman's 49th Edition and Sierra Bullets 5th Edition. My library also includes manuals from Speer, Hornady, and Nosler.
In addition to the manuals, a separate notebook is recommended for your personal notes as you work through the reloading steps.
3. After studying the reloading reference manuals, determine the type and weight of bullet you expect to be using. This step involves your decision on the expected use of the reloaded ammo and the type of firearm. For example, if you have a 9mm semi-automatic pistol and want loads for general plinking/target practice, 115 or 124 grain full metal jacket round nose bullet is a popular choice. If you are considering ammo for self defense, your choice might be 124 or 147 grain semi-jacketed hallow point.
If you have a .223 Remington (5.56 mm) and your desire is for a varmint hunting load, a popular load is 55 grain jacketed hallow point. However, your specific type of rifle may require a different bullet weight due to the twist rate of the barrel.
As a general rule, the firearm characteristics such as semi-automatic, lever action, bolt action, magazine type, barrel twist rate, and barrel length are variables governing type of bullet used.
4. Once type of bullet is decided, determine the type of powder necessary. Seldom will you find one type of powder that will work for a broad range of bullet weight and calibers. For example, a powder type developed for .223/5.56 is not suitable for safe use in a 9 mm semi-auto pistol load.
At this point, it is important to review your reference manuals to help your decision making. The powder manufacture's websites are another source of information that needs to be reviewed. Hodgdon and Accurate are two powder sources that provide load data for there powder with a variety of bullet types and calibers.
In summary, ammo, type of firearm, and personal technique are inter-related in the quest for accuracy. Key point is to study each point and understand the characteristics of each. The more you know about each, the more successful you will be in achieving your quest for accuracy. Keeping your costs reasonable depends on the amount you shoot and the amount of equipment you buy.
As a cautionary note, there are many recipes for reloaded ammo that can be found on Internet forums. These should be viewed with caution and only used after considerable research to verify the powder, primer, bullet, and caliber are compatible. ALWAYS review the powder and bullet manufacturer websites for the latest information about their tested and recommended loads.
Reloading is fun, challenging, and satisfying. Enjoy your new hobby.
Lyman Products - http://www.lymanproducts.com
Sierra Bullets - http://www.sierrabullets.com/
Hornady Manufacturing - http://www.hornady.com/
Nosler - http://www.nosler.com/
Hodgdon Powder - http://www.hodgdon.com/
Accurate Powder - http://www.accuratepowder.com