Let's say you shoot 50 rounds a month (600 rounds each year) from your defensive handgun. This is probably the minimum necessary to maintain proficiency. To increase your skill level by a noticeable amount, you'll need to shoot at least twice that much. This means you'll spend about $600 each year. You can save money if you reload, but time you spend reloading could be spent shooting. There is another way.
Rimfire conversion kits are available for many of the most popular semiautomatic defensive handguns. Most of them retail for around $300, and you can buy 1,000 rounds of .22 LR ammunition for less than $200. By using a rimfire conversion kit for some of your training, over the span of 3 years, you can save a grand or even more—at least enough to buy one new handgun or pay for one night on the town in Vegas.
I've been using rimfire conversion kits as training tools for a long time, but not just because they allow the use of substantially less-expensive ammunition. The recoil and muzzle blast of centerfire ammunition are two enemies of accurate shooting. They can induce trigger jerk and flinching, even with seasoned shooters. The human brain is a magical thing but it can process only so much information, and it can control only so many muscle functions at one time. When stressing your shooting ability through advanced tactical drills that require movement, threat evaluation and unconventional positions—all at a faster pace—the basic principles of shooting often become a secondary priority to your on-board computer. As you struggle to master the more tactical aspects of a certain drill, you often end up missing the target.
When you begin working on new tactical problems, using a low noise and low recoiling rimfire conversion kit allows your brain to devote less of its operating power to struggling with the handgun and more to solving the problem. I've tested this on numerous occasions and found I progress through the more difficult tactical problems if I begin live-fire with a rimfire conversion kit. This shouldn't be a surprise; it's a similar approach to the crawl-walk-run concept of training, but instead you dry-fire, rimfire and then centerfire.
Of course, the problem right now is finding rimfire ammunition. In fact, it's probably easier to find 9mm, .40 S&W and .45 ACP ammo than it is rimfire ammo. But this, like all things, will change, and affordable and easy-to-find rimfire ammo will once again be available. It might not be a bad idea to already have a rimfire conversion kit for your defensive handgun when that time comes.