My shooting mainly involves .22 rimfire, along with testing various theories concerning this caliber foisted upon the inter-web, and accepted by some as "gospel". Some of the stuff suggested is just too much to chew, let alone swallow, so, I gots to try it for myself, if only to satisfy "that itch". I like to slug the bores of my .22 rimfire rifles to get an idea of what their actual bore size is. The best lead slugs that I could find already are attached to the mouth of a cartridge case: I made up this "inertia" bullet puller from some 1" PVC unions and caps and a ½ inch oak dowel I had laying around. The bottom end of this tool has a gel-type cupboard door bumper in it to prevent deformation of the lead bullet, once the case lets go of it by smacking the puller on a hard surface. I quit counting after removing over 300 bullets with this tool, so I can confidently say it works very well, and most of all SAFELY. One of the bullets is lubed up with vaseline and then shoved into the chamber until it hits the leade, just short of the actual rifling. Of course, the bore is cleaned as best as it can be before pushing the slug through. What this slugging does, is, it will tell you where you have tight, or open areas in your .22 rifles bore. Lead is a dead metal, so once it gets to its smallest diameter in a bore it will not expand when it passes over a more open bore area. Once the bullet exits the muzzle, I'll measure its diameter with a digital micrometer and record that dimension I've done this process even with some of the bulk packaged .22 rimfire ammunition, only to see if I can segregate that ammunition into groups for sizing: This is a "Paco Kelly" tool used to either bump up, or swage .22 lead bullets still in the cartridge case, up or down to specific diameters, as close as I can get to actual bore size from measurements taken after slugging the bore. The tool also is provided with bullet nose altering spuds that can create semi-wadcutter, or extreme hollow points for expansion testing. Does the process improve anything at all? Well, to some extent, yes it does. I can get some .22 rimfire ammunition to group much better after getting those to a more consistent diameter size than just using them as they come out of the bulk box. Now, is this process worthwhile? Only you can decide that for yourself, but I enjoy trying these things with .22 rimfire, so it's fun for me and I get to do even more .22 rimfire shooting when I do this sorta thing.