You're absolutely right, Sonny. Please don't base your production - or even make blanks - based on the response you get on this site.
I've been making handmade 15 round, high-end burl, laminated, and hardwood cartridge blocks for about 20 years for my own use in IBS Score Benchrest competition. Very labor intensive effort, especially the finish work and clear-coating. Along the way I sold a few to friends, who urged me a number of times to make some to sell. I finally took their advice and made up about a half dozen. I went on the "General Topics" Forum, posted photos, and gave a little background on them. The response was great with more than a few posters interested in buying.
Fast forward - I moved the effort to the classifieds, re-posted photos and prices, and sold exactly one (1) block. And, even that was not a 15 round, but a custom 25 round one. After a few weeks and no further responses, I took the ad down. Lesson learned: A good idea-product is not necessarily a profitable one and/or worth the effort.
Now - if you are determined to do this, just make a few for a widely used case diameter (.473" maybe) and put them in the classifieds. It won't take long to find out if can sell enough to make it worthwhile. Worst case - you'll end up with them for your own use. Good luck.
Chris Mitchell
A LOT OF GUYS MAKE THAES BLOCKS AND THAT IS WHY YOU COULD NOT SELL MANY, lots at major short range br, Sinclair’s and so on
Many can be purchased for 75 bucks so you may have some high end in your mind but beauty is in the eye of the beholder in reguards to wood samples. Jeff