I've been chewing on some ideas I've had for awhile now, one of which is a firearm system. The concept behind this idea is that every time you shoot, you are creating muscle memory. Do it long enough, and you could work your safety without looking or reload without taking your eyes off your target. If someone was to hand you a new firearm however, the first few times you were to use it, you probably would be at least slower, if not unable to work the safety or reload without visualizing the action. At cross grain to this idea is the thought that no caliber is a silver bullet. Rather each caliber is a tool in your tool box or club in your golf bag. Selecting the right one for the job is open to a debate that I don't want to get into here. Lets all agree that each caliber has an appropriate use and going beyond that might mean that one should step up a caliber, or even down as the case may be. So how does one get around this? If I,for instance,need to go up a caliber, that often means a different firearm is going to have to be used. One that may have different ergonomics, or possibly even a different action. The feel is going to be different, the safety might be in a new spot, and reloading could be the opposite of what I am used to doing. In other words, the first concept is at odds with the second, unless we are purposeful in our weapon selections. Keeping the actions similar is a good start. Marlin for instance offers multiple lever actions in calibers from .22lr to 45-70 and beyond. One could use a .22lr for small game, pair a .357 mag with a revolver of the same caliber for home defense, and use a .35 Remington for larger game for instance. The rifles would be different in size and even in reloading, but would be similar enough that one could probably overcome the problem as presented above. I believe Savage offers a similar option if bolt action is more your style. Taking it further, one could do a similar thing using multiple companies that produce a similar platform. The AR15 style weapon system is one of the first ones that comes to mind. A pistol caliber upper could be used in conjunction with an insert and a standard lower. Add in the upper that it replaced, possibly another in 6.8 or 300 blackout, and a version of a .22lr conversion kit and you have a multi caliber weapon based on a single lower. Or you could by multiple ARs in each of the calibers mentioned above. Cost does enter in here at some point. To take it further, one could also purchase an AR10 style rifle in .308. This would offer greater range in a package that offers the same muscle memory that you have already gained from using the AR15 platform. If the AR platform is not your style, another similar option could be cobbled together using M1 carbines, Ruger 10/22s and Mini 14s, and some commercial variant of the M14. I believe that the charging handle for each is on the right side of the weapon and that, with the exception of the 10/22, one needs to use a rocker action to seat each mag. Again muscle memory is consistent and the ability to change between each caliber in your tool box should be easier to do. Glocks, S&W M&P, and 1911 style pistols come to mind for pistols. Each are available in multiple calibers and .22lr conversion kits are often available. For revolvers, Ruger and S&W offer multiple calibers with a .22 option on a similar sized frame. The ultimate might be the Thompson Center series of firearms, ones that offer multiple options for calibers in both pistol and rifle configurations that fit the same frame. I am sure ther are other options that I am not aware of. Might be something to consider as each of us looks to increase not only our firearm collections, but also our abilities to use them successfully. Just some of my thoughts.