There are more reloaders on the market - than the one in your photo attached....which looks like the HKS version....
depending on the model of your gun ....you can try Safariland or Jet.../ I like them both way better than the HKS speedloaders...with the Jet being my personal favorite in a K or L frame S&W 6 shot revolver...
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Capacity is an often debated issue on "Defense" ...but to me, a good Defense gun, is the gun you shoot the best - at the range that you intend to defend yourself ( 3 - 24 Feet probably )....
So you need to practice with the gun - firing quickly double taps, triple taps - and some reloads...and whether its a revolver or a semi-auto is probably irrelevant...if you can put shots on target consistently that is the key ! So go to the range and practice ....ideally drawing from holster, or shooting from low ready or whatever....( draw from holster and trip taps under 5 sec is probably ok - especially to start ) ....but if you're not 99% in that triangle between the nipples and line to belly button ...you have some work to do. I'd forget about the lasers - and all that stuff....it comes down to whether you can shoot the gun you've chosen or not.../ and .357 Mag is just fine - if you can shoot it well.
Then work on the reloading...and I think Mike said above ...last shot - to reload and 1 shot was around 4 sec ..../ that's a good goal.
One of the drills I like is -( draw from holster - a double tap - reload - another double tap ). Probably start at a 10 sec goal ( for the whole drill )....run it twice at 9 Ft, 12', 15', 18', 21' and 24' - so that's 48 rds ...or almost a box. In a revolver for this drill ...it depends on what fits your hands the best - but I like a K, L or N frame S&W in a 4" in .357 Mag...4" gives me a decent length of sight plane...and K, L or N frame gives me enough weight to handle the .357 mag ( K frame mod 19 or 66, L frame mod 686 , N frame model 27 ...)...but you should shoot what you like, and what fits your hands ! If this revolver was my primary carry gun - or my night stand gun ....I'd run this drill at least twice a week ....3 or 4 times, per range visit....until I had the muscle memory down to a point where I was really consistent on time and reload competency. ( and its fun !! )...