During the time the 177 springers were getting up there in speed but not powerful enough for 22, Beeman came out with the 20.
Seemed logical I suppose but I think it was more about Beeman making a buck since they're weren't really all that logical. Lots of
people wanting the best/latest stuff and if Beeman said it was the best they bought it. Plus all the 20 pellets he sold.
Generally 20 doesn't really have much of a place. The heavier pellet needs a larger area for the air to push it or it never gets up to a good speed. This applies to all guns but especially a springer. Even firearms jump from 17 to 22, and firearms like to offer a ton of calibers and a zillion variations of each cal. Like how many 22's and 30's are there?
As for the Sheridan; I think it was the same deal, they wanted a gun that made more power than 177 could provide, but that gun was too weak for 22. Mostly I think they wanted exclusive pellets to continue profits after the sale. Their pellets sucked btw, but you had no choice until Beeman came along. I suppose if Sheridan made good pellets their gun it just may have been king of the hill for decades.
As for a new gun, I'd get what best matches what you want to kill, and penetration is imo not the deciding factor since many end up blowing right thru small game as it is, and bigger stuff you probably shouldn't be shooting. Generally I have springers and prefer a gun that can shoot 900+fps, so if a gun is too powerful for that in 177 I go 22. If it's too much for regular 177 pellets but not powerful enough in 22 then I just use heavier 177 pellets. That narrow niche would be where a 20 would fit, but it's still solved with a pellet that's likely still better for any job. Basically I end up with 177 for most everything, and 22 only in the most powerful guns. Lots of people like 22's in the 650-750fps range but I just don't like the trajectory. Btw, when the mfg says 950fps in 22, it generally means reality is closer to 700.
If I want stopping power for whatever then I use a hollow point, specifically the H&N Crow Magnum which will open larger than 22 so it effectively replaces 22 imo. A 22 Crow Mag won't work in a springer as a general rule so they can't play catch up.
Btw, many guns you can simply buy the other caliber if you want to see which you prefer, but look into it first. Like a Crosman is super easy to get and very cheap, but not good quality. A Weihrauch shouldn't be too hard to find and simply more $ which is the quality, and well worth it. A Diana barrel is twice as much as a Weihrauch but not nearly as good quality. A Gamo can be expensive and only sell to an FFL. Many other guns you can't get parts at all.
If you want a PCP gun then that all changes b/c they have more power to throw around and unlike springers they work better with a larger caliber. So for pcp I'd probably consider 22 a min size. Very effective and popular size btw and for good reason, but many want a little more and get 25 or larger.
