A while back I had the chance to pick up a fairly unique semi auto .22 rifle. It's a Mauser model 105. Don't be surprised if you've never heard of it. Very few made it into the US, and they're not all that common in the rest of the world either.
Sometime in the 80's (probably around 1986?) Mauser purchased the German manufacturing portion of the Voere company. Most of the guns that Voere had been producing in Germany were .22 rifles, and Mauser apparently wanted into that market more than they had been. When Mauser made the purchase, the made a few minor changes to some of the Voere models, and started marketing them under the Mauser banner. The Mauser 105 is one of those rifles, it was based on the Voere model 2005 rifle, The changes that Mauser made seem to be limited to slight variation in the stock, and adding threading (1/2"x20 TPI) to the end of the barrel.
The rifles have 24" barrels and grooved receivers for 3/8" scope rings. I removed the sights from mine (the rear for clearance for the scope, the front for aesthetics) and added a BSA 4X scope I had laying around. One of the big problems that I had with the gun when it arrived was that it didn't come with a magazine, and they aren't readily available. After several weeks looking, I had located one, and it was going to be $90+ $24 shipping from Germany. So I started looking through my box of random magazines, and saw that I had several Bingham model 20 magazines that I didn't need, so I proceeded to open up the magazine well to take the Bingham magazine. With a little work, and adding notches in the appropriate place to the Bingham mags, I now had a magazine and two spares (and about a half a dozen more that can be converted if I need to, they don't loose their ability to be used in the Bingham).
I had an adapter for the 1/2x20 thread pattern that allows me to use my 1/2x28 suppressor on the rifle. I find that I shoot it this way most often. Using CCI standard velocity ammo, it's both accurate and quiet.
One of the things that makes the Mauser 105 interesting is it's simplicity and mode of operation. The rifle has no extractor, and no firing pin. In fact, there are very few moving parts. The bolt is a single piece of machined steel with the bolt handle screwed into the side. What makes the rifle able to be so simple? It fires from an open bolt. That means that when the bolt is pulled fully rearward and locked back, the gun is actually ready to fire. Pulling the trigger releases the bolt allowing it to run forward, picking up a round from the magazine and pushing it into the chamber, as the bolt continues forward, the raised ridge on the bolt face crushes the rim just as the round is fully chambering. The recoiling shell pushes the bolt back. The shell strikes a raised portion of the barrel extension and is ejected while the bolt continues rearward where it locks, ready to fire the next round.
The gun is lightweight, just about 5 and a half pounds with the scope and suppressor, and it points naturally. It's very easy to hit what you're aiming at.
The Mauser 105 isn't the pinnacle of any particular aspect of firearms design or manufacture, It's not the best at anything, but it's good enough at most things that I think it's very nearly the perfect semi auto .22 rifle.
In fact, I like the rifle so much that I bought a second one. I still have the magazine problem with that one, but I'm working on finding a solution that will let the rifle stay original.