Back in the 1980s there were two revolutionary target rifles that immediately raised the stakes for competitors at the top level. One was the Walther LGR, and the other, the Feinwerkbau 300, and the reason both were so revolutionary was that they were the first high-end recoilless target rifles on the market. Before then, target guns were mainly refined, low-powered version of the same guns used by field shooters and hunters with target stocks
In a way, the LGR was the more futuristic gun, as it used a single-stroke pneumatic powerplant, something that other gun makers didn’t pick up on for another decade. But the Feinwerkbau was the far more successful gun, and it used a unique- yet time-tested- system to achieve recoilless operation.
Starting in the late 19th century, the makers of artillery discovered that they could mount bigger guns by the use of a sliding, recoil absorbing carriage, and that’s exactly what Feinwerkbau did in the 1980s. The receiver and barrel of the 300 wasn’t fixed, but slid back and forth on rails. It didn’t slide far- but it didn’t have to counter that much recoil energy.
After cocking the spring mechanism of the 300, you tilt the rifle forward, and you can feel the action slide forward a fraction of an inch as it locks into battery. On firing, the action and barrel move slightly backwards. It’s less noticeable than you might imagine, but it’s enough to make shooting completely recoilless.
The 300 revolutionized target shooting, and before long every competitor needed a 300 to be competitive. Other companies started making recoilless rifles. RWS designed a dual opposed piston system used in a number of their competition pistols and rifles. Others came out with CO2 systems, then single stroke pneumatics, and finally the compressed air systems that now dominate competition at the highest levels.
Since the 80s only two other rifles have used the recoiling receiver system. One was the RWS/Diana model 54 rifle, which was a modified version of the popular high powered RWS 52. It was not a terribly successful gun (especially compared to the 52) and was plagued with mechanical problems. It didn’t last long in the marketplace. More successful has been the Chinese-made Tech Force BS4, and not surprisingly- it’s an exact clone of the FWB 300.
The 54 is indeed still in production- see comment below- and here’s an interesting site on the 54 from an owner who’s done a number of tuneups to his: