Think: A close-fitting sleeve about 6 to 8 inches long over the barrel just forward of the receiver.. This sleeve is then “bedded” into the fore-end / bolted to the chassis, etc, but the receiver “semi-floats” in the “stock; maybe with some synthetic (soft) damper pads. Reducing the length of barrel that is free to vibrate will cause that vibration to occur at much higher freqencies and smaller amplitudes.

A prime example of something along these lines, in actual service use, would be the Finnish TKIV-85 sniper rifle which is built on a Mosin Nagant action. Don’t laugh, because they have a reputation for exceptional performance.

Interestingly, When the Chinese were cooking up a replacement for the basic old AK, they came up with something called the QBZ-95. This beast is a Bullpup firing the (also Chinese-designed), 5.8mm cartridge. This is also “barrel-centric” in its design.

Other “barrel-centric” designs include the classic Patt-53 Enfield muzzle-loading rifle; no receiver at all, just the classic “Lock, Stock and Barrel” This was the start of serious, large-scale, military “long-range” shooting; 600 yds plus.

Aniher trick I saw done with light-barreled AR variants, decades ago ws to replace the basic flash suppressor with one that included an extension tube that extended clear of teh barrel and seated against the front of teh front-sight post.This was torqued up, essentially stiffening the actual barrel and damping muzzle “whip”. You could set the “tuner” to work with several ammo types; very useful., especially if you recorded the torque (and sight) settings that produced the best groupings at a particular MPI. So, instead of having to brew a special load for each of every .223 rifle in the safe, you had ONE or maybe two and tweaked the barrel accordingly.

Just sayin”…..