That is an clever solution. It actually looks like it could work. I am wondering if the rifle had a pinned barrel if the pin could driven out and replaced with a removable pin? I will have to find a cheap used rifle to play with. Savage does basically the same thing with a key way and a barrel nut on their 64 take down. Same with Henry and the AR7. The Promag Qbd stock does this with a 10-22 only it uses an under lever that hooks into the barrel notch.
If Ruger had used the 10-22 barrel on the RAR they would have another Lego gun. There are several companies making 10-22 actions. If one of them came out with a bolt action that would take the 10-22 barrels I think they would have a winner.
Older Ruger 77/22 rifles, like those from the 90's, have the same type barrel attachment system as the Ruger 10/22 still does. A few years back they went to threaded barrels/receivers.
My Ruger 77/22's, both of them .22 LR and .22 Magnum have the clamped on barrel and might be a good place to start for a bolt action take-down version.
Barrels pinned to the receivers, like most of the Marlin, Mossberg and Stevens versions are quite a bit of fun to remove once the pin(s) are driven out. Some do have two pins. When the pin through hole is drilled, a burr is rolled over on the off side of the hole after the barrel is force driven into the receiver. On the Marlin .22 barrels, to replace the cartridge guide, the barrel must come off the receiver, which has been force driven into the receiver and then pinned.
Part #89-11 is the cartridge guide and can only be replaced with the barrel removed from the receiver. This part fits into the slot in the rear barrel shank. Part #89-5 is the barrel to receiver retaining pin. The hole for this pin is drilled after the barrel is pressed into the receiver. The same process is used for most of the low-end priced .22 rimfire bolt action guns. The drilling of that hole causes a burr that tightens up the union of barrel to receiver, and the barrel can only be removed using a fixture to force press the barrel out of place.
Every takedown .22 bolt action and even many of the single shot .22 actions use a half thread mating of the barrel to the receiver, so it would be quite a feat for anyone to get a repeat fit properly, unless it's very tight.