During the Belarusian MILEX 2017 expo, Russian ORSIS introduced a Mosin-Nagant rifle chassis called “ORSIS Mosin”. The chassis features a folding and adjustable stock as well as short quad Picatinny rail section in the front portion of the forearm. There is also some sort of a side mount for the scope.
The Mosin-Nagant rifle with this chassis installed weighs 5.8 kg (about 12 lbs 13 oz) and has an overall length of 1264mm (about 50″). The tech specs are probably stated for the 91/30 rifle. The magazine capacity is 5 rounds. Presumably, they mean the original capacity and there is no information whether it takes Archangel/Promag magazines or not.
The main and obvious advantage offered by such chassis is that they convert usually pretty capable military surplus rifles into a more modern rig. Also, most of those chassis don’t require any permanent modifications to be done on the rifle. They basically just replace the original wooden stocks.
I think the next most important part is the price. If these chassis are not affordable enough then they have little to no value. If the price of chassis makes the whole package become as expensive as a new modern rifle with comparable ballistic characteristics, then why would anyone buy them?
ORSIS hasn’t announced the price and availability information yet.