Unscrewing the gas plug and removing the five position regulator completes the stripping of the gas system.
The gas system of the SA80 is directly derived from this, the differences on the SA80 being that the regulator is integral with the gas plug, and that the gas system vents to stop the rearward travel of the operating rod. On the SVT 40, the rearward motion is stopped by a shoulder on the operating rod, so the only gas to escape the system is that which gets around the head of the gas plug. This means that the SVT 40 gas system is far cleaner than that of the SA80, since far less gas passes through it.
For the sake of interest, the tool roll contains (top to bottom): gas plug and gas regulator wrench, cleaning rod handle, Jag, pick (for getting crap out of bits), foresight/stock bolt key and guide piece. (apologies for the focus)
The rear sight is typical Mosin-Nagant type, as is the post and globe foresight.
Now, why was this marvellous piece of kit not liked by conscripts? It is this author’s opinion that it is a training and motivation issue. this rifle is far more complicated to operate, strip, and clean that your bog standard Mosin-Nagant bolt action or PPSh submachine gun. Russian small arms ammunition contained corrosive primer compounds, as did British ammunition. This starts corrosion extremely quickly, and all gas affected parts have to be cleaned with water/alkali solution, otherwise they rust. Essentially, if you shoot your rifle at sunset and do not clean it, by sunrise the gas parts will have stiffened due to rust, and there will be rust in the bore.
The gas regulator is very small and fiddly and has to be set by eye, an extremely difficult task in the dark – assuming you have not lost the damn thing. In addition, as standard only three magazines were issued, and the charger loading functionality is poor (even worse than on the Mosin-Nagant rifles)
If all of this is not done correctly, the rifle won’t work properly. Hence its reputation for unreliability amongst the conscript troops. It was, however, well loved by well disciplined and well-trained troops, who could probably scab buckshee extra magazines. The Boxies loved it!