they were put on the Schmidt-Rubin K-31 rifles for the Swiss army in WWII.
The K-31 is unique among rifles in that the cartridge (7.5 X 55mm) was designed first, and then the weapon platform designed around it. In fact, the very name Schmidt-Rubin is a reference to the cartridge designer, Eduard Rubin, and the action designer, Rudolph Schmidt. The cartridge has a 'wax' ring sealing the bullet to the case, which turns in to a lubricating/sealing gas when the round is discharged. The bullets are nickel washed to improve in-flight stability and penetration. The rifles were issued to individual soldiers for their entire service life, and the soldiers would put a tag with their name, their unit name and address under the butt stock plate. Many of the bulk rifles still have those tags. Kinda cool.
The rifle is easily identified by its 'straight-pull' action. It's a bolt action that the operator doesn't have to rotate. I could go in to all the engineering details (like the little thing sticking out from under the barrel is a way to stand 3 rifles up together), but it's a marvel of precision, simplicity, reliability, and accuracy. It has a sight cover, detachable magazine, and that big ring on the back is the safety. The safety is completely silent, can be operated wearing heavy gloves, and a soldier can work the action without raising their head. Which means they don't have to expose themselves to counterfire when re-chambering a round. When the Swiss dumped their armory, these rifles could be had for $89. I bought one because it was so cheap, and took it to an outdoor range. After two sighting shots to adjust the sights, I put 3 consecutive rounds on a 10" target from 500 yards out, open sights on a bench rest.
Shortly before World War I, the German Kaiser was the guest of the Swiss government to observe military maneuvers. The Kaiser asked a Swiss militiaman: 'You are 500,000 and you shoot well, but if we attack with 1,000,000 men what will you do?'
The soldier replied: 'We will shoot twice and go home.'"
The 'pioneer' bayonets were only issued to very select units. Engineering troops, mounted artillery, saddle makers, and
blacksmiths. Basically, troops that would need to cut brush or make staves as part of their combat role.
I thought the fact that it's a rare piece that was only issued to blacksmiths would make
@Bushkill Blades' nipples firm(er).
The Krauts also had a bayonet with a sawback, but once the tide of war started turning against the JewKillers, German troops started filing off the sawbacks in case they were captured...lots of reports of liberated citizens using those bayonets to remove pieces of captured Nazis.