The rare first and second pattern AKs of Mikhail Kalashnikov have an interesting story behind them. Would you like to know more?
As detailed in the above by Ian McCollum of Forgotten Weapons, the Type 1 AK (before it was dubbed the AK47) of 1948 used a pretty thin stamped sheet metal receiver that made it economical to make but soon ran into some problems. This, in turn, led to the Type 2 Kalash which used a receiver machined from a solid metal block.
If you are curious about the milled guns– which went into production in 1951 and remained standard until supplemented by the updated Type 3 and finally replaced when the AK went back to an improved stamped design– we have the below video for your approval.