What is the structure and principle of elastic gun mount?
Before we talk about the elastic frame, we should first talk about the buffer of the heavy machine gun frame,
For example, the sg-43 heavy machine gun of the Soviet Union has two connection points between the gun body and the gun rack, but its gun body is not completely fixed on the gun rack, but can slide back and forth. Notice on the left side of this picture, under the front connection point, there's a spring.
This part with spring is called the buffer of heavy machine gun frame. It is to add a floating sliding plate between the gun body and the gun frame. There is a spring in the sliding plate. When shooting, the gun body floats back and forth on the sliding plate of the gun frame, absorbing and consuming part of the recoil force.
Take another look at sg-43's opponent, the German mg42 general purpose machine gun. The tripod is also equipped with buffer, and the gun body is floating on the gun rack. The advantage of this kind of gun rack with buffer is that the buffer can absorb a lot of recoil force, and the impact on the gun rack is relatively small, but there are also some shortcomings. This kind of gun rack with buffer has heavy weight and complex structure, In addition, after a long time, the buffer spring will lose its elasticity, and the buffer sliding plate will be worn, which will affect the shooting accuracy. When we talk about the gun holder with buffer, we can explain what is called "elastic gun holder". The so-called elastic gun rack is a machine gun rack which has no spring buffer, but relies on the elastic deformation of its legs to absorb recoil force. For example, the tripod of PKM universal machine gun mentioned by the questioner.
This kind of tripod is made of stamping, very light, rigid fixed connection between the gun frame and the gun body, no buffer, when shooting, recoil force is directly transmitted to the gun frame, relying on the elastic deformation of the gun frame legs to absorb recoil force. This kind of gun rack greatly simplifies the structure and reduces the weight, especially PKM has rarely been used in heavy machine gun state, tripod is just a backup, this kind of light tripod has good applicability.