The lock-back mechanism is a well-known type and it can be found on an incredible amount of knives in history. It is a decent mechanism and it is a full contact type and by that I
mean it is a design that incorporate the spring and lock simultaneously. It is also fully tight and this is also into my full-contact mindset. The strength of this type depends on the precision and dimensions of
the materials. With pressure against the edge then the back of the blade and tang rest against the contact areas on the spring and can take tremendous pressure if the design and rivets are according. There are several similar designs and a huge variation of
Against the lock when backing out of a cut it is a safe mechanism. I would say it is smart to avoid any pressure against the lock unnecessary and make a habit of this. When
you apply extra pressure against the lock then the strength of it depends on the spring, cut section of the tang and precision of everything. It is not only what many believe that the cut section of the tang hooks into the counter part of the spring avoiding
it to fold.
At one point the lock-back mechanism may collapse. In my experience it is the precision and the depth of the cut section in the tang and counter-part on the spring that are most
important to avoid the collapse or folding of the blade. The precision of the design and some spring tension is important. The precision of the complete design and mechanism will distribute forces on several contact parts and make this mechanism a safe one.
The durability on the lock-back mechanism depends on maintenance, use
and materials. Maintenance from time to time will prevent unnecessary wear on the mechanism. In my experience some oil on the blade so it moves freely opening and closing. Some also use a very small amount of oil on the lock. The surface on the spring and
tang may influence the mechanism. In the design on lock-backs there are many times taken into consideration the durability and that it will continue to be safe from wear. It is fully possible to make it able to
continue to lock even with or after wear of the contact part.
It is important that the mechanism is free from dirt and substances. Next is the design of the cut parts
and counter-part in the spring. This is very important because the design and angle of this can very much influence the safety when engaging it. It is about distribution of forces, precision and angle that will prevent collapse. Lock-backs are many times under
estimated today. If it got all the correct design features then it will be safe. Lock-backs can become a very advanched mechanism with small and extra design features and angles. It can be made to press the tang and spring together in an advanched way.