I have an extra side folding stock for my MP5. Will the HK53 buffer fit/work in this stock, or do I need to purchase a new stock for this?
What folding stock do you have? What 53 buffer do you have? In any event, the urethane mp5 buffer is not adequate for the 53. The 53 should either have a mechanical buffer in the stock, or a mechanical buffer in the carrier ( true for a lot of clone 53 built with 33 parts kits ). It has been well debated, but imo if you have a mechanical buffer in the carrier, you need a metal backplate for it to contact. It is not safe to let it wack a polymer backplate.
I have fooled around with many options for this. While not the prettiest. An ACE adapter in a steel backplate with a Stormwerkz hinge and a ACE skeleton stock is really solid.