Original Mamba manufacture and 'finish'!?

Wow, the guys were in a rush

How it functions is what counts, time is money on a production line, i.e. maximum throughput per worker and probably no time for high precision work on what was probably a conversion job on standard inner barrels from an outside supplier and done on a small scale basis at first. Later guns may be better if machining was done on an automated basis to improve the airflow or internal breathing. Mamba guns looked like they used Omer handles (Tempest and Skorpion style) in their final models. Possibly someone else did further work on the gun as well, it may have been modified after it was purchased. The inner barrel has been spun around in a lathe with abrasive or emery paper/cloth wrapped against it to remove the sharp edges on the newly opened out slots.