Yeah, semi-auto doesn't jive too well with the Nelson design. However, PA (pneumatic assist) does! Basically, the pump handle actuates a 3-way (or is it 4-way?) valve which in turn operates the ram which moves the bolt. Timing is a non-issue. Sure, you still need to move the pump handle, but imagine a 1/4" (or less), nearly effortless pump stroke! For some excellent examples, go to
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