Yes,you are right..The mass of the Guide Rod is a moving part....The first time Mr.Mann use the groove in the Chamber.. Year 1920..Thank you very muchThe mass of the recoil spring guiderod gets added in as it reciprocates with the slide.
That slide mounted hammer is interesting. Depending on the cocking geometry it could add a bit to
what is a delayed blowback action. The fluted chamber has been used to good effect
by Hk, and with a bit less success by Automag.
Interesting design. Best of luck bringing it to market.