Could the gatling gun used during the civil war which was heavy and large be made into a smaller variant with perhaps 3 barrels for individual use? What challenges would be faced and how can they be overcome
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Let us imagine for a minute that you could build a Gatling gun with three barrels and civil war technology, and that this gatling gun only weighed 40 lbs, as opposed to ~150 lbs+ for the real deal. You still have the following problems.
Accuracy - How are you going to aim it?
Precision - Modern machine guns have recoil absorption mechanisms built into them. The original gatling gun did not. If you fired it while holding it by hand, the recoil would assure that no two bullets ended up anywhere near each other.
Net fire rate is the same as for a rifle - A civil war rifle can make perhaps 4 shots per minute. A gatling gun could make 400 shots per minute? But then how long does it take to reload the gatling gun? The advantage of the crew served weapon is that some were reloading the clips while the gun was firing off a different clip. If one person had to stop firing and reload all 400 rounds...I'm not sure the net fire rate over the course of a several hour battle is actually any higher than for a rifle.