Well first I was talking At-st the 2 legged Variant I fully agree the at-at could work. But I digress. I could very easily explain several of the guns just off the top of my head. Barrel at the bottom of the cylinder with hammer still on top? Hammer is still used for a double action trigger and is linked to said action but it does not mean that it contacts anything with the firing pin. The firing pin would be lower in the weapon but the hammer could be connected midpoint to a secondary hammer the actually contacts the firing pin. It would be very poorly designed I agree but within the realms of possibility. Barrel in the middle of the cylinder. This is the future again, what's to say there isn't a secondary loading device that moves the round to the center before firing? illogical design yes, but possible. I could do these all day as they are fantasy based. Be creative and remember that hundreds of years have passed, possibilities are endless.