Thanks again to John Eilertson, the master resurrector of dead threads for allowing us to take another step back in time to 2009! Well, to the subject at hand:
Largest Gun - 155mm Howitzer (no, I was not FA, but most officers were cross-trained in disciplines outside their primary MOS). Largest MG - M2. 50 BIG. Largest rifle -was 460 Weatherby Mag in a Weatherby Mk V. Largest shotgun - 10 Gauge side by side double, especially since it would fire both barrels simultaneously when we first got it -the 3 1/2" magnum loads! Largest handgun - my. 500 S&W, 8 3/8" barrel, heaviest kick and muzzle blast king - 4" S&W 500. Largest BB gun - Daisy Model 94, smallest BB gun - Daisy Peacemaker (copy of a Colt SAS, between the two, I was the best-armed 10 year old in the neighborhood, but that was a long time before 2009!
Don't worry John Eilertson, we're still working on that time machine to rescue you from the time warp - just haven't heard back from H.G. Wells yet.