I'm 6'2" but don't have big hands. I have three hammerguns. My method for cocking both at the same time is simple. When hunting flushing birds I carry the shotgun similarly to port-arms, muzzles up of course, hammer spurs pointed back towards my chest and with my thumb across both hammer spurs. All three of my guns have the hammers fairly closely spaced, not wide apart. When ready to cock, a simple leveraged movement done by pushing the forend hand away, while at the same time sweeping the right thumb back, cocks them both. Works for a Rem. 1889 12 ga., a San Georgio 12 ga., and a Manton percussion m/l 16 ga., and all part of the mounting move. When using them for doves or ducks they are fully cocked at all times while I'm on my stand, and I am still, not walking.
External hammers that are cocked are not AS "safe" as a gun with a hammer block safety, i.e. IMO they are more likely to discharge due to a fall, etc. .........but they're safe enough, in some conditions, to remain fully cocked. Horses for courses. No reason to try to apply either method to all conditions. Most boxlocks' and sidelocks' safeties don't block the hammers anyway, they just prevent movement of the triggers. In that regard there's no difference in the "safety factor" of a internal hammer gun and an external hammer gun. Either could possibly slip out of bent in a fall, according to the amount of sear engagement and the angles of them.
