I know what Roger is saying- there are some guys out there who can shot flint rifles better than most others can shoot any rifle off the bench - indeed, they usually do the same - better offhand than they can shoot off the bench themselves. Taylor is just such a flintlock competitor.
Since I cannot hold a rifle - any rifle, steady, the faster and most importantly, the even consistency of the ignition, the better I can time my shot and therefore hit centre. Timing is involved in squeezing the trigger to insitgate ignition when the sights are coming into the centre. The is important, as if I hold centre, by the time the gun goes off, with the relatively slow ignition of a muzzleloader or even modern rifle, by the time the bullet or ball is gone, the barrel will have moved off the target. With the milliseconds of time involved between flintlock being slower than a percussion, the gun's sights, always moving, move off the target's centre even more to spoil an offhand target - high low or to one side of the actual aiming point. The faster the 'consistant' ignition, the closer that shot is to the exact aiming point, and once one practises enough with a particular rifle offhand, one can time the shot to hit the same place, every time. Timing, is the most critical aspect of offhand shooting - whether it's a muzzleloader or a Swiss butted International offhand rim or centre fire. The most consistant, fastest ignition time wins and that usually includes the fastest barrel time as well. The longer the barrel, the greater to potential for the barrel moving off the mark between ignition and the bullet's departure from the muzzle - this is why most all benchrest barrels are 18" to 22" in length - and they're shooting 3,000fps or more with the fastest, stiffest, modern bolt action rifles made.
For us, with iron sights, it is a trade off between sight radius and barrel time/lock and ignition timing.
We have many strikes between us and perfection, so we must practise with what be brought to shoot - and practise, practise, practise.