Yeah, post-calibre firearms are pretty much just better (hence crossbows not seeing much use on the modern field of battle). Pre-calibre it's a little stickier, because either reloading or ammunition manufacture becomes more complicated.
My apologies, but I'm slightly puzzled by one thing. What do you mean by "post-calibre"? Is calibre not simply a measurement of the internal diameter of the barrel? Are you referring to standardization of calibers in gun design?
But, one fun fact: one of the advantages of early firearms was that ammunition was simple as all get-out compared to the alternatives. You could literally load rocks into some early cannons, and musket balls were literally just a round ball of lead. You didn't even need to get the size all that close to the actual caliber of the gun, as long as you were close enough that it would drop into the barrel during loading. Contrast this with arrows or bolts, the former of which in particular required a proper expert fletcher. Gunpowder was more expensive, but still could be mixed up in bulk at a specialized mill; the rise of the arquebus is tied not only to metallurgy and refinements in design, and not only its effectiveness, but also the ability to churn out corned gunpowder (for those readers following along, gunpowder mixed in a liquid to avoid explosions which resulted in a paste called mill cakes, then reduced to pellets called corns by analogy to cereal crops) like...err, hotcakes. Bullets don't really start to resemble those of the modern day even in shape alone until the 19th century, the Minié being the most famous, as far as I'm aware from my admittedly quite limited knowledge.
EDIT: Trimmed a bit at the top, leaving only my question to Arx.
That said, regarding pikes as top dog, don't underestimate cavalry on the battlefield. Heavy cavalry would rip apart unprotected soldiers or formations that weren't in order (people always cite Agincourt or more rarely the Golden Spurs, but never Patay, and before they adapted, knights in the Western European tradition proved devastating in the Levant - when it reached the battlefield - where tradition favored light cavalry in a secondary role). Light cavalry were your eyes and ears on the battlefield, as well as skirmishers to harass the foe. Once you routed an enemy, too, cavalry was your key instrument to make sure they didn't simply reform ranks an hour or two down the road, as its superior mobility allowed you to run down foot soldiers. Spears in good order could stop a cavalry charge cold, but all too often, the point of the heavy cavalry was combined arms - other forces, such as other foot soldiers or archers, were utilized to disrupt the enemy's formation, then cavalry exploited the gap.