I'm not a technical expert but hopefully I can offer a little information for you:
'Machine Forging' took over from hand forging as the cost of labour increased and suitable machinery was developed. I would imagine that over time it became possible to produce a more consistent forging using machines that weren't subject to the human vagaries of Monday morning/Friday night etc!
Example of this might be the Greener laminated silver steel that they promoted in many of their late C19th guns.
As to bulging at the choke, we see this a lot nowadays with modern proof testing (in both damascus and steel) and, although barrels that have thicker MWT''s in the area immediately behind the chokes are LESS likely to bulge, wall thickness is most certainly not the only factor.
Degree of choke, profile of the forcing cone from barrel to choke, elasticity/hardness of the barrel material and probably many other factors have an effect.
In fact, in most cases, once the bulge has been knocked down/struck off/lapped out, the barrel passes proof. It has been suggested that the 'working' of the barrel, rather than weakening it as if often suggested, 'work hardens' the metal, putting it in a more 'spring state' which can then react to the proof overloads in a proper way.
It is most likely that reducing your choke constriction will decrease the likelihood of bulging your barrels at the choke rather than increasing it as the bulge referred to is in the area just before the choke, not in choke constriction itself.
