Challenge it al you want - choke deals ONLY with patterning. Do not confuse pressures of metallic with shotgun - the two are not comparable.
The choke is the last inch or two of the barrel, the speed is fast, AND the lead compresses to squeeze through the choke - the same with those "rifled"looking slugs - they swage themselves down to go through the choke - if there was a pressure spike, the barrels would be blown apart in a nice kaboom
As to foreend weights, try here
Jim has great mag cap weights for Remington