Quite honestly I think it's a bit dumb doing this. It's just going to lead to a bit of snowballing for people who are more reliant on special ammo - Even in trials.
Ex: Snipers - typically people proficient in snipers will just immediately get kills by using established sightlines. If you're upping the amount of progress towards a special drop you're going to have someone who gets 2 sniper pops right away/near the start of the match and just be at a strong advantage.
I think this is going to be too much.
Special weapon kills don’t grant progress towards additional special ammo.