If it is a munition snipe then its base performance would need to go up as well? It is only so broken with the 70%+ snipe, not because the rifles are particularly impressive.
Transform them into a light recon team. Camo, sprint, model snipe (what about something like the OST sniper vet round that gives a small stun? No aoe attack tho), maybe decap quicker? They could remain rather cheap if they are not such powerful force multipliers because as is a pair of JLI and a pair of volks is scarier than just 4 volks and is actually better on the munitions... Less powerful apart but devistating together.
Personally I think a price up to 280 is a good start, that and lower the crit slightly, again start with something like 60% and see how those pair of nerfs make them feel. Small steps for fine tuning not sledgehammer nerfs to remove the unit from the game