Triac Switching circuit with Optocoupler
You need to provide more info. I feel you are misinterpreting the situation at hand. Assuming you are right, you will run into other problems than the circuit:

1) Supply: I could find only 4 triacs which meet the current requirements:



2) Heating: 50 A is a lot of current. Triacs will have a voltage drop across them when conducting. Approximately 1.3-1.6 volts. At 50 amps, you will be dissipating a minimum of 1.3x50 watts = 65 watts. This is a lot of power and you will need beefy heat-sinks with active cooling to get rid of this heat.

This video shows a guy making heat sinks for high wattage LEDs. Your case is more severe because LEDs convert some power to light. In your case, whole power is being converted to heat. 

I read your comments on the other answer. No, R and C values are not the only difference when you are controlling 10 vs 50 amps. Snubber design is a topic in itself. However there are many things to take care of, especially the triac ratings and thermal design of the entire setup.