Always a good idea to check it...but I can tell you from experience with 311 - 19 bought at multiple places that it does not have corrosive rounds.
For anyone testing arounds, I'd always suggest isolating rounds and not mixing them, and having a scheduled and regimented checking methodology...
For instance...if I just got a batch of 311 - 21 (let's say)...
I go clean my 7.62x39 rifle say an SKS - I clean the action, barrel, gas tube, piston.
Then I only shoot the 311 - 21 rounds only (not shoot anything but that during the range trip), and only those rounds with the exact same headstamp.
Go home, put gun in the safe, check on it a few days later.
Check especially the gas tube and the piston rod a few days later. Check barrel and action.
If it is just the regular black carbon build up, clean all the components as usual.
Then repeat, testing another batch. And perform the same inspection / checks after.
If when checking the different parts you see corrosion, orange rusty stuff, pitting, etc. - run hot water (boiling let's say) through it and then clean and lube as usual. And obviously note the ammo you used contains corrosive rounds.
I just ran another 80 rounds of 311 14 white box through my SKS this afternoon at my club. Previously I have run about 940 rounds of the same stuff (311 14) through it with ZERO problems. I don't expect a problem in a couple of days time when I check on the components.
