Can a 4 prong welder run off a 3 prong outlet?

My Millermatic 350 welder (runs 480v or 240v) has a 4 prong L16-30 plug and I have a 3 prong 6-50 outlet. Can I run an adapter from the 3 prong outlet to the 4 prong machine?

Essentially, can I use the welder without a neutral wire attached?

Also If I can do that, I have 6/3 wire so it has 2 hot, a neutral and a bare ground. If I skip using a neutral, should I use the bare wire or the spare insulated (the neutral) wire as the ground?

UPDATE

I plugged the adapter into the outlet and the welder into the adapter in and the 6-50 male plug on the adapter started smoking. Opened up the male plug and it looks like the wire on the ground prong is the most melted.

I switched the welder on but it didn’t turn on at all, the plug just smoked

Advice? I have no idea what may have happened.

Also I tested the hot to hot on the 4 prong cord end of the adapter and got 220v and then tested the hot to ground and got 110v. Should I be getting voltage on the ground?