What are your experiences on riding with a fixed cog rather than a singlespeed freewheel on a freewheel rim?

I know there are specific rims with two sets of opposite threads for fixed cogs, but I only have the normal FW hub. I have an old BB lock ring that fits over the hub after the cog. Will this hold?
I'm only using this on a junky vintage frame bike I have so I dont mind if theres a chance of it just stripping the threads on the hub or anything.

Thanks.