20b irons help
 

so my question is are all the irons different in the 20b or can rew irons be used. I know big mid iron is not the same but what about the other 3 ???

you can use the 13B cosmo irons, but there are a few holes that need to be machined, because the 20B uses bolts thru the front iron, and some are different sizes from the 13B to the 20B