Tri-x 320 is way different than Tri-x 400, as had been said. The tri-x 320 in 220 is the same film as tri-x sheet film. It gives a very different tonal scale, with strong blacks to whites, rather than a tonal scale of grays as with the 400 film. In high contrast light there is considerable danger of blowing out the highlights. Many Tri-x 320 advocates, of whom I am one, use it with a compensating developer such as pyro or dilute HC110. I rate it at 100 to 160 and develop to take care of the highlights.
BTW, the 220 film doesn't have paper backing on the film, only on the leader and trailer of the roll. The film lies flatter in the film plane. This is noticeable when shooting with wide fstops.
The best reels I've found to load 220 film are the plastic reels from jobo. the more macho stainless steel reels for 220 are an exercise in frustration.
Take care,
Tom