The TMX came with bottom thread tubes. The back boring is likely to cause problems with standard tubes. Post a picture here, someone is sure to help. You'll need to measure the bore to find what you really have.
That's why I said "factory 2nd generation". Briley is an after market choke maker, they can categorize anything they want. But if you are buying choke in the picture, from Perazzi, their dealers, or me, you better order 2nd generation.