This would do better in the Tiberius sub-forum.
Which breach are you talking about? If you're talking about the T9, in theory you could mod the barrel (or just get a LAPCO FS ready T9 barrel), and use the FS ready mags.
The T9 FS conversion kit included a new bolt (tapered, non-soft tipped bolt), a new bolt return spring, and the FS ready mag and a new spring for FS rounds. You might be able to get by without the bolt and springs.