air rifle breech question???

i was wondering something- i saw a disassembly of an Evanix AR6, and it looks like the breech was made to slide over a main tube, like most traditional air rifles…would that really work, if the tolerances were really close? forget about other means to secure the breech…im just wondering if the idea of a slip on breech over a main tube would work. I.E. no physical transfer tube, just a tight fitting breech, w/a hole where the transfer tube would go…is that possible?