I have an older Browning Bps Trap model. The barrel is labeled 2 3/4 inch shells with a fixed choke (not the changeable invector type). Can I put a different barrel on it from another 12 gauge field model that is labeled 2 3/4 or 3 inch shells and has a fixed choke? And then can I safely shoot both 2 3/4 AND 3 inch shells? So, then are the receivers and action the same on the trap model and the regular field model?