My son had an AA .35 Rem bbl and it fit perfectly on his blued frame. It was not factory modified. The pin was a tight fit though. We wrote to the TC factory and they told us that some AA bbls will fit blued frames and some won't. They also said that if it fit and locked up, it would be entirely safe to fire it. He has had it for many years and has fired it quite a bit.
Gary :-)