I'm sure we'll see your uncle on the Panzerketten forum soon!

As for the ricochets, it's probably because the inner barrel wasn't lengthened. When the round comes out of the stock barrel it tends to arc and it would hit the inside. If the velocity of the gun was increased and the muzzle brake reinforced, ricochets would occur less and not as likely to blow the brake off! If you're not going to shoot, don't worry about it.
Do you have any plans to add the little handles along the fender and storage bin sides? [link=http://www.rcuniverse.com/forum/m_6413851/anchors_6413851/mpage_1/key_panzerkampfwagen/anchor/tm.htm#6413851]M26A1 Pershing - USMC Korea - Build [/link]