material question

First a \"Hello\" to everyone, rather new here been lurking for a while.  I have the plans for the RGG gun and was wondering since I have built several steam engines and also a 5 cyl. radial, and all out of aluminum and have a big supply of it.  Can some of the parts like the side rails, front bow, yoke, front barrel plate, tripod etc be made ouf of aluminum. Was concerned about strength. This gun will not be fired much after the initial test to see that it works. Yes, understand that barrels and rear barrel plate and such needs to be steel.  Was wondering what others opinions are on the prior mentioned items as if aluminum would be ok.   Thanks in advance for any thought and help.

The yoke needs to have some parts like the hinges, and hinge blocks attached to the yoke by silver soldering them to the yoke. If you can come up with another way to attach them like welding, the other parts could be made from aluminum then blackened. The cocking rings, cam, bolts, shaft, carrier block, rear barrel plate and the crank should be made from steel.
 The reason I think that RG-G used brass and steel was to keep the design more original and to scale.
 Awhile back, cutter made a RG-G with lots of aluminum frame parts on his without any problems.
bruski