Thanks Everybody,
Actually, I had some trouble with the barrel. This is the second one I have cast. The first one I did with 1 part Portland and two parts sand. I mixed it pretty wet and poured it into the forms vertically. At the end of the pour, as the cement started to set up, the water rose and the cement shrank. I had to keep adding mix and removing water to keep the form full. The end product was a pretty good finish but weak concrete in the top 10" or so. It has cracked but still looks pretty good. It sits on my front porch on a similiar carriage but made out of treated 2 X 4's.
This time I mixed ready mix with gravel. I mixed it a little less wet. The finish is pretty rough despite my "rodding" the form and tapping on it with a mallet. It looks like a "recovered" gun.
The next time, "if my wife allows another one", will be 1 part Portland and 1 part sand. I'll have to mix it wet to get the smooth finish and just deal with rising water and shrinkage by adding more cement.
Any ideas on how to deal with the top 10" of this pour? The mold was made without a "sprue" so the top of the mold is the muzzel of the gun.
Zulu