Hey there KevinM, you're most welcome.
I'm not at home as I respond to your question and comments, so I don't have access to my load records, but I am quite fond of Blue-Dot for hi-pressure handgun loads, including .44-mag, .357-mag, and .40-S&W. I tried it out in super-lite .38-spl. and found it needed the higher pressure to burn, so it is NOT my "all around" perfect powder, but it does make a sweet mid-range to heavy .44-mag load.
For sizing, I always select and size a cast bullet to be at least 0.001-in. LARGER than the groove diameter of the firearm I plan to shoot the bullet through. It can be very difficult to size very hard gas-checked bullets that cast at .431 or larger down to .429 in a standard sizing press. So, sometimes the bullet mould and design of the bullet will provide some level of motivation to keep the bullet diameter rather large, too.
Of course, there is an additional 'factor' that you must deal with in your model 29 (or any other revolver) and that is the chamber -- or in your case, 6-other chambers. In a revolver, each cylinder throat should be dimensioned 0.001 to 0.002 inches larger in diameter than the groove diameter of the barrel. However, the manufacturers can't seem to get this right every time -- I personally know of RECENT problems with Rugers and Colt in various calibers.
If your lucky, you will find your cylinder throats on the model 29 will measure 0.432 to 0.434, and the groove diameter of the barrel will be 0.429 to 0.430 -- if so, size your bullet to 0.431 and have fun. If your cylinder throats are undersize, you can have them 'honed' to an appropriate diameter for relatively little cost. (I did one revolver myself; it isn't too difficult, but of course you can go too far by removing too much steel, which is a bad thing).
The good news is that oversized cast bullets generally perform well in revolvers when the chambers are properly honed to accept them. The worst case scenario is to have a cylinder that is way too big -- several older .45-Colt chambers were cut with throats at 0.456 or larger, and had barrels fit with groove diameters of 0.451 to 0.452. This will almost always result in very poor accuracy, and can also contribute to leading in the forcing cone area.
There is some very helpful info on the Alpha Precision pistolsmithing website (pistolsmith Jim Stroh out of Georgia).
My preferred sized bullet diameter for .44-mag is 0.431 -- but this may not be ideal for all .44-mags. My preferred .44-40 bullet diameter is 0.429. However, I also know of firearms that won't even chamber cartridges loaded with these bullets, and even if they would, they would lead the cylinder throats with only a few shots fired. So, you've got to match the bullet diameter to the cylinder and groove diameter of YOUR firearm.
Remember to work your loads up gradually, especially while testing various bullets. Hope this helps; good luck. --CC
