Yep, .429" is the "standard " diameter of a .44 Magnum bullet. What your gun cylinder throats and groove diameter are is another story. Manufacturing tolerances, and what the manufacturer thinks is best will get you anything from .428" to .432" as .44 Magnum dimensions. I have 5 .44 magnums, three have groove diameters of .429", one is .430" and one is .432". Fortunately my revolvers have .430" - .431" cylinder throats and the .432" bore is my Puma carbine. In my opinion proper fit is the key to shooting lead bullets without depositing lead in the barrel. Bullets sized the the same size as the cylinder throats (which will normally be larger than groove diameter) shoot great in all my revolvers, w/o leading even at magnum velocities, and for my single shot and my Puma I go for at least .001" over groove diameter, a bit more if I can (some bullets drop from my molds at just .431"). So, slug the barrel of your gun and either slug your cylinder throats or use pin gauges to find your throat diameter. Some info on how to measure your gun...
http://www.lasc.us/Brennan_2-1_Measu...Dimensions.htm