Found this over on the Cast Boolets forum
In the 38 SPL the N32C Tin Star proved to be a very good powder. I tested with the 105 and 125 gr cast bullets with 3, 3.3, 3.6, 3.9, 4, 4.2, 4.5 and 4.8 gr of TS. Psi ran from 9,200 to 14,900. Velocity of selected loads from Uberti ER with 4 3/4" barrel were; 3.6 gr at 607 fps, 3.8 gr at 672 fps and 3.9 gr at 716 fps. The 3.9 gr load was recommended for CBA shooting.
The 125 gr cast was tested with 3.8, 4.0, 4.2, 4.5, 4.8, and 5.1 gr N32C Tin Star. Psi's ran from immeasurable (not enough psi to expand the .38 SPL case and put strain on the barrel) to 18,800. The 3.8 gr load ran 688 fps and the 4 gr load ran 745 fps out of the 4 3/4" barreled revolver. Accuracy was also excellent out of the Contender test barrel up through the 5.1 gr load which was at the SAAMI +P MAP for the cartridge.
The N32C was excellent in the 44 SPL under a 205 gr cast bullet. A selected CBA load of 4.6 did not have sufficient psi to measure. Velocity was 643 fps from the 5.9" revolver SAA barrel. Accuracy was 2.6" for the 10 test shots at 25 yards. Internal ballistics were excellent with an SD of 9 fps and an ES of 28 fps. A max load of 6 gr gave 14,500 psi also with excellent internal ballistics.
In the 44 Magnum under the 205 gr cast bullet 4.5 to 6.6 gr N32C was tested. No PSI measurement was recorded as even the 6.6 gr load did not give sufficient psi to expand the magnum cases and put a measurable strain on the Contender barrel. That generally requires 8,200 - 9,000 psi. The selected TS load of 6 gr with the 205 gr bullet ran 697 fps out of the 5.9" SAA barrel.
In the 45 ACP 5 gr of N32C was found to be excellent under a 230 gr cast bullet. The psi was 13,800 and velocity out of the 5" M1911 was 752 fps. Accuracy was excellent.
Larry Gibson