TW,
In the 1904 Ideal Shooters manual, Doc. Hudson who was probably the best all around rifle shooter in the world at that time, was working to develop a lead bullet load for the .30 U.S. Army that would be accurate at 600 yards. His development efforts eventually lead to the development of the gas check and Ideal's (now Lyman) 311284 (210 grs.) in 1906.
His work is described in the excellent 2004 Gun Digest story by Jim Foral.... The Hudson-Krag Handloads.
One of the loads that was tried in the .30 U.S. Army was 14 grs. of Laflin & Rand's "Marksman" powder under a 195 gr. cast bullet which produced 1,350 f.p.s.
I have a small quantity of this old powder and have tested it in the .30-30 along with a number of other smokeless powders in replicating the old .30-30 "Short Range" loadings circa 1895-1924. Using a 120 gr. cast bullet, here's how it compared to 4756 & Unique:
7 grs. Marksman - 1,214 f.p.s.
7 grs. 4756 - 1,316 f.p.s.
7 grs. Unique - 1,357 f.p.s.
As we can see, in that application, 4756 is 8% faster than Marksman and 3% slower than Unique.
By interpolation then, 13 grs. of 4756 should be in the same velocity ballpark as 14 grs of Marksman.
On the other side, based on data in an older Lyman cast bullet handbook,
11 grs. of Unique = 1,355 f.p.s. and based on that data, and the .30-30 Short Range info, it would take 3% more 4756, or 11.4 grs. to get to 1,355 f.p.s.
Based on the above then it would take somewhere between 11.4 grs and 13.0 grs of 4756 to reach 1,350 f.p.s. with your 200 gr. bullet. Of course different lots of powder, primers and rifles would also have an effect. Unfortunately none of the data indicates p.s.i.
As a further reference, in the .30-06, which has a larger case capacity, with a 193 gr. cast bullet, Lyman shows 12.5 grs. of 4756 at 1,353 f.p.s. / 25,200 p.s.i. and 11.5 grs. of Unique at 1,404 f.p.s./ 24,000 p.s.i.
Have fun!
w30wcf
