Thanks everyone for your kind words, and hints as to the 364 on the stock'waco16' - You have a good solid looking U.S. Model 1898 Krag rifle.
IMO - The large stenciled '364' is an unusual way of marking a U.S. military arm.
The gray painted number may even hint at possible naval or naval reserve use?
(FWIW - The Brooklyn Naval Reserves had 'anchors' painted on their stocks in 1908).
There are a number of American Legion and VFW Posts that have #364 in their designation.
I was able to take the rifle to our 100/200yd range on Sunday and try some different handload combinations based on the components I could get:
RP 30-40 cases
PPU 150gr RN SP bullets
Vhitavouri N140 Powder
CCI 200 LR Primers
COL 3.030"
Powder charges ranged from 35.5 - 37.5 in half grain increments (based on the data in Hornadays Reloading manual) - 10 rds for each load shot from a rest
Velocity ranged from 2100 - 2315 fps
Best Group was around 3" with a load of 37.0 grains, which I'm quite OK with.
For a rifle that's 120 yrs old and a barrel that has seen (a lot) better days, I think its more than acceptable.
And using components I get fairly easily
It really is a lovely rifle to shoot
My son was shooting with me - its him shooting the rifle in the picture
It was the oldest rifle on the range!