do you reload any trez?...if so...you can use 3006 brass by resizing it to 7.7 jap specs.,trim,then use pulled, bought 303brit bullets (.313) or the cheaper & plentiful 7.62x54 bullets (.311),depending on how nice & tight your bore/barrel is,might could use (.308) .30cal bullets?...just slug your barrel & see how tight she is

...or checkout out gunbroker.com,i have seen a few people selling 7.7 jap surplus for as low as 10cent a rd.,shipping not included

happy hunting!