Here is my load data for the 6,5x50SR mm that simulate the original ammo specifications of the different service bullets, Spitzer and Round Nose the Japanese used.
I tested these in my Japanese Type 38 Rifle (三八式歩兵銃 / sanhachi-shiki hoheijū) No Series / Serial Number 55XXXX that was made at the Imperial Japanese Army Tokyo Arsenal (日本帝国陸軍東京砲兵工廠 / Nippon Teikoku Rikugun Tokyo Hōheikōshō) located in Koishikawa (小石川), that was a bring-back by my grandfather Captain Vernon C. Hoyt that he had acquired in Japan in 1946. Each test load was fired in two successive five-shot strings from the prone supported using a front rest at a range of 200 meters using a Beta Master Shooting Chrony® chronograph which was located 15 feet ahead of the muzzle to measure the velocity of the bullet. All test loads above were developed at the Albuquerque Shooting Range Park which is located at an elevation of 6,009 feet above sea level.
I personally found that my particular rifle does not like boat-tailed bullets, they just do not group or shoot well at all.
"All reloading data contained on this post is to be use at your own risk and any failures, mishaps resulting from this data will not be directed towards me or this group”, again these are be “USED AT YOUR OWN RISK", this should be used as a guide to help develop your own loads. I am not responsible for any accidents for using this reloading data.
6,5 x 50 SR mm Japanese Loads:
Cartridge Case: Norma or Privi Partizan Užice
Cartridge Case Length: 1.980
Primers Used: CCI Large Rifle # 200, CCI Large Rifle BR2, CCI Large Rifle # 34, Remington 9 1/2 Large Rifle, Winchester Large Rifle / Standard
Spitzer Bullet: Original bullet was.262 diameter, weighing 139 gr.(9,0g) with a flat-base
Hornady .264 140 grain ‘Interlock’ Spitzer Soft-Point / Flat-Base (BC: .490 / SD: .287)
Nosler .264 140 grain ‘Partition’ Spitzer Soft-Point / Flat-Base (BC: .498 / SD: .287)
Speer .264 140 grain ‘Hot-Core’ Spitzer Soft-Point / Flat-Base (BC: .498 / SD: .287)
Powder:
IMR 3031 / 31.5 grs. = 2500 FPS / 770 MPS
IMR 4064 / 33.0 grs. = 2500 FPS / 770 MPS
IMR 4166 / 34.0 grs. = 2500 FPS / 770 MPS
IMR 4831 / 37.3 grs. = 2350 FPS (Reduced Gunso Load)
H 4831 / 37.3 grs. = 2350 FPS (Reduced Gunso Load)
Overall Length: 2.985 to 2.990 (original length of complete cartridge is 2.995)
Note: When using this OL, the Hornady .264 140 grain ‘Interlock’ Spitzer Soft-Point / Flat-Base will not be to crimping groove on them, they will be much longer outside of the cartridge case.
Round Nose Bullet: Original bullet was.262 diameter, weighing 160 to 163 gr. (10,4 g) with a flat-base ...
The Japanese military switched from round nose bullet to the spitzer bullet in September of 1907
Hornady .264 160 gr. 'Interlock' Round Nose Soft-Point / Flat-Base (BC: .283 / SD: .328)
Norma .264 156 gr. Round Nose Soft Point / Flat-Base (BC: .283 / SD: .328)
Powder:
IMR 3031 / 30.7 grs. = 2300 FPS / 701 MPS
IMR 4064 / 32.1 grs. = 2300 FPS / 701 MPS
Overall Length: The original length of complete cartridge made by Japanese was 2.995 and the ones made by the British by Royal Laboratory and Kynoch was 2,955
I could not get to these OL with my seater die (RCBS) with the plug all the way up in it so my OL is shorter but is spot on to the Norma OL of the commercial ammo they sell for the 156 gr. Round Nose Soft Point which is 2,855
200 meters on 6/19/21, the target was a steel plate painted with a humanoid silhouette on it. I was using Speer .264 diameter 140 grain ‘Hot-Core’ Spitzer Soft-Point / Flat-Base bullet loaded with 31.5 grs. of IMR 3031