Japanese Ammuntion and Rifle Testing

[jmoore]

I've shot my 97 sniper and I found that scope w/o adjustments is terrible to use because you need to try to focus on the same sight picture each time and that sight picture might be where there are no cross lines/hairs, (+) use as a cross reference to the same point each time. I wonder what lines a matching they zeroed a matching scope to? Ray

The scope CAN be zeroed, but it's a giant pain in the rear unless you have an actual fixed vise at the firing point. After shooting a group you clamp the rifle in the vise and adjust the entire unit so the the reticle is directed at your aiming point. Lock everything down. Then remove the teeny grub screws that fix the objective lens in place and use the special spanner to turn the lens 'round and 'round until the reticle now points at the group center. It's wierd and hard to cipher how the eccentric inside won't repeat in one turn, but it doesn't. The bother is you will have to do it over for ammo and weather changes, so it's only exact (maybe!) on the day of the zeroing. (Hopefully tightening the grub screws back won't throw it off too badly, also!) Mine's off zero a bit agin, which makes testing a bit more challenging.

As a complete novice, what were the O rings for? Smaller case in a larger bore?

Smaller case in a bigger chamber. The Arisaka chambers run on the largish side for reliability, and the cases often swell unevenly at the first firing. The o-ring trick was developed to negate headspace issues with rimmed cartridges (it pushes the case hard against the bolt face), but I hoped it would work to also center the cartridge in the chamber for it's first firing. More uniform primer ignition and some theoretical accuracy gain due to better bullet to bore alignment were intended.

[seabot2]

Very good test. I also have to agree with you in that I have yet to find a consistantly accurate T38 rifle. I had many pass through my hands and didn't find one with exceptional accuracy. I tried a side by side comparison with a Swedish M96 using the same bullet weight of 140gr, and loaded with powder for similar velocity, around 2400ft/sec. The T38s would group OK for the first three or four rounds (2" ) then start having flyers (4"). The Swede M96 would stay consistantly in one group (within 2") regardless of how many shots were fired.
I found that if you clean the T38's barrel after every three or four rounds, you could keep a consistant group. Seems that the metford rifling or the barrel's steel may be at fault in residue build-up. Cleaning patches would come out black with residue. The Swede's cleaning patches did not come out as dirty.