Yep, that link tells me I am "FORBIDDEN". (Oh, the horror of it all!)
The Type 97 sniper rifle is 6.5mm, based on the Type 38 rifle but having a longer, turned down, bolt handle and a monopod. The mount is screwed to the left side of the receiver and also has dowel pins. It has a dovetail onto which the scope top base slides and a locking device that can be released with a spring-loaded button. The scope is 2.5 power.
The Type 99 sniper rifle is much the same, but based on the Type 99 rifle. It has a larger and heavier mount to accommodate a 4-power scope. Some Type 99 top mounts were altered to use 2.5 scopes, apparently to use stocks of those that were on hand. The receivers were marked 99 type; the Type 99 sniper was apparently never given a separate adoption date.
All mounts and scopes were fitted to the rifles. Fitting a sniper base to a standard rifle would probably not be too difficult, and the bolt might be altered. The scopes came with a leather case, carrying straps and lens cleaning brush.
I have no idea what "single action hammer" means in JD0x0's quote.
In spite of tons of WWII reports of Japanese "snipers" (which was considered a dirty word and typical of the sneaky Japanese - no upright, honest, god-fearing, clean-cut American boy would shoot from ambush!!) few true sniper rifles were brought back. Apparently most, if not all, of those sneaky snipers used the plain infantry rifle.
Jim