Jim Watson
Member
And Tokyo Arsenal is not a member, so any new 6.5 Arisaka is reverse engineered from 70 year old enemy gear.
What most people call "headspace" has another factor, sometimes called case support. A case must be supported in some way against the firing pin blow and against being pushed too far into the chamber. Support by the case shoulder is not really a very good way of doing that; it was adopted only because a rim interferes with feeding in a repeating or auto weapon. Contrary to being precise, it is very imprecise, with a lot of places to go wrong in rifle chambering and cartridge manuacture.
In some cases, the shoulder is not at all good, being either too small or at too shallow an angle to be effective. There are plenty of examples; H&H developed the belt not to strengthen the cartridge base, but because the small and shallow shoulder of the .375 rimless was simply too small. The same is true with cartridges like the .35 Whelan and even the .35 Remington, which can have misfires if the chamber and the ammo are not quite perfect.
A semi-rim, like a belt, is a compromise between the good support of a rim and the smooth feeding of a rimless (cannelured) case
Slamfire
Very interesting analysis.
Very interesting analysis. I have had misfires in the 35 Whelen and I believe it was due to the slight shoulder. I sized my cases to maximum cartridge headspace. When I close the bolt, there is no movement as the case is an exact fit to the chamber. I don't like doing this as I normally want a bit of clearance.