Originally Posted by
Patrick Chadwick
Well I and others could advise you much more precisely if you would take the trouble to post a photo or two and to measure - even roughly - the length of the narrow section. The reason why will soon become apparent.
As it is, I can only switch my crystal ball to maximum sensitivity and make a couple of deductions and suggestions from the somewhat fuzzy picture.
Firstly, what you are looking at is not actually the ballistically effective barrel. It is just a tube to give the external impression of a barrel and mount the sights. The actual barrel is the narrow bit that has been puzzling you.
It seems to be some kind of "Zimmergewehr" - i.e. indoor rifle. These were basically made in 3 different styles of construction:
1) Gallery rifles for non-military indoor use, funfairs and the like. Often with a very steep buttstock for shooting in the standing position.
2) Trainers made ex-factory to be handled and aimed like a military rifle, with a smallbore insert at the rear end, where the cartridge would otherwise have been inserted. In other words, a sub-caliber construction.
3) One-time full-bore rifles, converted by chambering an rifled insert that looks like the original cartridge case, but has a very short rifled section. The tiddly little cartridge is inserted where the primer would be on a normal case. It would be a Flobert-type cartridge - just primer and projectile, no powder charge. These were popular for home-training with a full-bore rifle in the days when you could still legally pop off a few small-bore shots at a private club or in your cellar. Not today, since (at least over here in Mauserland) they are just as strongly regulated as a full-bore rifle.
So now it is clear why one needs a couple of photos, and why one need to know the length of the narrow section - the actual barrel!
Just push in a length of copper wire that has the last couple of mm sufficiently bent to snag on the end of the narrow section, without jamming. Do NOT use steel wire, as the rifling is very fine and easily damaged by something like piano wire! A wire from a scrap piece of solid-cored electrical cable is ideal. With this, you can estimate the length of the small-bore barrel section. If it is much more that about 2" then it is probably fitted as a permanent insert, maybe set up so that it can be removed by unscrewing a threaded ring.
If it is around 2" - i.e. the length of a full-bore cartridge case - then it is a rifled case and is not intended to be permanent. However, if the thing has been left in the full-bore chamber for years, it may be corroded into place and give the impression of being a permanent insert!
The small-bore cartridge used with these types of rifle was thus a tiny Flobert-style device, of which there were several options. As you write that it is a rimfire rifle and that 6mm does not fit, then I guess it is probably a 4mm Flobert. Whether it is 1) 2) or 3) of the options mentioned above, can best be shown by PHOTOS !!!
Photos please!