I've got a fair idea of various philosophies and practices of fitting a cast bullet to an individual chamber's peculiarities. SAMMI chambers, short throats, long freebores, tapered throats, all sorts of stuff. I've even read a bit on dual-diameter paper patch bullets and while I haven't shot any, I get the gist of it and find the idea compelling. 

I don't think I've read anything about fitting bullets to early European chamber throats that I'd be inclined to refer to as funnel-like or conical. These are chambers with no distinct step between the neck and the throat, just a conical section running from full outside neck diameter to bore diameter. I've always thought of this as a 19th century thing and mostly military, but I might be wrong in that assumption. I've also always assumed it was a design based more on ease of reamer grinding and maintenance than any particular design intention for the chamber. I plead near total ignorance of the actual particulars and have concluded that just from looking at chamber casts.

Has anyone had any success or even thoughts on a general approach to loading for these chambers? Is this just a case of bore diameter paper patch bullets long enough to reach past this tapered area are advisable and the rest is an opportunity for placing bets?

I've never really had a good answer to these sorts of chambers. A friend has enlisted my help in seeing how well he can get his 11.7 Danish Rolling Block to shoot and I'd love to have more of a starting point with this chamber than I do currently.

Custom molds and dies and whatever else are doable, but I don't even have much in the way of ideas that feel like a solid start. I'd really like to set my friend up with something better than some hollow-base 405s.

oneatatime wrote on Mar 17^th, 2019 at 7:37pm:


     Agree.   I load a lot of old, odd calibers and have the best results using the largest bullet that can be seated in a fired case.    The 41 Swiss caliber likes a bullet with a belt around it the same diameter as the OD of the fired case neck and the base of the bullet the diameter of the ID of the case.    The old Swiss 7.5 mm "GP90" ctg used a .307 bullet pp'd up to about .320, and has a throat of that diameter for about 1/2" ahead of the chamber.   You NEED a bullet that will fill up that space.   A schuetzen rifle in that caliber had a throat that was .328, and groove diameter of .299(sic).  Loaded with .328 bullets, the first 10-shot group out of it was right at 1.1". Those bullets are squeezing down almost 1/32" of an inch.   
      Many military rifles will not chamber groove diameter bullets, and they are therefore difficult to load with s......less powder.    Sometimes one can do some machine work on the necks if they are thick enough.  I have had luck in some calibers with bore-riding noses and a stack of wads to fill up the rest of the neck, behind as big a base as you can accommodate.   With repeating rifles, you will run into ctg length problems using this approach.

CHRIS
RGChristensen

I have a CPA Schuetzen Jr. with a conical 6 degree throat from the outside of the case mouth.   It works very well with the correct bullet breech seated.  I have no idea about fixed ammunition though.   The bullet I use is, strangely enough, a Buffalo Arms Creedmoor bullet that was tapered specifically for breech seating.

I also used to own a Browning BPCR with a chamber much like that, except it was 12.5 degrees.  It shot fixed ammunition quite well. 

Chris.