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Joined: Nov 2002
Posts: 937
Sidelock
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OP
Sidelock
Joined: Nov 2002
Posts: 937 |
Hello!
Recently on 16 gauge Low Pressure Loading Group site we have an instance where chamber cast of a 16X67 chambered drilling showed the last half CM or so of chamber to be tapered from about 0,732 to 0,711. This is in addition to standard linear taper from base of head to area where diameter is decreased to 0,732 (as shown on American dimensioned drawing of 16 gauge chambers). These drilling chambers would not fully accept American 16 gauge chamber gauge, with the chamber gauge indicating chambers about 2 1/4 inches long. I have some old German and Swedish hammer doubles from early 1900s that also will not accept American chamber gauges, in both 12 and 16 gauges. To all appearances my guns have never had the chambers reamed, certainly not to 70 mm with American chamber reamers. I shoot normal 65 and 67 mm ammo in them and have done so for decades. Is this taper at front 1/2 cm of chamber a common feature of early 1900 German and Swedish shotguns? How about Belgium, French, Itallian, etc.?
The only rational explanation I have for such chambers is that the taper at last 1/2 cm is intended to provide a tighter fit to fiber wads just as they are leaving the hull and entering the forcing cone. Sort of a dual forcing cone, first part in last 1/2 cm or so of chamber, second part in front of chamber. Unfortunately, chamber cast of that drilling chamber does not show end of forcing cone and start of bore, thanks to shortage of chamber casting material.
Can anyone here contribute more information, explanations to this?
Thanks,
Niklas
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Joined: Jan 2005
Posts: 80
Sidelock
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Sidelock
Joined: Jan 2005
Posts: 80 |
Niklas,
I read that original post & found the chamber cast very interesting. I've never seen a chamber like that & I have not answers, only more questions.
That taper at the front of the chamber was unique, but the "forcing cone" was so abrupt that it shouldn't really be called a cone - more of a step. It looked to me that the original paper shells must have been thick enough at the neck that it evened out the step.
It might be optimized for the paper shells and card/fiber wads of 1900. In the US, brass shells were common at that time & were much thinner than paper shells. I would think there might be a problem with the larger wads, needed to seal the thinner brass shells, catching on the step. I wonder if there would be a problem with our thinner modern plastic shells and plastic wads.
Certainly I'd feed better shooting the gun if that step were not there.
Regards, Rn
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Joined: Nov 2002
Posts: 937
Sidelock
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OP
Sidelock
Joined: Nov 2002
Posts: 937 |
Rn,
I took that step to be an abrupt and small step at end of chamber, NOT a forcing cone. The diameter just before that step is reported to be 0,711 and ahead of that step it is reported to be 0,709, not much of a step really not a forcing cone and 0,709 is quite large for a 16 gauge bore. Because we don't know ID of bores, we don't know if it is quite overbored or if that 0,709 tapers down to something like 0,665, making a true forcing cone.
I would have considered that taper at last 1/2 cm of chamber to be a curosity if I did not have some old hammer doubles from early 1900s that also will not accept American 12 and 16 gauge chamber gauges to the full 65 or 67 mm depth of the chambers. FYI, all of those guns shoot really nice patterns with card and fiber cushin wads.
Lars
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