doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Forcing cones in old doubles

Ninepointer--

I own several Ithaca Flues doubles, I have shot all of them with moderate pressure loads, and no damage as of yet, now I don't feed them with a steady diet of "boomers" either.

You are perhaps digging a little deep but that's part of the fun! I commend your willingness to keep the gun sound and SAFE. I am nothing more than a casual clay shooter and don't own a dedicated target gun anymore. I don't feed my guns more than 200-300 rounds a year (each) and I believe that as long as you don't continually stuff 1 1/8 oz loads down that beauty she'll be fine...

The idea of lead shot from a 2&3/4" shell squeezing its way through the forcing cone of a gun with 2&1/2" chambers strikes me the same as that same shot leaping from a 2&3/4" shell and squeezing through a forcing cone another 1/4" away. The later seemly more omnious if steel shot is included but is apparently not of concern to gun makers? A more gentle taper on a forcing cone, if it doesn't devalue the gun or create too thin a wall or cost too much, maybe allows for less shot deformation or damage to the shot cup and therefore is a good thing. I hope it doesn't matter because I don't want to do it. Anyway since smokless powders take up so much less space than black powder did, I don't understand why shotgun shells keep getting longer?

ninepointer-Not to hijack the thread, but the way frame cracking was explained to me was that all sxs gun barrels have a forceful downward bend upon firing. Some call this "flip" and you can see it in point of impact problems with loads in some guns. The longer and lighter the barrels, the bigger the bend. The long barrels are a lever working against the angle of the frame. The frame will crack at the angle and frequently flow towards the hammer axles and then to the sear axles. The heavier the shot charge, and the faster the load, the more pronounced this becomes. Just keep everything moderate and you'll probably be fine. I know a guy with a 20 flues and he uses it with no problems.

Pressure vs Recoil;
While the statement often made that recoil is caused by pressure "Is True", it is also "Equally True" that pressure is not a factor in determing recoil. Factors in recoil are the amount of weight being moved & the speed with which it is moved.
You can for instance with proper powders load a 3" 20ga with 1�oz shot & push it out the muzzle at some 1250 fps with pressures no higher than another load using a very fast powder pushing 7/8oz to some 1175fps. This equals 3/8oz more shot @ 75 more fps.
Now you have only to fire both of these loads from a gun of about 6lbs wt to see which has the most recoil, though both have essentially the same pressure.
Now which of these loads will stress the frame the most?? My vote goes for that load producing the heaviest recoil, but I know of no way to prove it except to place a gage which will measure the stress applied across the juncture of the standing breech to the bar. I do not have the equipment to do this. Most of this "Flexing" back of the standing breech is produced by the back thrust of the shell against the breech, not by the flip of the bbl.

Miller, the problem with the above is that we, right here, often lead folks astray on the above practice. Someone has a short-chambered gun; what's the response? "Well, if you want to be safe and don't reload, just shoot 2 1/2" shells in it." Only problem there is, some shells marked 2 1/2" are longer than that. Right on the box of Kent Gamebore Pure Gold shells I have, it tells me that shells with a "65/67MM case length" are suitable in "Guns with a chamber length of 2 1/2" or longer." So, mine's got 2 1/2" chambers . . . they ought to be safe regardless of what's beyond the chamber, because the shells are British, my gun's British, and it fits the description. (Maybe we should always add a caveat when we tell them all 2 1/2" shells are fine.) But they're not--as demonstrated by what happened to Fergus--if their fired length happens to exceed 2 1/2" (which it might). I suppose Gamebore's "out" there is the rest of the sentence, which reads: "Nitro proofed to a service pressure of 3 tons per square inch (850kg per square cm)." Those proofmarks, of course, are only found on guns made (or reproofed) since 1954--which would eliminate the pre-1900 guns, unless they've passed modern reproof.

After all this discussion, I measured all 4 of my doubles and an old Iver Johnson single shot 12 gauge.

I have the forcing cone reamer and the gage to check before and after.

Here is what I found. The Fox Sterlingwortth, 1931 vintage, Ithaca double, 1936 Vintage ,Iver Johnson, (At least as old) and an older pre 1900 Raick Freres Belgium double all have the identical chamber length to the forcing cone for a 2 /1/2" shell. Another Fox double,which I rebarrled with Brownell's barrels sometime in the late 80's also has the same length.
What I don't know and cannot measure is the angle of the forcing cone or it's length.Gues I will leave them all alone.

Larry;
If a neophyte to old guns made that mistake I would tottally agree with you, he was just following oft repaeted advise which is in most cases too general & broad in its scope, with no included caveats.
I can really speak only for my self but I will tell you if I ever make the mistake Fergus did it "WILL" be from Utter Foolishness/Carelesnesss.
I truly do feel that if You did it it would be the same & that When Fergus did it was the same.
Surely he examined the bore to be sure there wasn't a Ditrt Dauber's nest or other obstruction there. A chamber end having a step or extremely steep angle is "Extremely Easy" to see visually. It should certainly have been throughly checked out & the length of the shells to be fired determined prior to ever being fired in this very old & irreplacable gun. I don't recall now exactly what gun it was, but seem to recall it was from perhaps the 1860's or no later than the 1870's.
It is very rare to encounter a chamber of this type & they will be mostly found in these Very old guns. I don't know it for a fact but I seriously doubt a modern proof house would proof such a gun without the cones being re-cut
When working with these very old guns one needs to mostly ignore all thoise general statements & treat each on an individual basis. The main fault I find with Bell's articles is that im my opinion he was just too casual & cavalier about the subject, giving virtually a blanket recomendation with no exceptions cited.
This just really Ain't the case as shown by Fergus' experience.

Miller, I found the Fergus artice: "Short Chambers & Steep Cones", Shooting Sportsman, May/June 99. (Further information on the gun in question in "Iron & Steel Intertwined" in the same issue.) The gun in question was a Westley Richards made in 1894; passed reproof under the 1954 rules of proof. He had the gun looked over by Alfred Gallifent, who apparently did not comment on the cones and what they might mean as far as choice of ammunition goes.

Larry;
Thanks for the info. I was pretty sure the article I had read on it was in Shooting Sportsman , but was thinking an earlier gun. The fact it had passed post 54 proof does lend some credence to the idea he thought he was OK.
I do know though that "I" would know better than to shoot a shell in such a gun having a fired length which allowed the shell end to actually lap into the gun's bore. Thus if I had done this I would still consider it an act of Foolishness, every one else will just have to decide for themselves as to how it applies to them.
I am doubly surprised that WR would have cut such a chamber at that late a date, & that the proof house would have passed it as they would have obviously been well aware the common British shell would exceed the actual chamber length.

Some surprise there for me too, Miller, not having reread those articles in some time: like you, that the proofhouse would pass it (particularly the modern reproof) and that Gallifent--I never met him, but I know he had a good reputation as a doublegun smith--would not have said something to Fergus.