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

Why would you want to remove metal from the barrel at the point where the pressure is the highest?
I leave them alone and still have all my original fingers too....

"Most of the advantages of the long cone were simply dreamed up to sell reamers & cone jobs."

I have done several and felt no difference in recoil. Forcing cones have nothing to do with reducing recoil unless it reduces velocity. You can do that by loading less powder(and save money)
The highest pressure is not near the forcing cone. It is 1 to 1-1/2" from the standing breech.

"When tested the patterns only slightly improved (less than 5%)."
What does this mean? Tighter, more open, more even, anything at all?

Some time ago I bought a very light Irish 12 bore (Hunter and Sons). It seemed to kick a lot. I had Scott Carlson lengthen the cones. When I got it back, it seemed to kick a lot.The only immediate difference I noted was that my bank balance was a bit lighter.I now follow Mr. Woods advice. I habitually shoot 2 3/4" LOW PRESSURE loads in short chambers...Or, Short RST's

Well, he's gotta be totally confused by now.

Bell's tests on long shells in short chambers mostly showed some slight reduction in pressure (a few hundred psi) when cones were lengthened but chambers still short. Longer cones on modern guns are quite common, the usual rationale being "improved patterns". But as Jim asks above, what does "improved" mean?

The advice to shoot long shells in short chambers goes back to the paper hull/felt wad days. Shooters actually got tighter patterns when they did that, because with the case mouth extending slightly past the end of the chamber, the shot charge was given some protection where it would normally have first contacted the barrel walls. But modern plastic wads provide an even greater advantage when it comes to protecting the shot, so that old advice really doesn't pertain any more (unless you're shooting fiber wads).

Usually, short forcing cones aren't a problem with longer shells. That's evidenced by the fact that the Brits and Europeans have been shooting long hulls (loaded to appropriate pressures) in short-chambered guns, going way back to before WWII. Both Burrard and Thomas commented on this practice, and noted that as long as the pressure was appropriate, hull length in and of itself was not a danger. However, I have seen a few anecdotal reports of very old (all 19th century, I think) Brit guns with very short and sharply angled cones having problems with those long Brit shells--as in excessive recoil and blown ends on the hulls. Charles Fergus, for one, reported such results in an article in Shooting Sportsman. He shot the long shells in two Brit guns, one pre-1900 and the other from the 1930's, both with 2 1/2" chambers and original cones. He got the results I described in the older gun, but no problems in the newer one. Modern loads in 2 1/2" hulls, however, worked fine in the older gun. If you get the results Fergus got with his older gun, it's certainly a good idea to stop, try true 2 1/2" shells, and see whether maybe you own one of the (relatively rare, I think) vintage guns in which you ought to avoid longer hulls.

W W Greener reported on the practice (& thoroughly condemned it I might add) of some early work of breech loaders of cutting the chambers with a step at end rather than a cone. This seemed to offer no practical advantage, was impossible to exactly fit shells of all makes as lengths had some variation & left a sharp corner, hard to keep sufficiently clean, leading to the possibility of corrosion weakening.

"ALL" guns should have their bores & chambers examined prior to ever placing a shell in the chamber & the older it is the more important this is. With all due respect to Mr Fergus (I have read his account of this also) to have ever fired that first shell in which the mouth of the case would actually open into the "Bore" itself was nothing short of Utter Foolishness. That stepped or Extremely short angled cone should have been well noted & "NO" shell fired in that gun of which its fired length exceeded the chamber length.
When the British began loading fold crimp shells in the late thirties they feared the shorter overall length might lead to some of them being mistaken for 2" shells & thus placed in the wrong guns. They thus carried out "Extensive" testing of lengthening the hulls to the point they would have about the same "Loaded" length as the roll crimp hulls of the nominal 2�" variety. They found this to be a totally acceptable practise * was adopted for I believe all nominal 2�" British shells from that point on. While Mr Bell's tests gave similar results, he really had no need tom "Find out for Himself" as it had been standard practice for 60-70 years.
I seriously question whether his tests were extensive enough to truly determine a pattern & just how much of his pressure variations were simply normal variations found in testing even a single lot of shells, all loaded "Just Alike".

I'm interested in this as well as I am considering "modifying" a spare set of barrels to my Sterlingworth by both lengthening the chambers for 2 3/4" shells and then lengthening the forcing cones to reduce pressure and "improve" the pattern. Namely I want to shoot modern shells with 1 1/8 once loads. Opinions about effectiveness of results aside, I am concerned about safety.


The barrels are ID'd by Sterlingworth as their #3 weight, which was the 2nd lightest barrel configuration.

What effect would doing both procedures have on safety? What is the consensus on this? Didn't Savage always extend the the chambers to 2 3/4" when they worked on the older Philly guns?

If it matters, I don not load my own shells.

Thanks for your responses.

-Chris

I do not see how it can hurt to have a cone shaped forcing cone instead of one with
a marked step, as most older doubles have.

If "lengthening/opening" the forcing cone means changing its "shape" into a cone,
I only see advantages.

Any input otherwise shall be welcome.

JC(Always Learning)

Interesting thread.

In the case of my 1914 Ithaca Flues 20 ga., 2 different gunsmiths have verified that the chambers were at some point lengthend to 2 3/4". But one of the smiths commented that the chambers are "just barely 2 3/4" and not a fraction more". He also noted that the forcing cones were "short" and offered to lengthen them for me.

Since then, I've been fretting over shells and pressures. I can reload 2 3/4" 20 ga. shells at the lower end of the published spectrum, say under 8,500 p.s.i., but are such pressures low enough?

According to my reading, the "issue" with the 20 ga. version of the Flues is not chambers bursting, but it's lightweight frame cracking. There seems to be some debate out there as to whether the cracked frames are the result of excessive "pressure" or excessive "recoil". I, quite frankly, have not found a satisfactoty explanation of the difference between pressure and recoil, if in fact there is a difference.

I'm at the point now where I believe that I am over-thinking this whole matter of chambers, cones and pressures. I need to start enjoying this gun with my low pressure 2 3/4" reloads, instead of continuing to worry about it.

I purchased my first Parker about 3 years ago, a Trojan 12 ga. The chambers were either original 2 3/4 or someone had lengthened them. I was able to buy this Parker very reasonable due to the fact that there were some moderate pits in the forcing cones. I measured wall thickness and determined the pits (with gunsmith help) were safe to remove. I reamed/lengthened the forcing cones and polished the bores thoroughly. I never fired the gun untill work was complete. I can say that this gun shoots as well as anyone could ask for at longer ranges. It will grind targets from the 25-27 yard line, crush pheasents at 30-40 yards and I have shot barn ducks (pigeons) at great distances with it. I have patterned this gun with English 6's (my favorite) and both barrels are excellent with nice even patterns that appear to be dense. My theory (and it's only that) is a more gradual forcing cone with less violent taper doesn't necessarily help with actual pattern that can be seen on a board, but does however help with shot stringing. IE putting more pellets on target at the same time. Untill I have won the lottery so that I can afford split second camera ability, I will never be able to prove this. One subject that seems to be neglected in this forum from time to time is shot stringing, and how negative it can be. I shudder every time one of my shooting companions talks about his pet receipe for 1 oz 28ga loads! What good do all those pellets do if they're strung out 30ft+? I believe that gradual cones allow the shot to travel at more even speeds rather than compressing the column and causing the (lead) pellets to slow down faster. Cock-imammy it may be, but it's my theory.