doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Lengthened forcing cones and proof

And yet another deflection. Keep typing, your colors are showing.

So is your return policy no questions asked????
You don't need hundreds of feedback to do what is right.
I have been running a business day in day out for 21 years. NEVER screwed a customer, not once. How about you?

I will run the risk of getting back to the original question of proofs, which this thread was supposed to be about, remember?

I did some research into failure rates of shotgun barrels both here in the US and at the two British proofing houses as well as the International Proof Commission. Surprisingly enough I could find very little actual data, mostly just discussions and anecdotes. If anyone can provide these data I would be quite interested.

As there relatively few proof houses outside of Europe other than Russian and Japan, I'd think that we would see more failures from countries that produce shotguns that are not subject to proof like Brazil and the US. I can't find many, other than barrels that have been damaged or plugged. I did find these two in the US: WINCHESTER Model 1001, RECALL: Barrels may burst on firing. and SMITH & WESSON Model 916-T SHOTGUNS
RECALL: Smith & Wesson has recalled all barrels for this 12-ga. interchangeable barrel takedown model shotgun because of defect and potential hazard. Barrels may rupture when fired.

Now I've casually looked at some of those weird shotguns that only have one barrel like the Ithaca Model 37 and Winchester Model 12 and they appear to have very thin barrels, although I've never measured one. These types of lightweight repeaters have been made by the millions, all without the "benefit" of proof and seemingly nobody seems to concern themselves with barrel failure and from what I've seen they don't need to based on the billions of rounds that have been shot through them, again apparently with a very, very low failure rate. This is just anecdotal evidence and I'd like to see some data that provides failure rates, especially from the proof houses.

I'm not suggesting that thin barrels are safe! I'm not saying that modified barrels are necessarily safe! I am seeking more hard data.

Your right WW. I'm done. Sorry for the distraction.

I dunno, Miller. I pretty much agree with you that some of it is hype, especially the part about recoil reduction, but I recall some undeniable improvement in patterns by ChuckH when he experimented with some lengthened forcing cones in his .410s. Some may say, "Well yes, but after all, .410s aren't really important anyway". My take is that the same type of pattern improvent may take place in the larger gauges, but just at much less noticeable amounts. After all, the .410 is still a shotgun, and the shells are constructed basically the same, only much smaller. This smallness may just magnify what is really happening on a smaller scale with other bore sizes.

SRH

Couldn't have said it better.

maybe proof laws are a hang over from the days of twist steel barrels, when barrel making was a cottage industry of varying quality? perhaps, now that fluid steel is the barrel making material of choice, proof laws are redundant?

One more time;
The forcing cone is not the area of highest chamber pressure. Sure it is higher than further down the barrel, but the term "Chamber Pressure" sums it up. The Highest pressure is within the Chamber, not in the cone. "Unless" you cut that cone so Looong that its taper is less than the barrel's OD you have not weakened the barrel.
This is not the normal practise of cone lengthening, they are usually around 1�" long.
Admittedly the cone Chuck mentioned in his .410 was much longer. I have seen virtually no .410's which had any concern as to wall thickness in this area. Well maybe one, a little 2" .410x.22L German combo hammer gun which as I recall weighed in @ 2�lbs. Let's just say that anything at all which might improve the pattern of the little "67.49" gauge gun is worth trying. When you get to 28 gauge & upward it's not near so drastic.

Couple comments on forcing cones and proof:

I can't find the reference now, but I recall reading somewhere that the Birmingham and London Proof Houses have different views on lengthening cones and proof status. I seem to recall that Birmingham does not consider a gun with lengthened cones out of proof but London does, but I may have that reversed. I recall that the information came from a good source but cannot find it at present.

While the chamber itself is the area of highest pressure, Sherman Bell's experiments established that simply lengthening the cone (without lengthening the chamber) reduced some of the increase in pressure that results from firing a shell that's longer than the chamber in question.

"the Ithaca Model 37 and Winchester Model 12 and they appear to have very thin barrels, although I've never measured one. These types of lightweight repeaters have been made by the millions, all without the "benefit" of proof"

Ithaca advertisements stated that barrels were proved with a "double charge of powder and 1 1/2 times the normal shot load"; or (possibly) 6 1/2 Drams Black Powder with 2 1/4 oz. of shot if the standard load was 1 1/8 oz. shot and 3 1/4 Dram Eq.
Jack O�Connor wrote in Outdoor Life in 1942 that Lew Smith, President of Ithaca Gun Co. stated the Proof Loads were 17,500 psi.
The receiver end of Ithaca 37 Featherweight barrels is marked "Proof Tested"; not sure when that started



The Winchester 1897 listing in 1904 H.H. Kiffe catalog
"The barrel of this gun has been proved with 9 1/2 drams of powder, and 2 1/2 ounces of shot."
The Banc D'Epreuves Des Armes a Feu De Liege (Proof House for Firearms of Liege) First Obligatory Proof Load for 12g breech plugged tubes intended for "Double-Barreled Breech-Loading Sporting Guns" was 21 grams = 324 grains = 11.8 Drams powder and 32 grams = 1.12 oz. shot.
For comparison, British Provisional Proof (tube bored, ground, and with chamber cut and threaded for a plug) 1855-1925 for 2 1/2� and 2 5/8� 12 gauge shells for a service load of 3 1/4 Dram Eq. with 1 1/4 oz. shot was 9 3/4 dram �Tower Proof� (�R.F.G. 2�) No. 4 or 5 Black Powder with 1 1/4 oz. shot.

It has been well established that the vast majority of "rough forged tubes" used by U.S. shotgun manufacturers prior to WW1, and even until WW2 were sourced in Belgium; both damascus and (with the exception of Winchester and Remington) Decarbonized and fluid steel, and therefor received First Obligatory Proof at the Banc D'Epreuves Des Armes a Feu De Liege.
See:
https://docs.google.com/document/pub?id=17ixogftgITEblNUWtmFBv96ZvgjK6eFell8GsAWd-KI

More on U.S. makers proof here
https://docs.google.com/document/d/1F2sQuPm05IE4VWYYnCkvuXmYEzQoWd_SQgaAfUOZEFU/preview

1913 Model 28 Marlin Repeating Shotgun Grade A with Marlin Rolled Steel "fully proved with excessive loads"



Marlin Rolled Steel is very likely the same as Winchester Standard Ordnance (Bessemer Cold) "Rolled" Steel. Cold rolling "strain hardens" steel and can increase tensile strength by as much as 20%, but with a corresponding loss in ductility.