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Joined: Dec 2001
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Some years ago while attending the NSSA World Skeet Shoot in Savannah, GA, I had an interesting conversation with a Winchester Factory rep. We were discussing the Model 50 automatic, and the fact that it was never chambered for the 3" shell. He related to me that he had at one time worked for Simmons, and that they did convert the M50 for 3" shells. They did so by cutting a chamber with a sharp shoulder at 2 3/4" and no forcing cone. When fired, the first 1/4" of the shell would cut off cleanly and thus allow ejection. These were paper shells, and they had to stop this modification with the advent of plastic hulls, since they wouldn't cut off cleanly. I wonder what kind of pressures were created in those chambers?

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It's interesting to see how opinions of this have changed in the last five years when there was about a 50/50 split on the advisability if lengthening cones.

I did a test about five years ago at the Southern Side by Side and a couple of other shoots. I had a Fox A grade with cut 26" barrels. I had one forcing cone lengthened and left the other as it was. I allowed those interesting in participating to shoot four shots two from each barrel and found no statistical evidence at all that there was a change in recoil.

On the card the shooters filled out, I did ask if they thought lengthened cones reduced recoil and those who were of that opinior almost always noted much more recoil on one barrel or another.

I didn't let them peek but several tried.

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Originally Posted By: DaveWE
When tested the patterns only slightly improved (less than 5%). Dave, this is going to sound a little rough, but, please, understand it is not intended to be personal to you. It is intended to be generic for comments about pattern "improvement."

1. What is your definition for "improvement" of a pattern (5% of what)?
2. How many patterns were tested for each variable (10 is a real good number for valid statistics)?
3. Which analysis method was used?

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Originally Posted By: ninepointer
Interesting thread.

According to my reading, the "issue" with the 20 ga. version of the Flues is not chambers bursting, but it's lightweight frame cracking. Agree. There seems to be some debate out there as to whether the cracked frames are the result of excessive "pressure" or excessive "recoil". It is from pressure. The backthrust of the shells is due to pressure and is contained by the standing breech. The force on the standing breech is carried to the action bar around the angle between bar and standing breech. The greater the radius of the corner, the less the stress riser effect. When a force canges direction, it tends to "pile up" as sharpe corners. Note that high pressure guns, (think double rifles) have a good radius and a reinforcement lump of metal to help resist the "pile up" of force on the corner. I, quite frankly, have not found a satisfactoty explanation of the difference between pressure and recoil, if in fact there is a difference. Pressure is the result of the propellant producing gas faster than the gas can flow away from the "fire." The pressure is equal in all directions. Recoil is due to conservation of momentum and is the result of the weight of the ejecta traveling down the barrel. The action feels recoil on the rear where it mates to the stock.

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. Good plan. However, understanding is a good idea also. If you are still unclear as to recoil and pressure, post back.

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Originally Posted By: Steve I.
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. Sorry, but patterns are never "even." 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. Don't think so. Shot flows within the barrel. When it encounters the forcing cone, it, following the venturi principle, accelerates at the expense of a pressure reduction. So, the shot flows nicely from the shell mouth, through the constriction of the forcing cone, and into the barrel in a very orderly fashion. There is no reason to expect this to reduce total recoil, "improve" patterns, or shorten shot strings. 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. Do the math on target movement during shot string passage. Hint: it isn't a whole lot. I shudder every time one of my shooting companions talks about his pet receipe for 1 oz 28ga loads! How does heavy pay load create long shot string? What good do all those pellets do if they're strung out 30ft+? Where did you find the number of 30 ft? 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. Actually, the pellets will flow as a unified group, accelerating according to the pressure on the wad base and accelerating to maintain mass flow rate through the constrictions of the forcing cone and the choke cone. Cock-imammy it may be, but it's my theory. "Cock-imammy?" Naw, but this is where horse sense doesn't fit to science. Post back if something I said doesn't ring true for you.

Last edited by Rocketman; 01/12/11 11:44 PM.
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Don, re heavy payload and shot string . . . one theory of string holds that the longer the shot column--all else being equal--the greater the potential for increased string. The example always used is the 3" .410, with its long, skinny shot column, but the 3" 20ga is often mentioned too. But heavier payload is always going to make the shot column longer.

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Dick Jones' post is interesting in stating that five years ago, fifty percent thought fooling with forcing cones was bad, fifty percent thought it was good. Well in over fifty years of buying and shooting shotguns of all types, my opinion has never changed. When I multiply the number of guns that I have owned in fifty years by the average cost of shipping a gun to a barrel butcher and paying his bill, I have saved about a third of the value of the house I am living in by not even once having a barrel butchered. Of course, this is assuming none of those guns would have increased in value because of the butchering. I am pretty safe in that assumption.

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I've said it before and I'll say it again: About 40 years ago, when the truth was more important than pimping for the advertisers, the Q & A section of the American Rifleman contained the following question: "does lengthening the forcing cones and/or back-boring reduce recoil?" This was back when all this barrel magic crap was just coming on the scene. The answer given was: "nothing you can do to the inside of a shotgun barrel will reduce recoil unless it also reduces velocity". This was true then and it's true now. The only difference is that magazines now, including the Rifleman, are little more than parrots, accepting anything in the manufacturers' release letters as gospel, no matter how outrageous the claims. The reason gun makers now offer much longer cones and over-bored barrels is that so many in the buyers' market believe this nonsense. The facts haven't changed but when lies are repeated often enough, people start to believe them.


> Jim Legg <

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The shot column is longer in fractions of an inch and the shot string is claimed to be longer in multiple feet. Why?

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Jim, you are on safe ground if total recoil is accepted as the right metric. I, personally, will hold in reserve the question of sensing peak payload acceleration as recoil. This question has neither een proven nor disproven, IMO.

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