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 Post subject: Lenghtened forcing cones
PostPosted: Sat Mar 01, 2008 8:24 am 
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Is there any advandage with lenghtened forcing cones?

Better patterns?

Less felt recoil?

I tend to think they help but would like to hear your experiences!




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 Post subject: re: Lenghtened forcing cones
PostPosted: Sat Mar 01, 2008 9:52 am 
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I think they help, but not for recoil. In my experience a gun with lengthened forcing cones will pattern better since there is less shot deformation. So I believe it is worthwhile, just not for reducing recoil.

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 Post subject: re: Lenghtened forcing cones
PostPosted: Sat Mar 01, 2008 10:55 am 
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That depends -- How long are the forcing cones on your gun now and how long do you want them to be?

From what I've read, generally forcing cones in the 1 1/2" - 2" length are the best compromise for performance. If yours are say 1/2" long now and you have them lenghtened to 1 1/2" or 2" you may notice some reduction in felt recoil and you will probably see some minor improvement in patterning with soft shot (lead and maybe bismuth) types.

Of course, to know how much improvement you will actually get isn't carved in stone. You would need to do some patterning testing before hand and some of the same after the lengthening to determine the percentage of improvement you got in your gun.

I'm sure someone on here has done this kind of pre and post pattern testing so they can chime in with their info.

Good luck.


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 Post subject: re: Lenghtened forcing cones
PostPosted: Sat Mar 01, 2008 8:19 pm 
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 Post subject: re: Lenghtened forcing cones
PostPosted: Sat Mar 01, 2008 8:30 pm 
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Quote:
I think they help, but not for recoil. In my experience a gun with lengthened forcing cones will pattern better since there is less shot deformation. So I believe it is worthwhile, just not for reducing recoil.


Actually Sammy, the single most effective alteration to a shotgun bbl to reduce recoil is to lengthen the forcing cone. With todays harder shot and excellent wads, little if any shot is deformed in the forcing cone, but a long cone does marginally improve patterns.


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 Post subject: re: Lenghtened forcing cones
PostPosted: Sat Mar 01, 2008 8:37 pm 
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I had the forcing cone done on my BT-99 and what I found was It did make a small amount of recoil reduction. Did it change the gun pattern. I don't know. It shot good before and shoots the same now.
I'm recoil sensitive so I had it done. Would I do it again. I don't think so.
Yes it did improve it in the recoil a very small amount, but not as much as a GraCoil did after it was installed.


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 Post subject: re: Lenghtened forcing cones
PostPosted: Sat Mar 01, 2008 10:12 pm 
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I have 2 sporting clays guns, one standard bore with short forcing cones. The other with overbored barrels and long forcing cones. I've patterned both guns and the standard bores patterns actually look better to me. I like the way the standard bore gun breaks targets better too. As far as scores there's not any real difference.

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 Post subject: re: Lenghtened forcing cones
PostPosted: Sat Mar 01, 2008 10:26 pm 
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My AL-2 that had 1/2" forcing cones that I lengthened to , well actually I'm not sure how much they lengthened them. But anyway, I could tell absolutely no difference in recoil before and after the work. It did pattern better though. Not a whole lot better, but enough to make a small difference.

Quote:
Actually Sammy, the single most effective alteration to a shotgun bbl to reduce recoil is to lengthen the forcing cone.


To each his own, but I think a lot of the recoil difference is all in our heads. Another possibility is that I'm wrong. It certainly wouldn't be the first time :lol: :oops:

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 Post subject: Re: re: Lenghtened forcing cones
PostPosted: Sat Mar 01, 2008 11:22 pm 
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SS wrote:
Actually Sammy, the single most effective alteration to a shotgun bbl to reduce recoil is to lengthen the forcing cone. With todays harder shot and excellent wads, little if any shot is deformed in the forcing cone, but a long cone does marginally improve patterns.


Can someone explain to me HOW lengthening a forcing cone would reduce recoil?

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 Post subject: Re: re: Lenghtened forcing cones
PostPosted: Sun Mar 02, 2008 1:24 am 
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DrMike wrote:
Can someone explain to me HOW lengthening a forcing cone would reduce recoil?

Yes, but it doesn't reduce recoil, it reduces felt recoil. This has to do with time. A shorter forcing cone squeezes the shot quickly and a longer cone does it more slowly. The longer cone stretches the initial squeezing out longer and therefore increases the time it takes for maximum recoil to be felt, thereby reducing the felt recoil. Basically it gives your shoulder more time to take the impact.

Check out this diagram from kirbythegunsmith:
Image

Also, the pressure of squeezing the shot quickly tends to deform some of the shot. That deformed shot doesn't fly straight and causes non-uniform patterns. Another way to say it is you will have "holes" in your pattern. By lengthening the forcing cone you create less deformed pellets and therefore a more uniform pattern or less "holes".

Notice that this isn't a more dense pattern, just more even pattern.

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 Post subject: re: Lenghtened forcing cones
PostPosted: Sun Mar 02, 2008 2:01 am 
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Back when I first heard of folks haveing forcing cones lengthened, circa 1968....

the logic put forth was for an improvement (smoothing, evening) of large shot patterns...It was being done by some Dixie gunsmiths for folks in Buckshot only areas...and a little later by guys that specialized in Eastern shore Goose shooting....(it was often the same folks accually)
I believe there was improved patterns in both regards......

I would think the process would spread out the hot core (smooth if you will) of any shot size considerably.

Only after Sporting clays yuppie/newbie folks glommed on to the lenghtened cones, and its becomming a bread and butter staple of the big (briley) gunsmithing outfits, did I hear of its magical ability to reduce recoil with no required reduction in velocity nor payload....I believe this revelation awaited the repeal of certain laws formulated...(undoubtably erroneously)... by Newton

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 Post subject: Re: re: Lenghtened forcing cones
PostPosted: Sun Mar 02, 2008 1:29 pm 
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Rastoff wrote:
Yes, but it doesn't reduce recoil, it reduces felt recoil. This has to do with time. A shorter forcing cone squeezes the shot quickly and a longer cone does it more slowly. The longer cone stretches the initial squeezing out longer and therefore increases the time it takes for maximum recoil to be felt, thereby reducing the felt recoil. Basically it gives your shoulder more time to take the impact.

Sorry, but neither this explanation nor the diagram from kirbythegunsmith (which says nothing about recoil) make sense to me. You are saying that the difference in time it takes to traverse a long versus a short forcing cone - a time measured in a couple of ten-thousandths of a second - can actually be felt even though it doesn't change the overall recoil of the gun. Sorry, I simply don't buy.

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 Post subject: re: Lengthened forcing cones
PostPosted: Sun Mar 02, 2008 3:05 pm 
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OK, leaving aside the comment that if I don't understand how something works, then it can't possibly work, I'll make a few observations.

Numerous customers have had me rework their forcing cone contour to my super-long configuration, and subsequently tell me that they noticed a recoil reduction. This may have been more evident especially when they finished multiple rounds of skeet or trap and noticed a lower fatigue factor from the reduced beating. Don't pull a comment that they could have less abuse by having a proper stock fitting, since that is not germaine to this discussion, since a stock fitting may make the results even better, then, in addition. The same may be true by changing to a more compliant recoil pad.

Do you have an understanding how a recoil pad reduces FELT recoil, even though the change of recoil absorption may occur in a few ten-thousandths of a second (from one pad to another)? Even if a longer time frame, what level of time is sufficient to make you notice that the difference might be felt? Half a thousandth, a milli-second, what?

I had someone with me at a test-fire session long ago, and this person was not cognizant of any part alterations that were being tested. I had 2 barrels to pattern and was using the same frame, so the fit of the stock, recoil pad, and just about everything else was similar, except that one barrel had a super-long forcing cone. The same box of shells was used for testing, and this person remarked that the one barrel without the forcing cone lengthened was hurting his shoulder more and enough to really notice.

The comments that are of little weight would be if someone remarks that they tried shooting one gun with the forcing cones standard, and another similar gun with lengthened cones. Two similar guns without any alterations between them may have different recoil feel, all by itself. What does the comparison of different guns prove? Two similar cars may get different gas mileage and have different cornering capabilities, also. That is anecdotal evidence, not scientific examination.

Forcing cones can be of many different lengths after alteration, and the term "forcing cone lengthening" is not any more generic than "backbored barrel" means a constant diameter between alterations. Mentioning terms with no specifics proves only a lack of knowledge that specifics are necessary. A high-compression engine is what? 11 to 1? 12 to 1? 15 to 1?

I do not desire to prove ineptitude, but cannot have results that I have personally witnessed and had recounted to me be made of no consequence. Plenty of other posts recount the felt difference, so are they all deluded? Mass hypnosis? How does that happen to the person in the blind test mentioned earlier? Many similar comments are made about porting of barrels, that there is no effect. I find that the effect may not be nearly as dramatic as with a magnum rifle, and not necessarily as dramatic as some may want to say to induce a shooter to make such an alteration. Porting is not really the best thing since sliced bread.

When I have shooters that had the forcing cones lengthened on one set of high-grade double barrels, and later have several more sets improved (one shooter brought several sets by a few weeks after having the first set altered, so he must have been a believer), who am I to call all of these shooters liars? They tell me more than I could possibly learn myself, and of that I am thankful and grateful. Please don't tell me to minimize their comments to me about my work. I have to believe the preponderance of comments, since they have no incentive to lie to me to make me feel good. If I denigrate what they tell me, should I downgrade any comments that you would make to me, also?

I would rather that I was accused of being a liar than my customers.

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 Post subject: re: Lenghtened forcing cones
PostPosted: Sun Mar 02, 2008 3:28 pm 
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I don't think that anyone can argue the fact that total recoil is constant. The same shell will give the same total recoil no matter what you do to the gun. That is what Newton tells us.

How that recoil is applied to your shoulder is another thing entirely.

Newtons first law tells us that a heavier gun will help us because some of the power of the recoil is taken up in overcoming the inertia of the gun itself. So, a 15lb gun will have much less felt recoil than a 8lb gun. A 5lb gun will just plain hurt.

Another factor in felt recoil is time. In the music world we call it "attack". If you use a quarter to pick your guitar you will have a more sharp sound because the note is developed quicker; it has a sharper attack. If you use your finger to pick the same note it will have a softer sound because the note is built slower; it has less attack.

Also, consider those liquid filled things in front of guard rails on the freeway. They save lives not by eliminating the effects of inertia, but by spreading it out over time. That time is very small, but it is effective.

The diagram is a great example of how the forcing cone lengthening helps to reduce felt recoil. As you can see from the red line, the recoil is built very quickly. This will result in your shoulder having to take that recoil all at once. The yellow line shoes the recoil building a little slower. This gives your shoulder time to absorb the recoil.

Is lengthening the forcing cone the cure for recoil? No. I believe its main benefit to be in making a more even pattern. That's why I'm planning on doing it to my Trap gun. The recoil is just a good side affect.

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 Post subject: re: Lenghtened forcing cones
PostPosted: Sun Mar 02, 2008 3:49 pm 
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Those are a couple of great replies.

Kirby -- How long are your super-long configurations? Can you tell us without giving away your trade secrets?

Thanks


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 Post subject: re: Lenghtened forcing cones
PostPosted: Sun Mar 02, 2008 4:15 pm 
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How much more would it cost for the factories to manufacture their guns with this improvement built in?


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 Post subject: re: Lenghtened forcing cones
PostPosted: Sun Mar 02, 2008 6:15 pm 
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Yesterday I went to a sporting clays range and shot all day. A young man went with us that has finally got his long coveted over and under. One of my well to do hunting buddies, who has too many nice toys to not share them, sold this young man a custom Angleport worked Beretta 686 for $1,200.

Until yesterday, I thought people just peed away their money on barrel work. No they don't. That Beretta had the lightest felt recoil of any fixed breech 12 gauge I've ever shot.

It had a limb saver pad, custom ported chokes marked .723 (so it sure wasn't backbored, a super long forcing cone, and holes in the side of the barrels. It was an ugly gun. Matte finished wood and matte finished barrels. But it worked the best.

I own a very similar Beretta 687 with the same tight bores, factory chokes, no porting, but with a Decellerator pad. I'd have the forcing cones lengthened on mine, and even consent to holes being drilled in the barrels, except my gun has a set of fitted full length sub gauge tubes, that might not fit if I had the master 12 gauge forcing cones lengthened. And, I don't know if it was the angleporting or the long forcing cones, but something combined to make that thing kick about like my Super X.

After yesterday, I believe guys like Kirby, who work with this stuff everyday, and are geniune experts.

Me, I'm just a lawyer who can't stay out of pawn shops and little gun shops. I'm an enthusiastic accumulator, nothing more. :wink:


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 Post subject: re: Lenghtened forcing cones
PostPosted: Sun Mar 02, 2008 6:23 pm 
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Sorry, but neither kirbythegunsmith's nor Rastoff's reply described WHY the difference in felt recoil seems to exist. We've heard that long forcing cones "squeeze" the shot more gradually, but this has nothing to do with the time in which recoil occurs. If anything, the force of the shot on a short forcing cone (and the choke) walls will move the gun forward, reducing recoil. In any event, the time spent in contact with even a very long forcing cone is many, many times shorter than the increased times produced from compliant recoil pads, and it does nothing to explain a reduction in recoil.

Are kirbythegunsmith's red and yellow curves measured pressure curves, or measured anything else, from shotgun barrels with short and long forcing cones? Or are they an artist's depiction of pressure, force, shot "squeezing" or maybe even "recoil"?

No one is calling anyone a liar. I'm simply looking for an explanation of this phenomenon that makes physical sense. I haven't heard one yet, other than "people say it recoils less," which might be all there is. I'm not saying that it isn't true; all I'm saying is that I don't understand the phenomenon. If some people feel a difference, then I'm sure they believe they do. What I'm asking is: WHY does lengthening a forcing cone seem to reduce recoil?

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 Post subject: re: Lenghtened forcing cones
PostPosted: Sun Mar 02, 2008 6:40 pm 
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I've had the forcing cones done on four shotguns. It softened the felt recoil and improved the pattern on all of them.


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 Post subject: re: Lenghtened forcing cones
PostPosted: Sun Mar 02, 2008 7:08 pm 
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I hear you DrMike and I'm trying to explain so, bear with me. Also, I'm no physics expert, this just makes sense to me. Let me try another angle:

For every action, there is an equal, but opposite reaction. In space, if you throw a 10lb ball forward you will accelerate backward with 10lbs of thrust. Throw that same ball again, but this time try to push it through a hole that is a tiny bit smaller than the ball. You will then add to the reactive momentum because the hole is applying force in the opposite direction equal to the amount of momentum of the object that has the hole.

Change the factors yet again and force the ball through a cone that starts out larger than the ball and gets smaller than the ball. The resulting momentum will ultimately be the same, but will take time to develop. Thereby, reacting on the resisting force, your hand, at a slower acceleration rate.

Maybe that's not clear...let me try something else. What if we had a gun that had no barrel? How much recoil would you feel? I believe that you would feel very little recoil. As the energy of the shell left the chamber, the force would spread out so quickly that there would be little force in any one direction, thereby having little reactive force backward.

Remember, we have a 170lb person behind a 1 1/8oz load of shot.

Now, we add a forcing cone and barrel. This concentrates the force in one direction, forward. The result is the equal force backward. Make that forcing cone really small in diameter, and you have a lot of force going backward. The energy has no where else to go. If you lengthen the cone then the reactive force takes longer to build up and therefore, translates to less felt recoil.

Did that make any sense? I'm not a writer either and I hope I'm getting my point across.

If you had a shotgun with a steel butt plate and it only weighed 5lbs, lengthening the forcing cone probably wouldn't make a whole lot of difference. If you add a good recoil pad, good fit, hold the gun tight etc., then lengthening the forcing cone will help in the overall equation.

As I said before, I don't believe lengthening the forcing cone is the king pin in the recoil equation, but it helps. I hope this is better than before. I'm no physics expert, but this makes sense to me. If I'm off in my thinking, I hope someone will straighten me out.



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