Lengthened/Stretched Forcing Cone?

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Lengthened/Stretched Forcing Cone?

Postby Small Block » Tue Sep 11, 2012 8:03 pm

Most shotguns come to the end user with the basic degree of taper at the forcing cone. Some, with reserch, feel there is an added benifit to having this done after you purchase the gun. Personally i've had this macining done to both my 3" Charles Daly auto loader and my 3.5" Charles Daly auto loader. I feel i'm getting better patterns at the kill zone with more pellets getting there at the same time rather than a longer shot string. I've killed birds at some pretty impressive ranges with the big gun. Anyone else have this done to their gun?
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Re: Lengthened/Stretched Forcing Cone?

Postby T Man » Wed Sep 12, 2012 8:42 am

Do you "feel" you are getting better patterns, or do you actually have data?
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Re: Lengthened/Stretched Forcing Cone?

Postby apexhunter » Wed Sep 12, 2012 11:39 am

As has been posted a few times before, there is a tremendous amount of data from testing lenghtened forcing cones with steel shot and most all of the results show very little to no change in patterns. Lead load tests provide different and more favorable results as the softer shot is more prone to deformation with a shallow taper.

this is not to say that your barrel and your load will not react favorably to the change but in testing the difference with steel shot patterns before and after lenghtening the forcing cone is virtually non existant.
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Re: Lengthened/Stretched Forcing Cone?

Postby 3200 man » Wed Sep 12, 2012 1:58 pm

So , if longer forceing cones are no advantage with less abrupt taper , why do barrels with no forceing cone shoot better ?
Some say tighter patterns and less recoil with shorter shot-strings ?
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Re: Lengthened/Stretched Forcing Cone?

Postby apexhunter » Wed Sep 12, 2012 2:34 pm

Most all barrels these days have forcing cones as the diameter of the chamber (and just ahead of the chamber) is larger than that of the bore. The forcing cone is simply the taper from this diameter down to that of the bore. Lengthening the forcing cone is simply a matter of reducing the angle of the taper to a more gradual one...you can think of it as a funnel ahead of a pipe and all you are doing is using a longer funnel with less of an angle to the pipe but whatever you pour into the funnel has to travel down the pipe. Regardless of the taper angle the fact is that the shot charge will be reduced down to the bore diameter and with steel it seems to not matter how quickly or gradually this occurs; at least that is what all of the testing has shown.

Many do get better patterns with lead shot after lengthening the forcing cone as the shot is less prone to deformation and therefore holds a better pattern. But very few if any see differences when shooting steel shot. Tests have been done for several years and the results of thousands of patterns done before and after the cones are lengthened show virtually no change with steel shot.

As far as shot strings go, this is a matter of the bore diameter compared to the total mass of shot that has to travel through the bore diameter and has very little to do with the forcing cone. Basically there is nothing wrong with lengthening the forcing cone but do not expect dramatically different patterns with steel shot. For clays or bird hunting with lead one can expect some change (good or bad depending upon the barrel and the load) but the change with steel shot is virtually non existant. Browning uses an oversize bore and Mossy basically has a 10 bore barrel on a 12 gauge gun...both are intended to reduce the constriction or cramming of the shot charge as it goes towards the muzzle. To get markedly improved patterns the entire bore would have to be enlarged (hence the backbored or overbored barrels from the likes of Mossy and Browning) to make more room for the shot charge as it travels to the muzzle.
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Re: Lengthened/Stretched Forcing Cone?

Postby 3200 man » Wed Sep 12, 2012 4:41 pm

I also understand the reasoning for oversize barrels and it is a great help for shooting steelshot ,especially large shot (1's or
bigger). So my thoughts are ,if you are shooting a skinny bored barrel ( .724 ) it can only help with steelshot ? If you are shoot-
ing a payload greater than 1 1/8 oz the shot string has to be increased along with P S I . With a 12 bore barrel being designed
for a 1 oz payload and trying to push more steelshot through it , doesn't make sence with short forceing cones ?

Educate me ?
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Re: Lengthened/Stretched Forcing Cone?

Postby Small Block » Wed Sep 12, 2012 7:18 pm

T Man. You read it right. "I feel" and the only data i can produce is what is in the skillet at the end of the day.....or maybe i just got better with my shooting after 50 yrs. Pick one that suits ya. Data is all over the internet along with lots of opinions includng mine. The question is still, " anyone had this done to their gun"
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Re: Lengthened/Stretched Forcing Cone?

Postby 3200 man » Thu Sep 13, 2012 7:49 am

Yes , 2 Mod 12's
2 870 3" Wingmasters
1 3200
1 MX 12 34"

And , they shoot lead and steel really good , to !
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Re: Lengthened/Stretched Forcing Cone?

Postby T Man » Thu Sep 13, 2012 1:59 pm

Small Block wrote:T Man. You read it right. "I feel" and the only data i can produce is what is in the skillet at the end of the day.....or maybe i just got better with my shooting after 50 yrs. Pick one that suits ya. Data is all over the internet along with lots of opinions includng mine. The question is still, " anyone had this done to their gun"
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I dont need or want a statistical analysis of the shot velocity through yardages and the average deformation of pellets before and after etc. Have you gone out and patterned your gun both before and after to see what change to your pattern has happened?
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Re: Lengthened/Stretched Forcing Cone?

Postby 3200 man » Fri Sep 14, 2012 2:52 pm

OK , just a few from my experience .
Less recoil
a couple percentage points better patterns ( lead and Steel )
shorter shot strings
longer life with my hulls
less ware to my guns actions ( Auto's )
Less set-back in the wads , No steelshot sticking in the wad
So , Why Not have longer forceing Cones ?
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Re: Lengthened/Stretched Forcing Cone?

Postby chase870 » Mon Oct 29, 2012 10:06 pm

2 870 supermags I carry a matching pair I did it to reduce the recoil and it does (for me) no way to prove it but I am happy with the reduction in recoil I had them ported as well. I fell it improves the pattern actually patterns well on paper and kills ducks and geese dead. I will do it to every gun I shoot large shot in
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Re: Lengthened/Stretched Forcing Cone?

Postby 3200 man » Mon Oct 29, 2012 10:33 pm

I also believe with faster payloads of steelshot a reduction in taper of the forceing cone allows less radial preasure to
the barrel , looking at indents of the shot in wads , makes me believe this ? What do you think ? Overbored barrels with
longer forceing cones makes sence to me ? Why wouldn't it ?
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Re: Lengthened/Stretched Forcing Cone?

Postby apexhunter » Tue Oct 30, 2012 1:34 pm

If one "feels" that it gives bettter patterns and less recoil then by all means go for it. As for shot strings, reduced recoil and the like there is absolutely no test results to show this.

In simple terms the shot charge will be constricted down to the bore of the barrel before exiting through the choke tube, period. A charge of a fast loading of steel is in the barrel for less than .002 seconds so the taper angle or length of the forcing cone is relatively insignificant with steel shot in terms of how long it takes to be reduced to the bore as it does not conform to another. Shot strings are a function of the mass of the shot and the total mass of the entire charge in relation to the bore diameter so forcing cone length has no affect there as well.

As for recoil reduction, the laws of physics come into play and the only way to reduce recoil with the acceleration and final velocity of the shot charge being constant is to add weight to the gun. People (including me) sometimes talk about "perceived recoil" but this is subjective and cannot be measured...therefore it is a moot point. Different guns may have different "felt" or perceived recoil but this is a matter of gun weight and ergonomics and how that gun directs the recoil into the shoulder.
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Re: Lengthened/Stretched Forcing Cone?

Postby 3200 man » Thu Nov 01, 2012 6:23 am

With a barrel overbored by .018 and 1 1/2" FC , shooting 492 grs of steelshot through it , my field testing tells me it's
better than my barrels with skinny bores . To each their own , I guess ?
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Re: Lengthened/Stretched Forcing Cone?

Postby Uncle Buck » Wed Nov 07, 2012 5:33 pm

Small Block wrote:T Man. You read it right. "I feel" and the only data i can produce is what is in the skillet at the end of the day.....or maybe i just got better with my shooting after 50 yrs. Pick one that suits ya. Data is all over the internet along with lots of opinions includng mine. The question is still, " anyone had this done to their gun"
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Yes- a SBE I and a Nova. Pattern board shows improvement w/ 1's and 2's. Not so much w/ BB's. The improvement w/ Hevi-Shot 2's is minimal but measurable.

Recoil 'feels' reduced as well especially in the Nova.
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