Forcing cones

[DAk28]

I have a Remington 870 supermag I shoot LB 3 inch #5 it is throwing a great pattern with the Carlson LB choke 660. My question is should I get the forcing cone lengthened, or let it be since has a great pattern already. What will I gain by doing this

[SumToy]

You have a 50% chance on pattern.  It will help recoil and uniform the pattern but not always pick up numbers. 

[sixbird]

I had the forcing cone lengthened and polished on my Benelli and the patterns actually got substantially worse. I was able to recover them but it took all new ammo and a number of new chokes before i could get back where I started. I had about ten years worth of ammo that now shoots marginally with the new setup. So it cost me some choke tubes and quite a bit of ammo that I had bought at pre panic prices...I wouldn't risk it...

[Snoodsniper]

I had the forcing cone lengthened in both of my BPS barrels. I'd have to agree with Sumtoy. I'd also say that I've had positive results and will do it again. My latest project gun will have the forcing cone done when the time comes.

[BandedSpur]

If you're getting good patterns, I'd leave it alone. No guarantees it will help, and it might hurt.

[taylorjones20]

I've had it done on quite a few guns.  I like the results... 

[DAk28]

Thanks for the info I think I will let it alone , just always looking for the edge I guess. Also Sumtoy I appreciate your honesty about it your in the business to make money from it and didn't try to sway someone into doing something to make a buck.

[PALongspur]

I've had it done on two guns and I'd do it again.

[sixbird]

I think if I was doing  a new project gun, I would consider it. If I had one that was already shooting well, like Dak said, I'd leave it alone. I think that's a wise decision. All you need is a gun that'll kill turkeys reliably out to 40-45 yds. After that, it's "overkill" so to speak...

[longislandloco]

Gosh, 50 years ago none of us knew spit about forcing cones, polishing barrels, how did we do it.

Give me the old days, all we had to worry about was hiding the new gun, LOL.

[Gooserbat]

I had it done ony 870 and it helped with lead and hurt hevi.  In fact with magblends if I can get 140 its good. 

[allaboutshooting]

It has been my experience that the results from having a forcing cone lengthened depend in large part on how well it's done. Allowing a shot charge a longer transition time helps to stabilize it. In the old days, we only thought of lead shot and longer forcing cones were thought to help that type of shot keep from being deformed (on the front side) upon entering the smaller bore too quickly. Cushioning wads were supposed to keep the shot (on the back side) from being deformed upon set-back.

Shell makers offered harder lead shot, high in antimony, to help keep it round and resist the forces exerted upon it on both ends of the shot charge. That along with better wads helped to some extent.

When tungsten-based shot came along, it was supposed that since the shot was so hard, a longer forcing cone was no longer important. Most shell makers concentrated on keeping the shot away from the bore with thick wads and recommending very open chokes. As time went by and everyone learned more about the performance of tungsten-based shot, wads got thinner and chokes got tighter but hardly anyone thought about the effect of stabilizing shot charges and the effects of harmonics on shotgun barrels.

When you have some time and it will take some time, you might want to read this article http://allaboutshooting.com/blogs/blog/98758599-harmonics-in-shotgun-barrels

The major effect of lengthening a forcing cone on tungsten-based shot is that it allows a longer transition period, a longer time for the shot charge to stabilize, before entering the bore. If however that transition is still too abrupt or poorly done, it will not benefit the shot charge.

Shotgun barrels can be precise instruments for delivering a shot charge or they can be "scatter guns", all depending upon how much care is taken in the "internal geometry" of them.

Thanks,
Clark

3/1/2016 Corrected Link Information

[maytom]

Here is a picture I saved that shows the details of having your forcing cone done.

[Izzyjoe]

Wow, you guys know you're stuff, I'm really blow away at all knowledgeable folk on this site, and proud to be a member here! Before I joined here I didn't know a whole lot about shot gunning, other than point and shoot! I can honestly say that I'm a whole lot smarter than before. Thanks to all.

[reynolds243]

Had it done to my sbe2 and it shoots fantastic


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