doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Pros and Cons of extending forcing cones

I am in the process of geting the chambers polished and the smith recommended extending the forcing cones.

What would be the Pros and Cons to extending the forcing cones?

Pro: Gunsmith gets more paid work.

Con: You have less money after he does work.

Really, I NEVER have the forcing cones lenghtened on my old guns. I will polish them if rough (common situation for cheaper guns) -- that really does make difference in evenness of patterns. I do have one that previous owner lengthened forcing cones. Does not shoot any more even patterns than those with short cones from early 1900s.

Niklas

I agree 100% with Niklas.
I have the forcing cones lengthened on my target guns.

Shooter's myth that it would decrease recoil and improve patterns. No proof for any claim.

This is just good old fashioned snake oil.
Modern powders are progressive burinig powders and the wad type, wad pressure , crimp depth and forcing cones all play a part in developing the fire in a very progressive way.

Lengthen your forcing cones and the first thing you will notice is much dirtier barrells as you are now not getting a full burn and if you put your favourite rounds over the Chrony you will find that they are not going as fast. Recoil is generally reduced by the drop in velocity

Next thing you do is get a faster burning powder and guess what your speed is back up but so is recoil.

If pattern quality is a problem buy better shells or shoot lower velocity shells, if recoil is a problem shoot better quality low velocity shells.

There is nothing really new in shotgunning, it was all sorted out in the 1800's and that remains true to today, but there are plenty of snake oil salesmen out there who will tell you different in an effort to part you and your money.

Hotrack

I personally, conducted my own tests on the same gun, lengthening one barrel's cone and leaving the other. The first test was standard forcing cone vs. a 1 1/2" long cone. I felt no recoil difference, but did see a decernable difference in pattern around the edges. The "flyers" were less and the pattern bprder more defined. Some might say it had the effect of making the pattern smaller. I say it reduced the damaged shot that created the edge irregularity. Either way, it wasn't my imagination. Next, I cut the standard cone to a 4" long cone and compared it to the 1 1/2" cone. I could see little difference. There might have been some slight improvement in pattern edge quality, but it was inconclusive to me, since I didn't do quantitative analysis nor a statistical sample of shots fired.

Me? I could not tell any recoil drop from a longer cone. I think many modern clays guns have longer cones than a early gun or SAAMI spec chamber and won't benefit. My K80 had longer cones than a SAAMI chamber. I do believe it matters in pattern quality from my testing. If the guys above have tested more thoroughly than I and have a different opinion, so be it. Until I see something to convince me otherwise, I believe it helps the pattern.

If the walls of a gun are thin, easing the forcing cones will take off a little strain according to my barrel man. He also recommends the job if cones are very steep, as this will reduce pressure and recoil will be eased a little. I recently had this done to a client's damascus barreled Purdey that was down to 17 thou towards the end of one tube.

If cones are very steep, you may find anything other than 65mm shells (in a 2 1/2" chamber)get ragged at the ends because they are not opening flat -this produces extra pressure and more recoil and requires surgery unless you stick to the 65mm shells. I had this as an issue with a Purdey re-barrelled in the early 1970s and solved the problem.

If any of the above are a concern, it can be a good idea.

However, doing it for its own sake is not somthing I routinely have done. 'If it ain't broke don't fix it' generally works a guiding principle for me.

Agree with Small Bore. Bell's tests report some reduction in pressure when cones are lengthened. But like SB, I doubt I'd bother unless the cones are short and steeply angled--which they sometimes are, on older guns.

Brister reported a reduction in felt recoil (with no velocity loss) on a gun that had both steep cones and was underbored, after barrel "surgery". However, he not only had the cones done but also had it overbored, so it's hard to tell what caused the change.

Like Dig and Larry, I don't routinely modify my barrels with a long cone even though I own two reamers and all the hones. In fact, I haven't lengthened a forcing cone in more than ten years and that was on some Citori's and the BSS test gun. Virtually all of my vintage guns have been left alone. I just don't see the big, big improvement in either doing it or not. If I were a serious clay competitor, I'd probably insist my gun have long forcing cones, overbore, and long cone chokes. But, I'm not.

PS, I take that back, I did lengthen a barrels cones on that 410 nitro special Lefever a few years back, because the chambers had been lengthened poorly. I had to have my friend custom grind a taper pin reamer to match the chamber diameter. The end result was that the chambers ended up at 3" long and long cones. And yes, I do indeed routinely shoot 3" 410's in that gun.

How long are the cones on a Becker Fox?

Mark