Lengthening forcing cones

[pigeon48]

I was considering lengthening the forcing cone of a 3 inch chambered 12 gauge Mossburg M-930 shotgun and was wondering if anyone that has done their chamber this way got any beneficial results from it?...and if so, were the patterns any better?..or the same?...also can any gunsmith do this job and how much would you expect to pay for the modification?

 

[oneounceload]

If you only shoot 2-3/4" ammo, you already basically have a somewhat lengthened forcing cone

Choke determines patterns, but lengthened cones are said to help reduce in pellet deformation, so it might help a little on flyers in the pattern, it does seem to help (a little) in reducing recoil

Most smiths have a minimum bench charge; in my area that would be about $50. Mike Orlen in Maine comes highly recommended for his barrel work (see shotgunworld.com)

 

[Virginian]

When i did a lot of barrel work some years ago, the lengthened forcing cones did give some pattern improvements in the 3% to 5% range. And, although we couldn't quantifiably measure it, my buddy and i could identify the modified barrel 95% of the time with heavy loads. All tests were with heavy loads. The recoil just felt a hair milder.

 

[cfullgraf]

I lengthened the forcing cones on my 2-3/4" chambered skeet over/under in the early 90s. I feel it reduced the felt recoil.

But, lighter shot loads, 1 oz or 7/8 oz loads, have more effect in reducing felt recoil.

 

[Dave McCracken]

Before and after having a good smith lengthen the cone on an 870 barrel, I patterned it with my 00 of choice.

IIRC, about 4" less spread at 25 yards. Of course, YMMV.

 

[natman]

If you only shoot 2-3/4" ammo, you already basically have a somewhat lengthened forcing cone

Not really. What he has is a long chamber with a standard forcing cone. Lengthening the forcing cone makes the tapered section longer with a more mild angle.

 

[PapaG]

I've done a dozen or so with a reamer we made up years ago. We "think" it helps patterns, and we "think" it helps recoil but have no quantifiable data to support it.

It stands to reason that if the transition from shell to bore is more gradual (longer tapered section) that the shot will be less deformed and the abrupt change made more gradual. I guess that is what we tell ourselves. I'll continue to do it to my trap and skeet guns and not worry about whether it really helps or not...I think it does.

 

[oneounceload]

Not really. What he has is a long chamber with a standard forcing cone. Lengthening the forcing cone makes the tapered section longer with a more mild angle.

Exactly - it is not the same, and it tries in some odd fashion to function like it - to a very mild point anyway. It also depends, like choke taper, how thew forcing cone is designed