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What is the process to lengthen the force cones of a 97?


Guest Sheriff Pack Wolf, SASS #31917

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Guest Sheriff Pack Wolf, SASS #31917

I see that this mod is sometimes done when a gunsmith does an action job on a 97.

Please describe the tools needed and what is involved.

 

Why is this done? Is it necessary?

 

Thanks

 

Pack

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Guest diablo slim shootist

It reduces felt recoil-is costs $100 and up per barrel i believe

and best left to a good gun smith with the right tools. :D

if the shooter is small in size you can down load shells and

accomplish the same results -better to make sure the gun

is cut down to fit the shooter-if this is for a larger adult shooter

it is unnecessary IMHO. Diablo

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As I understand it, back in the old days when shotshells relied on fiber wads between the powder charge and shot column, the step from chamber to bore was pretty sharp and abrupt so the wad would seal better and faster, preventing blow-by. With the advent of the plastic wad, with an expanding skirt base like a Minie ball, the sharp angle and step of the forcing cone was no longer necessary. Gun manufacturers however continue to use the older angles ... why? ... that I couldn't tell you.

 

Having it done will reduce felt recoil, and it's said it reduces shot deformation -- which may be a concern to a skeet champion but for cowboys it's hardly a concern. Is it necessary? Some shotgunners think it is, but as Diablo Slim noted proper fitment and ammunition selection can accomplish the same thing.

 

You can do it yourself after buying $100 worth of reamer, oil, and handle, or you can hire an experienced 'smith to do it and not have the high pucker factor that comes from experimenting on your guns.

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100 bucks a barrel sounds pretty steep to me. Had my '97 done & it was no where near that price. Shop around before you have it done. I read (here on the Wire, I think) that the old paper shells originally used in the '97's were just a little shorter than the current plastic ones, so the plastic shells don't open up properly when fired. Lengthening the forcing cone allows the plastic shells to open up all the way when fired, which reduces recoil. I'm sure no gunsmith so I had a pro do it.

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Here's what Chuck Hawks has to say on the matter ... http://www.chuckhawks.com/shotgun_forcing_cone_length.htm

 

Here's an explanation with a diagram ... http://www.gunnersden.com/index.htm.shotgu...cing-cones.html

 

And here's a 'smith with prices ... http://www.shotgunchokes.com/pricing.html

 

Personally, I think if a tighter pattern is the goal you'd be ahead to have choke tubes installed instead.

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The most important reason to lengthen the forcing cone is to reduce excessive chamber pressure. The vast majority of '97s have short chambers as a result of having been chambered when a "roll" crimp over a wad was the norm and shotgun ammunition was only 2 1/2 inches long. When the round is fired in a "short" chamber, the wads and shot column are excessively compressed because a modern star crimp is actually up and into the forcing cone area, creating a semi blockage. This increases chamber pressure and eventually can be hazardous to your health and the health of your shotgun. This condition can also screw up your shot pattern.

A bi-product of a correct forcing cone is reduced felt recoil. Less chamber pressure = less recoil.

Most of the '97s marked as 2 3/4 are also just a mite short also because of yesteryears roll crimp ammunition.

Most smiths have a reamer that recuts the chamber for modern 2 3/4 ammunition and extends the forcing cone in the same operation.

 

And for those who bristle at the price for the service, the reamer ain't cheap and you only get so many cuts before you have to replace it.

 

Coffinmaker

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Guest Sheriff Pack Wolf, SASS #31917

Many thanks for the information provided here. It may have served many more than me, and it is something that I thought I understood, but understand much better now.

Sounds like a good mod for an old gun if it is increasing safety. I don't hear about many 97's doing bad things, but have heard of a few, but don't know of the specifics.

 

 

Is it needed for the sxs's that are being retro fited for SASS? BSS and chas Dailey and others? Most that I have seen of those are 3" chambers to begin with.

 

Again, when I ask a question, there are lots of answers, and most strike to the heart of the problem. Thanks again,

 

 

Pack

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If you have 3" chambers on your scatterguns already, then the 2&3/4" shells will work fine with no alterations needed. You've got an extra 1/4" for the hull petals to open fully without constriction, so in essence your forcing cone is also already 1/4" longer.

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What Colorado Coffinmaker said.

 

Those that say you do not need to lengthen the chamber are forgetting that they are talking about a gun with too short of chamber. So, as folks have already said, the cartridge opening is acting as a blockage since the cartridge cannot fully open. As a result you have a 12 gauge shotgun being shot through about a 14 or 16 gauge hole.

 

What do you think that does to the pressures?

 

So getting the chamber the proper length is the most important.

 

Since the same tool is used to lengthen the the forcing cone from 1/2 or so to 1 1/2 inches, it also helps with modern shells with plastic wads. (If you are shooting black powder, the old shorter forcing cone is said to help seal the wads better.)

 

By lengthening the forcing cone you extend the pressure curve to the pressure is applied over a longer period, which gives a lower perceived recoil. Most people can feel a difference!

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