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Forcing cones and plastic wads


elgreco
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Hi can someone explain to me how a forcing cone has any effect on the lead shot if it is held in the cup of a plastic wad? I can understand how the cone would have an effect on a felt wad load as obviously the shot is in direct contact with the barrel all the way up but finding it hard to get my head around how it can work with a plastic wad.

Cheers

Tom

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Hi can someone explain to me how a forcing cone has any effect on the lead shot if it is held in the cup of a plastic wad? I can understand how the cone would have an effect on a felt wad load as obviously the shot is in direct contact with the barrel all the way up but finding it hard to get my head around how it can work with a plastic wad.

Cheers

Tom

 

Forcing cones aren't meant to impart any affect on the lead shot, their purpose is to ease the passage of the shot cup from chamber into the main bore via of course the small area of the cone. Some argue extending this area makes the step less peaky and so eases this transitional passage which reduces recoil (which is provably incorrect) and in doing so reduces potential damage to the pellets which should lead to better patterns. This second point isn't easy to measure as you need to do before and after tests of patterns to establish superiority one way or the other.

 

So in essence whatever affect the forcing cone has on the plastic shot cup is then somewhat imparted onto the pellets. Plastic wads can be quite unfussy with cone lengths as they're able to expand to fit, this is not always the case with felt/fibre wads which can perform poorly with over size cones.

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The pellets in the wad have gone from 0 to 600 miles pr hour in a few milliseconds the forward chamber is over 20 mm the wad will expand to this with the shot which will momentarily shorten it's length. When the wad reaches the forcing cone the wad size is reduced from chamber size to barrel size (now about 18.4 mm )thus momentarily lengthening the shot colum again this is where some pellets are squashed by each other

 

Hope this helps

 

Deershooter

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Hi deershooter, thanks for the explanation. I didn't really think about the forces expanding the load width but surely if the shot is held in the plastic cup it would be better to have a smaller cone diameter to stop the load expanding to fit but would still be protected by the cup?

Cheers

Tom

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Hi deershooter, thanks for the explanation. I didn't really think about the forces expanding the load width but surely if the shot is held in the plastic cup it would be better to have a smaller cone diameter to stop the load expanding to fit but would still be protected by the cup?

Cheers

Tom

 

You can have a smaller cone diameter, just drop down a gauge say from 12 to 20 but why would that be better ? Or achieve different (shot lengths within cup) by using less or more shot such as 24/28/21g - makes no odds other than the fact the fewer are fired the fewer pellets will arrive at destination.

 

Whatever the theoretical for and against arguments are for cone measurements the reality is that the Americans have done before and after tests on the same barrel with no perceptible superiority either way and done side by side tests between different barrels, again no percetible difference. Basically just down to minute shot to shot variations and individual interpretations and slants.

 

Real life blind firing have also disproved any recoil claims although Newton already beat them to that one.

Edited by Hamster
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Thanks Hamster, so basically the forcing cone is just an elaborate sales gimmick.

Cheers

Tom

 

Well no, its basically a reducer to get shot/wad down to barrel diameter. If you didnt have one and just went straight from the cartridge at say 20mm down to the choke at 18mm say then things might not work so well!

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Thanks Hamster, so basically the forcing cone is just an elaborate sales gimmick.

Cheers

Tom

 

Obviously we need a cone area in front of the chamber not least to allow the opening up of the cartridge crimp but various manufacturers have their own versions and tolerances and many aftermarket people have made some fairly implausible claims almost non of which stands up to practical scrutiny. Put it this way, it's not as clear cut as enlarging your forcing cones and getting measurably better patterns. Nothing makes a difference as easily and as reliably as experimenting with different chokes which are of course located at the very end of the barrels. :)

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