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Effect of Unpolished forcing cone?

Discussion in 'Shooting Related Threads' started by ipscmaster, Oct 22, 2012.

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  1. ipscmaster

    ipscmaster Member

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    I sent my 1187 Sporting clays gun to a very reputable Choke company for porting the barrel and lengthening the forcing cone. This has been many years ago, but I just noticed that the forcing cone was not polished and is quite rough. I just wonder if this has any affect on how the chokes pattern. Anyone have any experience with this problem? Would my patterns improve if I polish it out? Thanks for any input. Bill Crane
     
  2. halfmile

    halfmile Well-Known Member

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    Polishing is eyewash. the customers like it so the smiths do it.

    If your reamer is sharp and spiral fluted (some are not) a smooth machined finish will result. At 9,000 to 12,000 PSI there will be no noticeable difference in the passage of the wad through that area.

    I have done barrels both ways and do not polish my own any more since there is no difference. I will polish them for others if it makes themfeel better.

    HM
     
  3. hmb

    hmb Well-Known Member

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    The forcing cone was left unpolished for a reason. It is believed that a rough foring cone will grab the wad when it passes by thus separating the shot from the wad and improving the pattern. HMB
     
  4. halfmile

    halfmile Well-Known Member

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    hmb, I'm sorry to say I disagree. In most trap loads the wad has to stay with the shot till at least 18 inches down the barrel in order to get up to speed.

    This dimension will vary with powder burn rates.

    It is entirely possible an unpolished cone, for the nanoseconds the wad passes by, may create an unmeasurable pressure rise.

    I will now punt the question to Neil.

    HM
     
  5. Kevin Fleming

    Kevin Fleming Active Member

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    I think what you are observing is the difference in appearance between the hard chrome of the barrel and the exposed steel where the cones were cut. Most guys polish the cone area with a flex hone or such, which gives a very smooth, but not mirror finish. If your cones are too rough for your liking, a drill, a flexhone with some light oil should smooth them right out.

    K
     
  6. Johnny

    Johnny Well-Known Member

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    ipscmaster, there has never been any data posted on this forum that demonstrates lengthened forcing cones improves performance, period. Your post just reinforces that idea.
     
  7. ipscmaster

    ipscmaster Member

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    For many years, I shot shotgun side matches at large IPSC matches. These were speed matches on steel targets and Speed and accuracy were the key factor. I was quite successful and always looking for improvements, in both shooting ability and shotgun performance. Porting barrels, lengthening forcing cones and backboring may not individually make much of a difference, but I assure you the three combined do make a difference in my ability to engage targets quicker and keep the muzzle down better to run those targets faster and more accurately. This I know from experience and looking at the time clock. It makes sense that a faster and smoother second shot on doubles will improve your score, and that, afterall is what we all strive for. Better scores. My question was not if a lengthened forcing cone is advantageous, but if polishing it would improve my gun's performance,but thank you for your input johnny.....ipscmaster
     
  8. Stl Flyn

    Stl Flyn Well-Known Member

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    Personally, if anything is not smooth in the barrel and it is possible it is slowing down the charge, because it is rough, I would polish it out. Just for peace of mind, if anything else. After-all, most of these alterations are mostly affecting the mind, rather than the actual physical results.
     
  9. Johnny

    Johnny Well-Known Member

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    ipscmaster, I never mentioned porting. If you think it helps , that fine. But backboring and longer forcing cones will not help you "run those targets faster and more accurately." Since you didn't even notice the the rough cone till " many years" after it was done, it is doubtful it had an effect to begin with, so it is unlikely polishing it will have an effect now. But it probably wouldn't hurt either.

    Stl Flyn , you say "these alterations are mostly affecting the mind", aren't you forgetting the pocketbook?
     
  10. RedScare

    RedScare Member

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    Lengthened forcing cones reduce felt recoil.

    If you want to determine any effects on pattern use a lockheart pattern gauge. This is work intensive but will be very informative on choke and barrel effects on patterns. Then get your forcing cones polished and repeat the process and tell us the effects polishing had. Note you should pattern every choke 3x and count every pellet. I have done this on my main gun for trapshooting and it is a pain in the ass but it showed the true expected patterns for all choke and barrel combinations.
     
  11. Johnny

    Johnny Well-Known Member

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    Redscare, Exactly, how does lengthened forcing cones reduce recoil?

    3 patterns won't tell you much. You will need at least 10 for an average because they vary significantly. And you should count the pellets in each shell before you pattern.
     
  12. RedScare

    RedScare Member

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    Lengthened forcing cones do not reduce recoil. They reduce "felt" recoil by increasing the amount of time required to condense the shot column before it hits the bore because of the longer cone.

    You count the pellets after they hit the pattern. It doesn't matter how many there are when using the lockheart pattern gauge. You only figure the difference in number of pellets between the regions in the gauge. Hell I think you need like 22 or more for a valid N so I guess you should do at least 22 patterns. I said 3 per barrel & choke combo because that is what I did with good results so I guess I'm lucky.
     
  13. BigM-Perazzi

    BigM-Perazzi Well-Known Member

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    I think logic would dictate it be polished.
     
  14. halfmile

    halfmile Well-Known Member

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    The maker of my reamer said it did not have to be, in the instructions. Of course I bought it a long time ago. But the Clyme reamers are spiral fluted and produce a very good finish.

    Brownell reamers are straight fluted and sometimes leave chatter marks, which would then necessitate polishing.

    HM
     
  15. GunDr

    GunDr Well-Known Member

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    Not polishing the forcing cone after cutting is unprofessional. Whether the forcing cone lengthening works or not, the jobs not finished if it is not polished.
     
  16. Brian in Oregon

    Brian in Oregon Well-Known Member

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    The smoother the forcing cone, the easier it is to clean. I have some 1187 barrels with pretty rough cones, and they are a pita to clean. Remington claims a rough forcing cone does not affect performance.

    The only chrome lined barrels Remington used on the 1187 were the early Special Purpose field guns. This was done to prevent corrosion in wet environments, particularly for waterfowling in salt marshes. It was costly and Remington dropped that feature. These barrels should not have their forcing cones lengthened.

    It is possible to lengthen the forcing cones on the Light contour barrels. This is because that area of the barrel has the same dimensions as a standard barrel. However, light contour barrels should never be backbored, as the lighter section is too thin for that.

    Slug guns should not have their forcing cones lengthened, nor should guns used with traditional wads, like paper shells. The wads used do not seal as well as the long plastic wads in a lengthened forcing cone. And a lengthened forcing cone can cause alignment issues with slugs, opening up groups.

    And HM is right, if you do it yourself get a spiral reamer. gun Dr is right that a gunsmith not polishing a forcing cone is unprofessional. It's one thing for a mass gun maker like Remington to not do it. It's quite another for someone who is supposed to be providing better quality service.

    And that's my $0.02 on the subject.
     
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