Chrome Barrel Work And Cones

Dear Bruce,

Thanks for your worthwhile advice in the past. My question today is;

I have an Ithaca/SKB model 500 o/u mfg in Dunville Ontario. I believe Chromed bores. I love this outfit beyond words, and have been shooting skeet using the current full/mod barrel config. with remarkably good results. Sure smokes the birds!!!!

Rather than investing in a new outfit, I am wondering if it is possible to have the chokes cut to skeet or I/C, and the forcing cones done without ruining the barrels.

Thanks for the advice in advance, and keep up the good work. I enjoy your site immensely.


Dear Don,

Chrome bores? No problemo. The chrome coating does make the first cut somewhat harder, but the gunsmith will just use a specially hardened tool. If he says, “Gee, this job requires a carbide reamer and I don’t have one.” then skip him and go on to someone who does this for a living. All the “majors” will do the work for you- Briley, Seminole, Rhino, Ballistics, etc.

Be careful when lengthening the cones. How long are your cones now? Did you measure them? It doesn’t cost a manufacturer one cent more to make the barrels at the start with long cones compared to short cones. Why do you think that so many pick short cones? There’s a reason. The shorter the cone, the quicker the transition from chamber to bore. This ensures a better gas seal if there is a possible problem with the wad due to wad design or cold weather. Long cones provide a smoother transition from chamber to bore and thus might possibly damage less shot, but at the expense of possible gas blowby under certain conditions. Stan Baker has done a great deal of research on long cones and feels that cones over 2″ simply don’t add any advantage. He also mentions that the 2″ cones really only help with larger hunting-size pellets. The effect on target pellets is minimal because their small size helps them flow better to begin with.

With modern plastic wads, it probably doesn’t hurt to have cones of 1-1/2″ to 2″, but you can go overboard. I once sold a Superposed to a friend who had the cones run out to 5″. When I shot the gun later that winter, I got off-sounding shells. It never did that before. Also, if someone says that lengthening cones reduces recoil by a noticeable amount, but suspicious of gas blow-by and reduced velocity.

I’m not totally against lengthening cones, but I’m suspicious. For example, people are always lengthening the cones on Berettas and most of them already come with 1-1/2″ long cones. That’s plenty long enough. They are wasting their money. Don’t just “lengthen” cones out of reflex. Know what you have, what you want and why you want it. If your cones are lengthened and the job isn’t done right, you’ve got a real mess- literally. That chrome is gone in the throat area and you will lead up and scrape plastic like you can’t believe if the coning job isn’t done carefully.

I have one FN Superposed that I had the cones run out on. I also have several absolutely identical FNs with factory short cones. I can’t tell the slightest difference in recoil. I’m sure that long cones do change the width of the pressure curve very slightly, but I’m just not sensitive enough to pick it up.

It’s usually very difficult to discern what longer cones do to the pattern because cones are almost never the only work that is done to the barrel. Usually there is also backboring, porting or screw chokes involved in the work done at the same time. This makes it harder to figure out what does what. It might make a lot more sense for you to get your chokes cut first and then do some pattern tests. If your patterns are good, stop there. If they aren’t what you want, then consider working on the back end of the gun.

Remember, these aftermarket barrel borers make their money by putting metal shavings on the floor. The more stuff they that they can cut out of your barrels, the more they can charge you. I’m not saying that it’s all useless. It isn’t in some cases. It’s just that “more” isn’t always better and sometimes it’s worse. It’s interesting to note that Miroku (Browning Japan) has gone to overbore and porting, but has refused to lengthen cones. It makes you wonder why.

Gun makers are like any other mass merchandiser. They sell what the public thinks it wants. If the average guy thinks that porting his barrels will actually do something other than make noise, then the makers will supply ported barrels until the craze passes. We are seeing that now as many shooters are starting to avoid ported guns. Beretta is still laughing at Browning for that one.

The bottom line to all of this is:

1) Yes, you can get someone to do work on chrome barrels if they have the right hardened tools, and

2) be a bit careful of the work you ask for.

Best regards,

Bruce Buck
The Technoid writing for Shotgun Report, LLC
(Often in error. Never in doubt.)

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1 Response to Chrome Barrel Work And Cones

  1. Bill says:

    As usual Technoid is spot on and his conclusions are in concert with what Oberfel & Thompson concluded back in the 50’s in their seminal work, “Mysteries of Shotgun Patterns”. If I remember correctly, O&T concluded that a 1 1/2 inch length chamber forcing cone was optimal and anything longer was of no benefit and could actually be detrimental just like Sir Technoid indicates. Although some discount what O&T did because they did their work before many of the high speed photo capability and other more precise laboratory equipment were available; their results seem to me to still stand up to scrutiny.


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