doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Lengthening forcing cones....good or bad?

Mike, can you point to the specific source of your Gough Thomas reference? I have 3 of his books and I can't remember reading anything about the forcing cone issue--but it could well be I've just forgotten it.

Sure!

May take me a little while.

Best,

Mike

I have my own reamers, hones, etc., for several gauges to lengthen cones. I've tested enough to satisfy myself that patterns get better with a longer cone. This seems to be more dramatic in the little .410. I attribute the pattern improvement to less damaged shot from abrupt changes in the shot path. Since more percentage of the shot load is in contact with the barrel wall with a .410, I think it reflects in the more dramatic improvement. I use a reamer that produces a 3" long cone in a .410. I've tested my barrels enough that I'm satisfied.

I would not do it on a pristine "collectable", but do believe it helps patterns (less fliers) and reduces recoil. Further, if you are starting with a strong gun like a M21, you can shoot an occaisional 3" shell with no problem. When I buy a gun to "upgrade" it is SOP .... chokes, FC's, wood, engraving, refinish, etc.

After more than 100 years of choke bored guns with standard forcing cones that shoot just wonderful patterns, why would we drill out our forcing cones because someone says that it will improve patterns? Does it make patterns tighter? Does it make them more even? Does it add to the center thickness? Maybe Chuck can clarify that. Drilling out forcing cones costs money and takes metal out of the high pressure area of your gun. Why would anyone drill the cones out of a double barrel shotgun unless he were making a living shooting that gun for serious money? My experience is that the "gun rapers" don't shoot very well and are looking for a crutch.

Or someone is stuck in "time warp" and unwilling to consider tech improvements that most progessive manufactures now offer as "Standard" spec for newest guns. I really don't want anyone to "rape" your K32.

Please tell us who you believe are progressive manufacturers.

Considering the thousands of dollars I spent, and the potential damage I did, plying my body with nicotine and alcohol in my youth...I think spending a couple hundred dollars for barrel modifications is clean, harmless fun.

Mike the Ripper

SHOTGUNS AND CARTRIDGES, third edition, page 136

The question then arises, why not a really long cone- five or six inches maybe - by which the pellets would be gently eased back in to the bore? Such cones have been strongly advocated, notably by that doyen of American shotgunners, Elmer Keith. They would certainly lower ballistics (Journee lost 33ft/sec of muzzle velocity by lengthening cones from about 3/8 inche to 1-1/4 inch), but might well achieve a net gain with high-pressure cartridges by the improvemnt of patterns. Superior patterns are worth than marginal values of muzzle velocity.

Years ago, it was the practice of many of our best gunmakers to bore their guns with what could fairly be regarded as a prolonged extension of a normal cone. This was a tapered entrance -- perhaps 9 or 12 inches long - from the cone to the bore proper. In a high-class specimen which I have measured, the bore diameter immediately in from of the cone is .738 inch tapering down to .730 inch at 10 inches form the breech.
But long cones rely absolutely for any merit they possess on the high quality of the wadding. If the wad does not expand adequately immediately on its emergence from the case, a long cone will invite gas to escape past it, and if any considerable amount does so, bad patterns, accompanied by serious balling, are almost inevitable. Here, two of the virtues of the modern full plastic wad stand out conspicuously; the skirt wad provides an efficient gas-seal, and any gas that does escape is prevented by the shot-cup from invading the pellets.

I remember some other remarks by him on this subject - more to the point about balling and written before plastic wads became commonplace

Best,

Mike

I've had forcing cones lengthened on several guns. The only difference ever noted on paper or on the shoulder was my 3 1/2" 10, which had factory cones cut short and slightly off-center. On the pattern board, two ounce bismuth handloads gained percentage points at 60 yards with improved eveness, possibly from fewer broken pellets. No scientific tests but it did seem to make the heavy recoil more of a push than a slap. If the loads lost velocity it didn't matter with the large pellets (BB).