I see reference to forcing cones quite a few times here. What is the forcing cone in a revolver. Do automatics have them? I had a squib last week and when I pushed the bullet back toward the cylinder, it got noticeably harder to push at the very end. Thanks for the information.
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forcing cone
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Aussie44
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A forcing cone is the tapered beginning of the lands at the origin of the rifling of a gun barrel,The forcing cone allows the projectile to be gradually engaged by the rifling, thereby centering the projectile in the bore. All guns have some type of forcing cone.
Ken
Ken
m75rlg
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Wouldn't pistols (a handgun in which the next round to be fired is located in the barrell) and rifles have a "throat" instead of a "forcing cone" as in revolvers?
dfariswheel
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The forcing cone is a revolver "thing".
The forcing cone is the funnel-like mouth at the rear of a revolver barrel.
Its more important and complicated than many people think.
Its not "just a funnel", its a critical feature that's cut with precision tools and must be properly gaged with a special drop-in gage to insure its within a narrow specification.
The forcing cone is the funnel-like mouth at the rear of a revolver barrel.
Its more important and complicated than many people think.
Its not "just a funnel", its a critical feature that's cut with precision tools and must be properly gaged with a special drop-in gage to insure its within a narrow specification.
Aussie44
Member
If you are shooting lead bullets and there is lead fouling in that part of the barrel (very common), you will notice more resistance there.
Also, The bore tends to be tighter where the barrel screws into the frame. The process of torquing the barrel causes a slight constriction there. The harder the barrel is torqued on, the tighter the constriction. How far did the bullet make it into the barrel and what kind of bullet?
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Aussie44
Member
Sounds like you have a rough forcing cone or a tight area under the barrel threads,And maybe what is stated above.
Ken
Ken
Is there an optimum angle of forcing cone by each specific caliber or would it be the same for many calibers?
Barrel threads are straight threads, not tapered pipe threads. If the frame and barrel have been properly threaded, there shouldn't be any reduction in bore diameter worth worrying about at the torque levels used in barreling revolvers.
Optimum forcing cone angles depend upon bullet material (jacketed or lead) and length of the bullet. Most of us can't tell the difference between any of the commonly used forcing cone angles.
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tomcatt51
Member
In a perfect world that's true. In our world barrels tend to be a crush fit in the frame all too often with a corresponding tight area in the barrel. Ruger is the worst but you see it in S&W's too. I've had 2 new S&W's with the barrel torqued so tight you could see a jog in the rifleing at the barrel/frame face from the barrel actually being twisted.
Ahab
Member
Amen, I've seen this too!
dfariswheel
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A constricted bore in the thread area is known as "pressure dimpling" or "pressure compression".
If the barrel is torqued in too tight, the pressure causes the area to compress, leaving a tight spot in the rear of the revolver barrel.
S&W had a real problem with this when they first went from pinned barrels to torqued barrels.
The pinned barrels weren't torqued in that tight since they had a pin to prevent it unscrewing.
The new non-pinned barrels required torquing much tighter, and S&W had some trouble with over-torqued barrels with pressure compression tight spots.
If the barrel is torqued in too tight, the pressure causes the area to compress, leaving a tight spot in the rear of the revolver barrel.
S&W had a real problem with this when they first went from pinned barrels to torqued barrels.
The pinned barrels weren't torqued in that tight since they had a pin to prevent it unscrewing.
The new non-pinned barrels required torquing much tighter, and S&W had some trouble with over-torqued barrels with pressure compression tight spots.
Actually what you are saying is not quite correct. Of course they are not pipe threads, but there will still be some constriction. Back in my silhouette days, I saw a lot of Dan Wessons with constricted bores on both ends of the barrel, at the frame and at the barrel nut. A lot of people attempted to deal with this by lapping. The constriction is not a lot, but it is there. It can be felt when pushing a soft lead slug through the bore.
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aphelion:
The darn thing was so far out the barrel on a 4" Model 19 that it was flush with the end of the barrel. If it had been out any farther it would have been sticking out of the barrel of the gun, and may not have had to push it all the way back through.
The darn thing was so far out the barrel on a 4" Model 19 that it was flush with the end of the barrel. If it had been out any farther it would have been sticking out of the barrel of the gun, and may not have had to push it all the way back through.
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