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Post by bradshaw on Dec 15, 2012 21:08:49 GMT -5
FREEBORE was practiced on the Virginian Silhouette Dragoon forty years ago by Interarms' Rod Sward.
Now, an alleged alternative is offered, and they call it "taylor throating." According to the Jungle Drums, the alleged alternative is nothing other than freebore itself.
Perhaps that is why no one volunteers to supply an angle, such as a 2 or 5-degree forcing cone. Unless someone proves "taylor throating" has an angle----similar to a forcing cone----it is FREEBORE. No More, no less.
I would only want freebore reamed in a revolver barrel of mine, on a lathe, after the barrel was removed. Emphatically so, had the barrel been over-torqued in the first place to fudge bad thread timing.
If "taylor throating" is in fact freebore, call it what it is, FREEBORE.
As for a deep, low angle forcing cone on my revolver, forget it. I want the shoulder, or "wheelbase," of a bullet to engage the rifling (or freebore, if it has freebore) while the chamber exit still supports the heal. David Bradshaw
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Post by AxeHandle on Dec 15, 2012 22:28:20 GMT -5
Good discussion topic for which I am poorly equiped with technical knowledge or experience to discuss but I'll offer a memory dump to start the process. I'm more familiar with the term "freebore" used when talking about rifles. The concept if not the full intent is the same for revolvers. Jim Stroh writes about a page about it on his web site. I believe he recommends it as a cheaper alternative to line boring, using it to overcome choke and misalignment. Gary Reeder does a similar thing to revolvers with custom cylinders and custom barrels. I've read his comparing his "Maxi Throat" to "Taylor Throating" and explaining the differences..
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Post by AxeHandle on Dec 15, 2012 22:39:28 GMT -5
Don't have any good forcing cone pictures of a Reeder custom "Maxi Throat" but I do have a shot of a Ruger 44 that has been "Taylor Throated" by Jim Stroh..
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steve
.375 Atomic
Posts: 1,505
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Post by steve on Dec 15, 2012 22:39:46 GMT -5
In my experience It hasn't helped or hurt accuracy. I'm not a pro shooter or pro hunter. I do however love custom six/five guns. I've been hunting/shooting since age 8 or 9. I do have a few customs that have been "freebored and or Taylor throated" and a few that have not. I hunt mostly wild Russian hogs on the central and north coast of California. At the end of the day, they have all worked for me. Hogs don't know the difference between my box stock model 29 or one of of my customs.
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Post by bradshaw on Dec 16, 2012 12:36:52 GMT -5
AxeHandle.... I think we're about to sugar off the confusion over "what is taylor throating?" Freebore in rifle (made famous by Roy Weatherby) and freebore in a revolver are the same thing, with the eternal difference that the revolver cylinder contains chambers separate from the barrel.
FREEBORE RIFLE The purpose of freebore differs, also: in a rifle it provides a early moment of pressure relief, ostensibly to prevent pressure spikes in "overbore" capacity bottleneck rifle cartridges where the supreme objective is velocity. (I have heard Weatherby used unrifled barrels in his extreme velocity experiments. The the 120mm main gun of the Abrams tank is unrifled. Smoothbore, or 100% freebore.)
FREEBORE REVOLVER Freebore in a revolver may be used to compensate for two faults: 1) chamber-to-bore misalignment, and 2) compression ring at barrel/frame juncture, caused by over-tightening barrel.
There is one other difference between freebore in rifle and revolver. In the rifle, as stated, the objective is VELOCITY. In the revolver, the objective is ACCURACY.
1) Chamber/bore misalignment----To improve revolver accuracy in the presence of chamber/bore misalignment, freebore allows the bullet to center-up before slamming into the rifling. Bullet upset, or OBTURATION, is reduced. Freebore of 1/4" to the length of bearing surface offers the chance of improved accuracy.
2) Compression ring----For freebore to remove a compression ring, the freebore must be reamed deep enough to extend just past the barrel/frame juncture.
DIMENSION Take a typical Blackhawk .45 Colt. Measure groove diameter. Freebore should not be less than groove diameter. Otherwise, it will not eliminate a compression ring. If groove diameter measures .451" to .4515", select a .452" reamer. To safely extend freebore just past barrel/ frame juncture, ream .800" deep. I describe this as FREEBORE .452" x .800". You may be able to ream shorter, so long as it clears the front of the frame.
Freebore typically drops velocity roughly 50 fps. When freebore helps correct faults named, accuracy is improved.
Arm yourself with the best information possible before removing metal anywhere on your revolver.
Freedom Arms offered a smooth, hard steel forcing cone insert in 1986. The insert amounted to a 1/4" or 3/8" freebore. I'm responsible for that little goober. I had been a little hard on barrels in the early silhouette days, and felt a strong need to retard forcing cone erosion. Turns out that the FA is so tight and strong, the insert proved redundant.
FREEBORE and FORCING CONE Freebore may allow use of a shorter forcing cone, as the freebore smoothes bullet transition from chamber to bore. Freebore may or may not help accuracy in the presence of a deep or off-axis forcing cone. I cannot say, because, in the first place, I cannot tolerate a deep and/or cocked forcing cone.
A barrel or frame with premature thread timing----which inspires Gorilla Monsoon at the factory to crush-tighten the barrel (in order to bring the front sight to TDC)----must be addressed before freebore.
To properly time the barrel threads to the frame, the shoulder is lathe-turned to allow the barrel to hand tighten approximately 10-degrees before top dead center (TDC). Measurement of how much metal to remove to achieve this fit is based upon the thread measurement, as each thread represents one revolution, or 360-degrees.
It would be proper once in a while to pull out old factory files, and to study drawings for what worked in the old days. Might reduce the work for gunsmiths, but they seem pretty busy these days. In the mean time, a higher percentage of shooters would become better shots, as it is difficult to improve marksmanship with an inaccurate revolver. David Bradshaw
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jwp475
.375 Atomic
Posts: 1,084
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Post by jwp475 on Dec 16, 2012 14:15:12 GMT -5
You are spot on, sir!
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