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Old March 9, 2009, 09:46 AM   #1
whiplash
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forcing cone and cyl gap ?s

I did a search, but I just didnt get what I was looking for. Anway, I wanted to ask for some opinions/guidance on forcing cones and cylinder gaps on my revolver. I have a Taurus M44 (44 mag). Ya, I know its no high dollar gun, but it is mine and I like it. It shoots ok. My forcing cone is well....pretty rough to say the least. And I could have done a better job at the finish on it (if I had the tools etc.). So, is reworking the forcing cone something that I can do, or is that better left to the gunsmith? If so, whats the going rate? And whats the opinions on what degree to cut? Ive seen 5 and 11 degrees. I also looked at the cylinder gap, and it was .011. I dont think this is a big thing. I thought I read where the SAAMI max gap was .012. One last question...The throat dia in all six was .429. Is this too tight? I mainly use hardcast .430 (w/ gas check) and hardcast .431, sometimes jacketed .430. I cant measure the groove dia due to the last two inches are compensator. I am hoping someone can give me some opinions/guidance/education on these topics. Any past magazine articles? I did manage to find and Handloader issue from '02, but was looking for me. Any info would be greatly appreciated.
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Old March 9, 2009, 02:48 PM   #2
brickeyee
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Quote:
So, is reworking the forcing cone something that I can do, or is that better left to the gunsmith?
Look at the tooling from Brownells.
Forcing cone cutters are available.

Use VERY carefully.

It is VERY hard to put metal back.
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Old March 9, 2009, 04:57 PM   #3
whiplash
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Very true! I will have to try to take a pic of this throat, its narley awfull...
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Old March 11, 2009, 11:36 PM   #4
MountainBear
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Send it to a gunsmith. He needs to check to "headspace" on the forcing cone. If its bad, he may need to set the barrel back in order to reset the forcing cone. To optimize the angle it may take a different angle. You do not want a compound angle on your forcing cone. These are things a gunsmith will know and can do this properly.
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Old March 12, 2009, 04:32 PM   #5
brickeyee
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Quote:
He needs to check to "headspace" on the forcing cone.
Headspace does not involve the forcing cone.

The flat area on the barrel against the cylinder sets the gap, not the throat.

If the barrel cylinder gap is to large it can result in loss of velocity and excessive flames.

If a throat is rough it can be cut or polished to a smoother finish without altering barrel cylinder gap or headspace.
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Old March 12, 2009, 10:40 PM   #6
MountainBear
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Thats why "headspace" is in quotations. The forcing cone needs to be set at a certain depth depending on the angle used. There are special gauges, much like headspace gauges that check the forcing cone depth.
The gap is always contentious. Target shooters like them tight because you lose less velocity from escaping gases with a tighter gap. However, if the gap is too tight, your gun can jam up. I believe the standard from Khunhausen is to set the gap between .003" and .005".
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Old March 14, 2009, 01:17 PM   #7
brickeyee
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There are special gauges, much like headspace gauges that check the forcing cone depth.
Forcing cone depth does not control barrel cylinder gap.
Feeler gauges are used to assess barrel cylinder gap.

Revolver barrels have a flat area on the end of the barrel.
That controls the barrel cylinder gap.
The forcing cones largest diameter is always smaller then the OD of the barrel at the cylinder.
A thin edge here would quickly be eaten away.
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Old March 14, 2009, 07:52 PM   #8
MountainBear
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I'm going to stop responding here. I know what I'm doing, but either you people can't understand me, or I can't convey what I am meaning.

I don't know about you guys, but I actually am a gunsmith.

No worries, I guess I'm just not a teacher...
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