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08-09-2016, 13:44 #1
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- May 2013
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- 57
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- 10
Slugging a .357 Magnum revolver barrel
Hi, I slugged my 357 magnum Taurus 4" revolver and measured with a micrometer at .353 at the muzzle and at the forcing cone end. I've been shooting Frontier 158gr cmj and 150gr lswc. both measure .358.
I've shot about 100 lead bullets with no leading. The revolver is not accurate with a lot of flyers. What can I do to get the barrel groves up to .356 or.357.
Your input would be appreciated
Pietvis
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13-11-2016, 09:06 #2
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- Sep 2009
- Age
- 53
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- 579
Re: Slugging a .357 Magnum revolver barrel
The .353 measurement. Lands or grooves?
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13-11-2016, 12:56 #3
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- Aug 2012
- Location
- Stella
- Age
- 46
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- 10,870
Re: Slugging a .357 Magnum revolver barrel
There was a similar thread some months ago about a Taurus revolver barrel which "bulged" out in the middle with tight for and aft ends. If memory serves correct there wasn't much to do about it. Maybe a good gunsmith knows a trick or two? I know a retired gunsmith who could repair a real bulged barrel. May something similar can be done?
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13-11-2016, 15:54 #4
- Join Date
- Oct 2012
- Location
- Noord van die biltong gordyn.
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- 56
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- 9,116
Re: Slugging a .357 Magnum revolver barrel
"Fire lapping", if done correctly, should increase the barrel diameter to a better size and a tapered bore. First read up on the process.
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16-11-2016, 16:46 #5
- Join Date
- Mar 2010
- Posts
- 2,269
Re: Slugging a .357 Magnum revolver barrel
353 Is impossibly small. I have slugged a lot of barrels. Most 38 Spl and 357 were dead on 357 groove. But 356 is not particularly rare and I know of at least one Python that is 356. Bore is usually 350, so 353 is a very strange measurement. The answer to "bore or groove diameter" is that you can't measure bore diameter by slugging. I'm not too familiar with Taurus, but aren't they made with old S&W machinery ? If so, could it be that the rifling is five groove ? If so you can't measure the slug with a micrometer, you have to do it with a ring gauge. The handiest ring gauge for you and I is a sizing die. If the slug will drop through a 357 die but not a 356, you know that it is somewhere between the two, and that bullet diameter should be 357, also that 358 will be OK. Count the grooves. If there are six the slug can be miked. If so something is wrong because I can't believe that any 357 barrel is 353 groove.
The answer to "can you enlarge it" is no. Four thousandths is a huge difference and way beyond what can be done with fire lapping, which is intended for smoothing bores not enlarging them. But like I said I don't believe 353. I wrote a very detailed little book about slugging which I give to anyone who wants it. If you'd like it e mail me boothroyd@polka.co.za.
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