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Old 06-26-2016, 09:01 PM
TimDalton TimDalton is offline
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Default Barrel to cylinder gap

I have purchased a 27-2. The barrel to cylinder gap on the right side: .005 slides in easily. .006 barely starts. On the left side .009 slides in snugly. .012 barely starts. Is this a problem?
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Old 06-26-2016, 09:55 PM
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I think you need to shoot it to see if it presents a problem. It's probably within S&W's specs, but if it were mine, I would probably not like it and may send it to have it squared up and the b/c gap cut to .005.
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Old 06-27-2016, 12:31 PM
TimDalton TimDalton is offline
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Thanks for the advice Nightowl
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Old 06-27-2016, 03:06 PM
bountyhunter bountyhunter is offline
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The SW monkeys "final fit" the b/c gap with a hand file. I have seen uneven tapered cones like you have as well as crowned ones that are wider on both sides and narrower in the middle. It's because the file rocks as they use it and rounds over the end of the cone. It's a shame but they do butcher guns on a regular basis. Did the same thing to a brand new PC 627 I bought.

Last edited by bountyhunter; 06-27-2016 at 03:10 PM.
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Old 06-28-2016, 01:38 PM
Jim NNN Jim NNN is offline
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I've had several seemingly unaltered S&W revolvers measure differently at different places on the cylinder. I'm reasonably sure this happened at the factory. And these were guns from the desirable "classic" post WW2 to 1970's era.

To me, it's a "school of thought" issue rather than an actual mechanical/functional issue. My understanding is that all of the clearances you gave are within S&W specs. So my school of thought is, shoot the gun - if there are no other issues and you like the way it shoots, leave it. No need to fix something that isn't actually broken.

I can understand people wanting their nice gun to have the proper fit, but if the weapon functions as you like and is safe, please realize that a local gunsmith could potentially change the shooting characteristics of the gun in his attempt to get the cylinder gap right. Just my opinion. Best wishes.
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Old 06-28-2016, 01:50 PM
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I think I remember seeing somewhere on here that the S&W B-C gap standard is now 0.012" or less. Maybe someone else knows about that. If so, that's pretty sloppy. Yours will probably shoot ok, may lose some muzzle velocity. The gap width has a fairly significant effect on MV.

The gap can be adjusted for a tighter and more uniform clearance, but it's definitely not a D-I-Y job unless you are a gunsmith.
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Old 06-28-2016, 02:26 PM
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I wouldn't accept that condition you describe, but to correct it would require removal of the barrel, setback of the shoulder and refit of that same gap. And I wouldn't allow anyone to 'fix' it by just filing the gap wider. It originally sure should have been done better. All apprentice gunsmiths are taught how to file while maintaining the surface square with the world and flat. I don't know if S&W will warrant that or not. Feel them out.

Here is a test that I have outlined here before. While using lead bullets with no jackets; number all chambers, get the help of two other people. With extreme caution to never get a hand in line with said cylinder gap place a white sheet of paper about 12"/14" along both sides of the handgun. Number the paper right and left and to the chamber. Fire the handgun. Repeat for the remaining chambers.

Now lay the papers out and 'read' the results of side spit, ejecta, etc. from each cylinder. Lead bit will make a much larger hold in the paper than un-burnt powder particles. IF the gap is spitting much more to the wide gap side, you have to make the determination if it is enough to justify the expense of barrel and barrel/cylinder gap refitting. .......

This test will also be good to determine if the timing is correct for all chambers. ............
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Old 06-28-2016, 06:41 PM
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Quote:
Originally Posted by DWalt View Post
I think I remember seeing somewhere on here that the S&W B-C gap standard is now 0.012" or less. Maybe someone else knows about that. If so, that's pretty sloppy.
Based on what I have seen them ship (and that I measured) up to .013" is considered in spec.

BTW: here is a picture of the forcing cone on a brand new PC 627 I bought. Somebody "adjusted" b/c gap with a mill file. I think what ticks me off the most is the monkey couldn't even take the two seconds to put a piece of tape on the top strap to keep it from being chewed up by the file.

The edges of the forcing cone were so sharp that I sliced open my finger on it.
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Last edited by bountyhunter; 06-28-2016 at 06:55 PM.
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Old 06-28-2016, 07:15 PM
Big Cholla Big Cholla is online now
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Default DON'T USE TAPE!

[QUOTE=bountyhunter;

BTW: here is a picture of the forcing cone on a brand new PC 627 I bought. Somebody "adjusted" b/c gap with a mill file. I think what ticks me off the most is the monkey couldn't even take the two seconds to put a piece of tape on the top strap to keep it from being chewed up by the file. [/QUOTE]

Don't expect tape to prevent those extra file marks on the top strap. Most tapes will be cut thru to the metal in a couple of strokes of the file.

A true pistolsmith has (probably made himself) what is called "safe files". The size and cut of file needed is selected. Then the edge of the file that must not cut or mar is ground or sanded off. Then that 'safed' edge is polished to prevent rub marks. Depending on the job, the job positioning and which hand is used in filing, the right edge or the left edge or both can be 'safed' in that manner. I have mainly smooth b*****d cut files in 6" and 8" lengths for this very purpose with one or both edged ground and polished. I also use a triangular file with two of the sides safed and polished in dovetail cuts.

On a difficult job with lots of filing to be done to finish the breech, I have been known to shape a very thin strip of brass sheet around the top strap and held in place by a pinch clamp. ............

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Old 06-28-2016, 07:45 PM
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For what it's worth, I was on the horn to S&W a few months back regarding gap issues and the individual I spoke with stated that current spec is still .010" and they'll provide warranty correction on eligible revolvers over that number.
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Old 06-28-2016, 08:20 PM
ltj9296 ltj9296 is offline
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I do not know if it is a problem or not, but I would be a little concerned as well. Just to compare, my 642 is .004 on 1 side and .005 on the other. A .006 feeler gauge will not go on either side. Good luck.
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Old 06-28-2016, 10:02 PM
TimDalton TimDalton is offline
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Is it possible that the cylinder or barrel is crooked?
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Old 06-29-2016, 05:47 PM
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Quote:
Originally Posted by Big Cholla View Post
Don't expect tape to prevent those extra file marks on the top strap. Most tapes will be cut thru to the metal in a couple of strokes of the file..
Maybe, I have some tape called kapton and it's super strong. Three layers can probably handle it. Still makes you want to cry when you see somebody do that to a new gun.

"On a difficult job with lots of filing to be done to finish the breech, I have been known to shape a very thin strip of brass sheet around the top strap and held in place by a pinch clamp. ............ "

good idea

Last edited by bountyhunter; 06-29-2016 at 05:51 PM.
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Old 06-29-2016, 05:52 PM
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Quote:
Originally Posted by Hapworth View Post
For what it's worth, I was on the horn to S&W a few months back regarding gap issues and the individual I spoke with stated that current spec is still .010" and they'll provide warranty correction on eligible revolvers over that number.
Maybe, but I have read multiple posts from people who sent .012" gap guns back to have them returned "in spec" untouched.
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Old 06-29-2016, 08:09 PM
TimDalton TimDalton is offline
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I just got off of the phone with S&W. They told me their warranty didn'the start until the 80'same. My gun was made in 1973.
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Old 06-29-2016, 08:30 PM
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Go shoot it. You could shoot it of a bench and place a piece of white poster board or the like on each side of the gun about 8" or so from each side and check to see if one side blows out more than the other.

The fix isn't easy.

Remove barrel
turn down shoulder 0.0277 and cut forcing cone end .02
reinstall barrel
final cut face of forcing cone to get .004-.006 clearance
recut forcing cone

Or live with it. I doubt it will cause any real problems if the chambers alighn with the barrel and that is not function of the gap anyway.
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Old 06-29-2016, 08:41 PM
g8rb8 g8rb8 is offline
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This could be a sign of a bent yoke. Try to figure out if the cylinder sits square in the frame. Look down on the revolver with spent cartridges of all the same manufacturer and look at the gap between the rear of the cylinder (or cartridges) and the recoil shields. It should be the same on both sides. If not the cylinder is not sitting square in the frame and the yoke could be bent. It's a fixable problem.
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Old 06-29-2016, 10:46 PM
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Quote:
Originally Posted by bountyhunter View Post
Maybe, but I have read multiple posts from people who sent .012" gap guns back to have them returned "in spec" untouched.
I have read those posts, too -- this was my personal experience, and two of my revolvers well past .010" went into S&W and were corrected gratis.
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Old 06-29-2016, 10:52 PM
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Whatever you do, keep your fingers away from the path of the fire.....lol
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Old 06-30-2016, 06:22 AM
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Quote:
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Whatever you do, keep your fingers away from the path of the fire.....lol
Ditto, I was with a guy who grasp a Ruger Blackhawk, 30 carbine, by the frame and cylinder at/near the forcing cone area and pulled the trigger. I was not watching or aware that he was doing this. I sure heard about it. He was yelping and whining pretty loud and this was a farm boy who was no woosy and had callused hands. I am sure he never did that again.
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Old 06-30-2016, 09:36 AM
Flipmeister Flipmeister is offline
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I've watched the Myth Busters vid of the fake chicken meat hand reincarnation a couple times (with a 500 Smith) and how it removes the thumb quite nicely....

While not on subject, I know of a guy who lost the end of his thumb shooting a 10 Point X bow by having his thumb above the flight rail. The bow string took it right off cleanly.

We call him 'stumpy' now.....
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