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I have a 25-2 that's had a gap of .009" for years. It's plenty accurate, but the loads chronograph about 100 fps slower than a shorter-barreled .45 revolver, no doubt due to the big gap.
My cylinder gap is way too big
- Thread starter slabside2
- Start date
I would just buy some longer bullets and forget it. lol
BigBill
Absent Comrade
You can buy cylinder shims?
Benchrest1
Member
I have a no dash 686 with a gap of .009, and it is one of my better shooting revolvers.
Arquebus357
Member
Yes...TriggerShims.com
You can get a pack with 3 each, .002", .003", .004", .005" cylinder shims. These are meant to correct Cylinder Shake. It will not effect cylinder/barrel gap unless you measure C/B gap with the cylinder relaxed rather than pushed to the rear.
Tip...you will need to rig a small magnet to reach down and pull out shims in case you install the wrong size.
scruffy
Member
My experience with a B/C gap and the factory fix on a NIB Performance Center 642 last October: New 642-1 PC Cylinder Gap
Stroker468
Member
Late entry, but...
586 no dash. .010
686 no dash. .010
629-1. .008
19-3 which spent 2 weeks under water after hurricane Katrina .006
Just adding to the data base...
586 no dash. .010
686 no dash. .010
629-1. .008
19-3 which spent 2 weeks under water after hurricane Katrina .006
Just adding to the data base...
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My guess is they will set the existing barrel in a couple of turns and, if necessary, trim the ejector rod or replace it, whichever is easier and cheaper.
All S&W barrels use 36 to the inch threads of various diameters. One turn gets you .02777. Call it .0278. So it is only ever one turn which in this case would make the extension about .0158 to long so you would then trim barrel extension about .012 to .014 in this case to get the correct gap and then trim the tip of ejector rod and center pin o it functions correctly. Maybe freshen the forcing cone a bit depending on how itt checks out.
Cylinder shims will not close up the barrel to cylinder gap. They get rid of end shake by holding the cylinder tighter to the rear.
Cylinder shims will not close up the barrel to cylinder gap. They get rid of end shake by holding the cylinder tighter to the rear.
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For those of you whom have stated best to call Smith & Wesson I would have to disagree. Last week I called to complain that my rear mbus blade on my new M&P15 was crooked and to compensate I had to crank the blade all the way to the left. I was offered a return slip with a promise of a 6 to 8 week turn around due to the sights being on backorder. I simply wanted a new sight, very easy to install and no need to ship off my rifle for x amount of weeks. I then offered to send a pic to her. The customer service agent said no need, her supervisor agreed that my rifle would have to be sent in. A little later in the day I emailed customer service with a pic of the sight attached and got a reply within an hour that a new sight would be sent to me at no charge with an attached order number. I think it's more of a matter of who you speak to.
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white cloud
Member
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My 640 Pro had this issue. I sent it back and they stated that they replaced the crane and cylinder. It took about three weeks to get the revolver back but it was done right. It is now one of my favorite revolvers.
Stroker468
Member
Upon further review...I don't think i measured this correctly. These measurements are with the cylinder pushed fully rearward. From what I've read in other posts on this site, this measurement is to be taken with the cylinder "at rest". Correct?
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No - cylinder gap is measured with the cylinder held firmly to the rear, as this is where the cylinder will be when the gun is fired.
BigBill
Absent Comrade
They make shims to adjust that. I purchased them for my n frames. I trust no one touching my guns when I can fix them. I'm learning as I go. I built a 1911 so far. I remember what I did I shimmed the trigger and hammer to center them and take the side to side play out. The hammer and trigger can drag and rub on the reciever housing adding friction to the action, adding wear shims with a moly paste eliminates the extra friction and wear.
Search you tube I also have a s&w dvd.
Revolver Cylinder Shims Endshake Crane and Yoke Shims
Search you tube I also have a s&w dvd.
Revolver Cylinder Shims Endshake Crane and Yoke Shims
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Barrel cylinder gap, or the expressed distance between the cylinder face and the barrel extension, is correctly measured with the cylinder at rest, and fully forward.
If you measure with the cylinder held back, you then have the B/C gap plus the available cylinder end shake.
If you measure with the cylinder held back, you then have the B/C gap plus the available cylinder end shake.
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BC gap
OK! Trying to fathom all this advice and no one has mentioned excessive end shake and head space! How do you correct this without affecting BC gap? Shrink the cyl window, or start over with a new cylinder? ? ? ?
jcelect
OK! Trying to fathom all this advice and no one has mentioned excessive end shake and head space! How do you correct this without affecting BC gap? Shrink the cyl window, or start over with a new cylinder? ? ? ?
jcelect
jcelect,
Excessive headspace and endshake can be corrected by replacing and re-fitting a new yoke, by stretching the yoke barrel or, more commonly, by using shims to return the yoke barrel to the correct length. When this is done, the cylinder is moved back to an "in spec" condition with respect to headspace, and the b/c gap is opened the equivalent amount. So if the cylinder is moved back .004", the barrel cylinder gap will also grow wider by that amount.
If the b/c gap gets too large, or over .012" according to the current factory spec, the barrel can be set back one additional turn, or approx .028", and the b/c spec re-set by re-facing the resulting longer barrel extension, and re-cutting the forcing cone if necessary. Of course, after the barrel is set back, adjustment of the extractor rod and front locking bolt interface is also required, which can be accomplished by shortening the extractor rod collar and tweaking the center pin's OAL.
Always remember, if the headspace and b/c gap are within specifications, end shake is a "non-issue". Some end shake is not only normal but necessary, and this gauge or space is, in fact, built into the cylinder assembly to allow for proper operation (opening and closing), the proper, unrestricted rotation of the cylinder, and for the assembly to accommodate dirt and lubricants.
Carter
Excessive headspace and endshake can be corrected by replacing and re-fitting a new yoke, by stretching the yoke barrel or, more commonly, by using shims to return the yoke barrel to the correct length. When this is done, the cylinder is moved back to an "in spec" condition with respect to headspace, and the b/c gap is opened the equivalent amount. So if the cylinder is moved back .004", the barrel cylinder gap will also grow wider by that amount.
If the b/c gap gets too large, or over .012" according to the current factory spec, the barrel can be set back one additional turn, or approx .028", and the b/c spec re-set by re-facing the resulting longer barrel extension, and re-cutting the forcing cone if necessary. Of course, after the barrel is set back, adjustment of the extractor rod and front locking bolt interface is also required, which can be accomplished by shortening the extractor rod collar and tweaking the center pin's OAL.
Always remember, if the headspace and b/c gap are within specifications, end shake is a "non-issue". Some end shake is not only normal but necessary, and this gauge or space is, in fact, built into the cylinder assembly to allow for proper operation (opening and closing), the proper, unrestricted rotation of the cylinder, and for the assembly to accommodate dirt and lubricants.
Carter
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OP
slabside2
Member
I Bought a new 442-2 yesterday and checked the gap .003 and that was tight. I checked the gun out thoroughly in the Gun shop and it looked 100% glad to report. It has the lock but i'm not going to let that rent any space in my head
Stroker468
Member
.003 BC gap? That's crazy tight!
OP
slabside2
Member
Yeah that's what I thought but after having one that was so big I'd rather have it tight.
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