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Old January 21, 2002, 05:08 PM   #26
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Great Post! Thanks Jim!

I learned alot from this post.

1. I need a better set of feeler guages, mine only read down to .006.

2. Why my Ruger SRH .454's cylinder gets so darn tight. I had been seriously contemplating sending it back to Ruger and have drove my gunsmith batty trying to discover the ailment. I bet he knew but it was such a simple thing he overlooked explaining it to me.

The Cylinder gap on the SRH is very very small my .006 guage looks like a 2x4 when I tried to measure the gap in lockup. I have been shooting .45LC reloads in the gun, which I suspect causes even more crud to build up in the cylinder gap area. Next range trip I'll be usuing .454 reloads and make sure to clean the front of my cylinder every 36-48 rounds and see what happens.

Thanks Again, this makes me wanna go Revolver Shopping!
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Old January 21, 2002, 05:54 PM   #27
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So what's the maximum acceptable cylinder gap?
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Old January 23, 2002, 09:38 AM   #28
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"With the trigger still back all the way, check for cylinder wiggle. Front/back is particularly undesirable"

The beater S&W snubbyI just picked up has a slight bit of front/back movement. How does a person quantitate this? How much is too much, and is it mostly an accuracy issue, or a safety issue?
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Old January 24, 2002, 06:18 AM   #29
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Azrael256: "too much" is usually listed as over .007, typically the maximum factory spec (most factories, anyhow).

As the gap gets bigger, you're "losing power" - energy is spraying out the sides rather than through the barrel behind the bullet.

Too small and "crud buildup" rapidly causes the cylinder to bind. At .001" you could mebbe get a whole cylinder off with it still spinning free - and maybe not. It would depend on how clean-burning the particular powder is.


First thing, clean it real good. Next, shoot it, and see how long it takes to start binding with the ammo you're using. Dirty ammo might clog up a .002" gapped gun too fast for your tastes. My .002" snubbie .38 starts binding at around 40 - 50 rounds, which is fine by me.

If you've then established that you really want more gap, take a very fine polishing stone usually used for knife sharpening, so long as it has a flat that'll fit inside the open frame, and gently polish the back of the barrel down by .001" or so. Go real slow, take gentle strokes, it'll be fine and you'll get EXACTLY the gap you want, and no bigger.

Send it back to Ruger and God only knows what you'll get back . .007" would still be "in spec" but you do NOT want that.

Atticus: front-back movement is a sign of wear. In some cases, it's frame stretching, which I'd worry about in an early-model alloy .38 (too much +P could easily stretch the frame). If not that, it's wear on the cylinder or the metal (front and rear) that the cylinder "spins against", which actually isn't so bad. In both cases, it's probably made the cylinder gap "grow" some.

If everything else at least lines up right, a gunsmith might be able to shim the cylinder at one end (usually the front) and make it tight again, while also checking the barrel/cylinder gap.

Assuming no frame cracks, it's not a safety issue, unless it's so bad that the cylinder bores are no longer pointing "straight down the barrel" and/or the cylinder gap has grown to enormous proportions.
Jim March
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Old April 26, 2002, 05:39 AM   #30
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Doing a BTT because I want to see how many hits this thread ended up getting .
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Old April 26, 2002, 05:53 AM   #31
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Very informative thread. Thank you, Mister March.

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Old April 26, 2002, 06:56 AM   #32
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Mr. March:

Thanks for sharing that; it is one of the most detailed, complete, and helpful posts on buying a quality used revolver. I just bought my first used gun with some, but not all (unaware of all of them!)of your criteria. Result? A real creampuff of a revolver!

I'm a native San Franciscan and recall Richmond had some of the more menacing neighborhoods in the bay area.......places where it was more than wise to be "packing the heat."
Jeff the 22luvr ><>
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Old April 27, 2002, 11:51 AM   #33
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Thanks Jim
This thread has been one of the more enlightining threads in regards to how to buy a used gun. I have used this info to get a couple of bucks off a few guns I have bought recently.

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Old April 27, 2002, 02:37 PM   #34
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2,554 hits. Looks like they have been lookin when we send them here.

Jim done good.

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Old June 18, 2002, 01:44 AM   #35
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Jim, I also check the top strap just above the barrel for flame cutting (more common in Magnum's that have had a steady diet of fullpower or +P/+P+ ammo) before or after checking end shake and cylinder gap.
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Old June 20, 2002, 12:36 AM   #36
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New Taurus 608 eval/possible problem?

Reentered as a new thread to avoid duplication.
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Old July 7, 2002, 05:02 PM   #37
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Dammit,...I think!

OK,...I've got this "new" S&W 629-4 44Mag Mountain Gun.
After reading the orig post by Jim, I'm a little worried that I bought a bad gun.

Cyl.Gap: .010" this in "full lock-up" as described by Jim.
(the .010" shim will force in on all cylinder hole indexing, the .011" will not)

fwd/backwrd play of cylinder: definately there, can hear slop when I move the cyln fwd/bkwrd. (maybe .001"-.004" play)

rotational movement When in "full lock-up", the cylinder rotational play is more on some cylinder holes than others. The play at best is .001"-.002" (pretty solid), the worst two positions are .003"-.005" play by my estimation (definite slop detected).

I'm mechanically inclined, what can a guy do to tighten the cyl gap to .005" (this would also help the fwd/bkwrd play of the cyl I'm sure) and how can I get the rotational play reduced?

..and yes I have a Brownells accnt!
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Old July 8, 2002, 11:30 PM   #38
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I don't claim to be a gunsmith. I don't know why that gun is so out of spec, but it is. If it was just "factory sloppy", the gap and front/back wiggle might be fixable with shims. If it got that way by some idiot "wildcatting" a 280grainer to 2,000fps or whatever, it could have a stretched frame, bent crane, God only knows.

The "checkout" isn't a gunsmith's diagnostics tool, it's a buyer's guide. If it was for gunsmiths, there'd be precision calibers and micrometers involved, laser bore-sight alignment tools, etc.

In your situation, I recommend at least an inspection by a qualified 'smith, figure out where you're starting from. Then, if you're going to wrench, you at least need a very good reference work with specs, tolerances, parts diagrams, blueprints, ETC.

This is a whole different arena than the "homebrew mods for Ruger SA" thread:

Real gunsmithing and minor parts-swapping are two totally different critters. Somebody who's a decent auto/motorcycle/whatever shadetree mechanic can do a bit of the former, with care, but for God's sake know your limits. If I swap grip frames on a Vaquero or something and get it wrong, it'll slowly shake loose, or the action could seize up. If something is BENT, the gun could turn into a freakin' hand grenade.
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Old July 10, 2002, 03:38 PM   #39
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S&W says "...within spec.."

Very unfortunate........
I called SW support to ask about the .010" gap between cylinder and barrel. The reply was "..our specs are .004"-.010".."


Well,...I'm gonna see if I can get an .011" guage in there ANYWHERE!!!!
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Old July 10, 2002, 04:57 PM   #40
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.01" is "in spec"?

Dear GOD.

This, ladies and gentlegunnies, is why the checkout is a good idea for NEW guns as well as used. 'Cuz in my mind, .01 is utter crap. In a 2" barrel .38, it could lead to so much velocity loss a hollowpoint won't open where it would in a tighter-gapped gun.

Allow me to rant for a sec:

We know that predators of all types are dissuaded from attack when they see a resolute defender instead of a helpless victim. The difference on the part of the intended victim is stark, and is difficult to fake. Doesn't matter if the assailant is human, canine or even ursine (bears have retreated at gunpoint too!).

The intended victim gains confidence in large part by just having the gun even if it ain't seen, or laying hand on it, or drawing as required. In that sense, it IS a "talisman" of sorts, something that affects your mindset at that most crucial juncture of your personal history.

A gun such as TVDean describes wouldn't instill quite as much confidence in me as a GOOD one would.

Sure, it'll probably do the job. Almost certainly. But...that's a bad moment to be having qualms, you know?

A *good* gun is worth paying for, one that's accurate and reliable and with good sights, even if never fired in anger - because it's quality WILL be used.

It'll be used to affect your mindset.

Thus endeth the sermon.
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Old July 12, 2002, 12:45 PM   #41
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I don't mean to distract from the great information in this thread, but I must post a follow-up on the gap issue with my 629-4

After cleaning the gun, I discovered that Ican insert a .011" guage between the cylinder and the barrel at two of the 6 cylinder holes. This would be outta-spec, no?

I call S&W to explain what I've discovered, and I get a short-fused response from the guy on the phone. He said I can't "..just force a .011" guage in there, that's not how we measure it....if it slides in there then it's outta spec.."
I told him that if I can GET an .011" in there at all, then there's 11 thousands clearance between the two. Where's the argument?

Anyway, I'm sending it in.....

(thanks for the space to vent)
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Old August 10, 2002, 11:03 AM   #42
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Thank you for this thread, because my dad just called saying he acquired a 'flea market' deal on a S&W .357 (probably a 686). Having never owned a revolver before, this will be most informative for him and myself!!!
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Old August 11, 2002, 02:56 AM   #43
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Side to side cylinder play......

I'm noticing that my Blackhawk (bought used about a month ago) has some side to side cylinder play when the hammer is cocked. None of my other revolvers do. At what point do I contact a gunsmith and have them check this out? Its only a small amount of movement, but its noticable. How much do they generally cost to remove the play in the cylinder?
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Old August 12, 2002, 02:50 AM   #44
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You don't check cylinder play with the gun COCKED. That doesn't matter, unless it's extreme.

What matters is how it reacts at "full lockup", hammer down and trigger back as it would be when it fires. Go look at the checkout again.
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Old November 14, 2002, 01:22 AM   #45
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Old November 14, 2002, 09:05 AM   #46
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excellent post. Is there anybody who could give detailed instructions for checking out a semi-auto? gun show in two weeks and I'm looking to get a practice .22.
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Old November 14, 2002, 11:05 AM   #47
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Jim - Many thanks for the guidelines!

Question: on a new and unfired S&W N-frame 44mag revolver, with the hammer down and the trigger not pulled, is .023" total rotational slop in the cylinder OK? Or is this a bit too much for a new gun? Thanks. adk
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Old November 14, 2002, 12:04 PM   #48
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.023 probably within spec according to it's mommie but...
Just checked the high mileage 29 on my belt and it has .012 slop.
Been used as a trainer and cary gun for over 20 years.

Have to watch the new ones very carefully.

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Old November 15, 2002, 11:44 PM   #49
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I have a S&W M66 that I just ran through the 'test'

cylinder/barrel gap is nice and tight. i don't have a feeler gauge handy, but it is tight enough that just a peice of paper slides through.

Rotational 'slop' in full lockup is pretty much nil, on all holes.

Timing appears to be great. All holes line up perfect with the barrel.

The one thing it seems to have failed miserable at (as mentioned above) is the front to back cylinder play. Mine has enough play that I can hear it as I move it back and forth.

I'll try to get some feeler gauges here in a bit, but is this something that will make the gun unsafe to shoot, or just hurt performance?
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Old November 16, 2002, 01:05 AM   #50
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Thanks Jim.

Gun show next weekend and I'm looking for a S&W 67.
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