Excessive barrel/cylinder gap?

[dg31872]

I just got a new in the box Ruger Single Seven in 327, and the gap between the barrel and the cylinder seems excessive. I have not used a feeler gauge yet, but I have more lost motion than I like.
Any advise about how much is excessive and how much is just factory acceptable?
And the best way to measure the gap if just sticking the feeler gauge in the gap until the next size up does not fit?
Thanks in advance.

[JSnover]

Yeah. I measure mine with a fired case in the top chamber (leave the spent primer in), holding the trigger back so the hammer is holding the cylinder forward. I have heard of gaps up to .011" but don't have enough revolver experience to comment on your 327. Best guess from me would be .003-.008"

[osteodoc08]

Anything over .006" is excessive to me, but I "heard" that manufacturers allow for .008" to be working acceptable limits. I prefer 0.003-0.004" on my working guns, but have some in the .005-.006" range that are good shooters. A competition gun id want the gap as small as possible but remain functional through the match.

[dg31872]

Thanks for the help.

[Outpost75]

Check the barrel-cylinder gap WITH EMPTY BRASS IN THE GUN!

PASS dimension is the largest feeler gage size you can insert between the barrel and cylinder, protruding from both sides of the frame window, which permits pulling the trigger six times to rotate the cylinder through a full revolution without binding up.

HOLD dimension is the size which in the same test condition as above causes the cylinder to bind before completing a full revolution, with fired brass in the gun (substitutes for "rear gage").

END SHAKE or END PLAY is the difference between two HOLD measurements, taken both with, and without "rear gage" in place.

New builds before proofing min pass 0.003/hold 0.004

After proofing max pass 0.006/hold 0.008

Customer service max pass 0.007/hold 0.009

Cylinder gap over 0.012" should not be fired as you may stick bullet in barrel.

End Shake over 0.003" stretch crane arbor then recheck gap.

If HOLD gap after over 0.009 refit with "long" cylinder.

Current specs may vary, but this is how I built them in the 1980s.

[JSnover]

Thanks Outpost 75!

[dg31872]

Good. Thank you, Outpost 75.

Now I have to see if my feeler gauges go that small.

[jmort]

Very interesting thread
The cylinder gap on my Freedom Arms 93 is really tight
I have never seen any revolver that tight

[FergusonTO35]

Most folding leaf automotive feeler gauge sets go that small, mine do. I have a Rossi 461 .357 with 3" barrel that I got LNIB for $220.00. It is surprisingly nice looking and shoots well but is cursed with a .012 gap. I sent it back to Rossi, who knows if they will do anything with it. Biggest thing I don't like is that you start losing serious velocity with a gap this big. That particular Rossi gives up around 120-130 fps with identical loads to my S&W 10-5 with 4" barrel and very snug .002 gap.

[Outpost75]

Very interesting thread
The cylinder gap on my Freedom Arms 93 is really tight
I have never seen any revolver that tight

Too tight and gun will freeze up when it gets dirty or hot. Tightest gun I have which "works" is a customized .44-40 Ruger with Bowen cylinder which is pass 0.002/hold 0.003. With "clean" shooting ammo it works fine, but not with black powder.

[FergusonTO35]

I never put more than 50 rounds through my wheelguns without cleaning. I always scrub the barrel to cylinder area well.

[Three-Fifty-Seven]

.....

[Alstep]

I bought a S&W 19-3 last year from someone I know well. He bought it new and never shot it much. It's in absolutely pristine condition, everything nice & tight. Never thought to check the gap when I bought it. Turns out it's .013!!! Seams to shoot .38's real well.

[Outpost75]

I bought a S&W 19-3 last year from someone I know well. He bought it new and never shot it much. It's in absolutely pristine condition, everything nice & tight. Never thought to check the gap when I bought it. Turns out it's .013!!! Seams to shoot .38's real well.

I would send it back to S&W and have it corrected. I find it hard to believe they would ship one that loose.

[Chill Wills]

Check the barrel-cylinder gap WITH EMPTY BRASS IN THE GUN!


That is a pretty good piece of information!

The whole page is worth printing off and going into my shop notes and cheat sheet binder but that one part is really good.

[Outpost75]

That is a pretty good piece of information!

The whole page is worth printing off and going into my shop notes and cheat sheet binder but that one part is really good.

Less expensive than a set of six Go headspace gages too!

[Oklahoma Rebel]

I have a question, when someone says they have had a revolver "tightened up" by a gunsmith, what is involved in that process, and is it the same process with a single action? thanks a lot!-Travis

[KCSO]

The old S and W specs were 6 to 9 thou. I would want 4 to 6 as ideal and no larger than 10 at most.

[Outpost75]

I have a question, when someone says they have had a revolver "tightened up" by a gunsmith, what is involved in that process, and is it the same process with a single action? thanks a lot!-Travis

"tightening up" means different things to different people and can be a catch-all serving as a coverup for jackleg Bubba work...

Revolver annual inspection and maintenance, as was done by police armorers back in the day when your life depended upon a wheelgun going "bang~!" every time, included at minimum, the following, which IF you pay attention, you will know how to inspect a used gun before buying:

Open and close cylinder, confirm proper function of thumbpiece to release cylinder and both front and rear cylinder positive lockup when closed.

Verify center free pin movement and return.

Visually inspect fit of yoke or crane at front of frame and cylinder for gaps.

With cylinder open, spin cylinder and watch ejector rod for wobble

Check ejector rod is tight, not loose on threads, inspect front end of center pin for peening, verify that ejector rod functions correctly full stroke and returns positively

Close cylinder, feel for cylinder end shake both with and without empty brass in chambers

If any wobble, disassemble cylinder from yoke, check crane or yoke alignment with gage and correct.

Visually inspect locking bolt notches for peening

Pull revolver through rapidly DA while checking for positive trigger return and positive lockup at each charge hole, noting any failure to "carry-up," or any "throwby" i.e. over-rotation of the cylinder failing to lock up and rotating past a chamber, or sideways wobble.

Visually check bolt or cylinder stop function at every charge hole and check cylinder for wobble each charge hole.

Cock each chamber SLOWLY in SA with the weight of gun resting in the palm of hand for drag, note any failure to "carry up" and for bolt or cylinder stop to engage locking bolt notches prior to full cock.

Check hammer for push-off from full cock position.

Drop hammer, hold trigger back, check cylinder for wobble both sideways and fore & aft

With hammer down and trigger held back again check cylinder wobble, observe hammer nose driven protrusion and retraction below flush with recoil plate as trigger allowed to rebound forward.

Check cylinder gap, above all cylinder must not strike barrel when closed!
min pass 0.003", max. hold 0.008" with brass in cylinder

Max end play 0.002, difference between "pass" dimension taken twice with and without brass in cylinder.

"Tightening up" to adjust timing and indexing may be as simple as peening the hand a bit longer so that a charge hole which is "slow" carries up, and possibly peening the locking bolt notches in the cylinder to reduce side play.

Reducing cylinder end play involves stretching the crane to hold the cylinder back. This also increases cylinder gap, which if it then becomes over 0.008" then requires either refitting a "long" cylinder, or setting the barrel back a thread and resetting the gap to factory specs.

A simple clean, inspect and tweak not requiring fitting any replacement parts runs $100-150 most places.

A duty refurb which includes machine work needed to set the barrel back and refit, aligning the crane, correcting endshake, adjusting timing, replacing worn springs, targeting and checking hammer throw and striker indent on the government gage with copper crusher runs $250-300. Today you rarely find smiths who actually check striker indent on carry guns! A much better "filter" than some school certificate on the wall. It means you have an APG or FLETC certified inspector who was trained at the factory especially for the Feds.

If the rework requires heavy duty cleaning, such as ultrasonic followed by hot acid pickle to remove active rust, as from sweat or saltwater immersion, or hand carding off internal rust, then replacing and fitting either a new cylinder, or barrel or internal parts and rebluing, the bill can easily run $500-600 if done professionally by a Pistolsmith Guild smith of national reputation.

[Oklahoma Rebel]

wow, thanks for such a detailed, thorough answer! say for instance, a super Blackhawk .44, or redhawk 44, that isn't abused, ( no super heavy, or super high velocity rounds) about what kind of round count do they get before needing such attention? I think I have heard everything from 4-5 thousand to 10,000 rounds. is that accurate?

[silhouette_shooter]

S&W allow for up ten thousandths. Freedom Arms won't go near that, mines approx .003 general consensus is not more than .006.

[Outpost75]

FYI for anyone who hasn't visited the page and read it, but the revolver inspection instructions are now a sticky and have been revised based on helpful comments I've received from professionals in the trade who lurk here:

http://castboolits.gunloads.com/showthread.php?353160-Revolver-Inspection-The-Right-Way-aka-Wheelgun-101