N Frame cylinder gap?

[metalman60]

I have a model 24-3 , N-Frame Revolver. Originally sold as a Lew Horton Special. Caliber is 44 special. What is an acceptable cylinder gap on this revolver.?
Thanks Very Much-

 

[armorer951]

I believe the factory front gauge (barrel/cylinder gap) is stated as .004" - .012" at this point. My armorer's manual lists the recommended gap as .004" - .010", but other members here have reported that .004" - .012" is now acceptable, according to the Customer Service people at the factory.

Smaller the better, IMO, down to the .004" minimum.

 

[toroflow1]

I like to see no more than .007".

 

[stansdds]

Ideal gap would be 0.006", but S&W allows 0.004" to 0.010", and at times up to 0.012". Some people have even reported buying new revolvers with a 0.014" gap.

 

[steelslaver]

While it is some what dependent on ammo as a heavier bullet has more back pressure so more escapes at gap, powder burn rate etc. The longer the barrel the more time bullet is in it and the more tome gas had to escape. But from testing by "Ballistics by the Inch" a 4" shooting 158 grain lead SWC 357 gave at 10 shot average of 1197 with no gap at all, 1123fps with a .001 gap and 1104 with a .006 gap. A 6" with 0 gap got 1286, .001 got 1196 and .006 got 1178

So, You lose a bunch with just .001 gap then the amount of gap has way less effect. Because with a 4" the first.001 lost 75fps and the next .005 only lost 19fps only about 1/4 of what the first .001 lost. The 6" lost 90 fps with the first .001 then 18 fps opening the gap from .001 to .006. Of course a revolver will not function at all with .0000 gap and not for very well for long at .001.

It would be hard to convince me that the addition of another .004, making the gap a total of .010 would cost you more than another 10fps. Or that closing the gap to say .003 from .006 would can you more than 10fps. Most ammo has a velocity deviation greater than that.

I used to be more concerned about gap and prefer .004-.006 but after reading some actual testing I am not quite so worried about it.

I believe a good forcing cone is more important than the B/C gap.

 

[stansdds]

Yes, the biggest thing about the barrel-cylinder gap is that there needs to be enough for reliable operation.

 

[robertrwalsh]

Back in ancient days 0.004 - 0.006 was the standard if I recall correctly.

 

[metalman60]

Thanks everyone for the information. Pushing the cylinder of the model 24-3 all the way forward, the gap measures .008. Pushing the cylinder all the way rearward, the gap is .010. Does this translate to an .008 cylinder gap with .002 endshake?

 

[armorer951]

Yes sir, it does. You'll need that amount of endshake in the assembly to accommodate debris and lubricant, and for the cylinder assembly to rotate properly. (freely)

 

[stansdds]

Thanks everyone for the information. Pushing the cylinder of the model 24-3 all the way forward, the gap measures .008. Pushing the cylinder all the way rearward, the gap is .010. Does this translate to an .008 cylinder gap with .002 endshake?

That is about as close to perfect as you are likely to get without some true gunsmithing action. Yes, you have an 0.008" gap and 0.002" end shake.

 

[Benchrest1]

Last time I checked my best shooting 686 had a gap of .010.

 

[chief38]

IMHO .004" to .006" is perfect. Anything more than .007" is a bit excessive and should not be acceptable while anything under /.004" might cause a sticky cylinder rotation.

About 25 years ago S&W would deem .006" to be about the maximum.

 

[steelslaver]

Here is the real question. What will a gun with a .005 gap do that one with a .009 gap not do and visa versa???

I highly doubt that the increase in distance from cylinder to barrel does much to decrease accuracy and will cause less than 10 fps. As far as flame cutting up the top strap, I would think a tighter gap if anything would focus the blast in a tighter area and cause a slightly thinner but slightly deeper cut.

While I agree that .004-.006 is ideal, and anything over .010 is getting excessive, the extra .004 between .006 and .010 actually amounts to almost nothing as far as performance goes.

I have an older refinished M&P with a 4" barrel, I have been thinking of sticking a 2" barrel on. Maybe I should haul my machine rest, chronograph and barrel extension facing tool to the range. and See what changes when I open the gap from its present .006 to .008 then .010.

 

[BSA1]

A larger gap is important for reliable operation with lead bullets. I think the concern about tight b/c gap comes from gun 'riters hyping it up.

I have two Ruger Vaqueros that I heavily used in SASS and CMSA. The face of the cylinders would get fouled with lead residue buildup. The b/c gap on one new out-of-box measured .003" from one side and only .001" from the other! I had the b/c gap on both of them cut to .008" and have never had any reliability issues. I still own both of this guns and would not hesitate to carry them for self-defense.

Much ado about nothing.