Model 15-3 Barrel Gap .021"

[b3rad]

I bought a Model 15-3 from Cabela's last weekend that I plan to play around with for IDPA. I was looking it over carefully and I noticed that the barrel-cylinder gap is pretty big - I measured about .021".

I've fired it once so far, putting around 24 rounds through it and it shot very accurately.

What are your opinions on this barrel-cylinder gap being so big? Is it a potential safety issue?

 

[b3rad]

BTW, if anyone can tell me the age of my "new" 15-3, I'd appreciate it. The serial number is 13K7XXX.

Also, I didn't put the full serial number because I notice others don't. What's the reason for not publishing the full serial number? What can someone do with this information?

 

[Robinett_11B]

Also, I didn't put the full serial number because I notice others don't. What's the reason for not publishing the full serial number? What can someone do with this information?

It's really not a big deal. I think the worst someone could do is report your gun's serial as stolen and try and cause trouble for you. I never had any issues with posting full serial #'s, nor have I ever heard of anything negative coming as a result of it. I think it's just a tinfoil hat thing.

 

[OC]

Not posting the last 2 or 3 numbers of the serial number is kinda like not putting all of the numbers of your credit card on the internet. No telling who has access to this information, and for what reason. If I were to claim a gun lost in a burglary, and used your serial number on the insurance claim, it would show up as a legitimate number, but if you went to sell it through a FFL, it would show up as stolen. Guess what happens next? Better safe than sorry.

 

[OC]

BTW my info says your mfg date is 1977.

 

[mtgianni]

If it shoots accurately enough for you the BC gap is one you will live with. Let professor gun teach you what he wants.

 

[Decker]

My personal experience over the years is that a "tight" cylinder gap is highly over rated.
If it's as accurate as you expect it to be, then leave it alone.

Much more important than cylinder gap is proper alignment of the cylinder to the barrel on lockup. That's where you will find accuracy and spitting problems more than with a wider cylinder gap.

I've got all three Dan Wessons (.22, .357, & .44 Mag), and each of them call for using the .006 cylinder gap shim when installing barrels, but I have gotten to just setting the gap by eye without using the shim at all and haven't noticed any difference in accuracy.
That said, my job has given me a trained eye where I can recognize very small tolerance differences, so I know that I'm setting the Dan Wesson gaps anywhere from maybe .008 to .015 or so (maybe up to .020), and they shoot just fine.
All I do is just make sure that the cylinder clears the barrel, and I'm good to go.

 

[srgvaz]

If it was mine and the gap was that LARGE I would not hesitate adding a shim or two...

 

[H Richard]

Just curious where you add a shim that will "reduce" the B/C gap? In my limited gun-smithing activities I thought the only way you could reduce the B/C gap was to set the barrel back.

 

[b3rad]

I appreciate the replies.

I'm also curious about the shim comment - I thought the only way to reduce the gap was to set the barrel back too.

 

[Nevadadvx]

It's really not a big deal. I think the worst someone could do is report your gun's serial as stolen and try and cause trouble for you. I never had any issues with posting full serial #'s, nor have I ever heard of anything negative coming as a result of it. I think it's just a tinfoil hat thing.

I agree. I think its like people that block out the license numbers on their cars when posting pics of them. I mean c'mon, we see license plates every day.

 

[srgvaz]

I appreciate the replies.

I'm also curious about the shim comment - I thought the only way to reduce the gap was to set the barrel back too.

YouTube - Gunsmith - Fix excessive cylinder endshake in S&W revolver

 

[srgvaz]

I agree. I think its like people that block out the license numbers on their cars when posting pics of them. I mean c'mon, we see license plates every day.

Even being that careful can still get your information stolen. It's personal preference, but there's no such thing as being to careful online.

 

[john traveler]

Indeed there IS another way to decrease the barrel-to-cylinder gap, but it is not recommended:

Cut back the crane barrel, and then add shim washers until you get the desired b-c gap.

Remember that b-c gap, cylinder end shake, and cartridge rim-recoil shield clearance are all regulated on a frame at time of assembly. Change one of these, and the other clearances will change also.

 

[Alk8944]

Indeed there IS another way to decrease the barrel-to-cylinder gap, but it is not recommended:

Cut back the crane barrel, and then add shim washers until you get the desired b-c gap.

Remember that b-c gap, cylinder end shake, and cartridge rim-recoil shield clearance are all regulated on a frame at time of assembly. Change one of these, and the other clearances will change also.

This thread gets sillier and sillier. Would you like to explain where you would shim a S&W to move the cylinder forward????? Are you going to cut the yoke barrel to let the cylinder move forward, then add end-shake bearings (shims) to re-set the end-shake? Why? You will be right back where you started!

There may be more to this revolver's problems than are readily apparent from the original post. There are probably several areas to address to get it right mechanically.

(FWIW, I know how it could be done, and maybe you didn't explain yourself properly, but as an alternative to doing it right by setting the barrel back would amount to a hack-job.)

If there are any questions, read the sig line.

 

[Rimbaud]

What is involved in setting the barrel back? Do you shave metal off the front of the frame?

 

[k22fan]

This thread gets sillier and sillier. [...]
If there are any questions, read the sig line.

Obviously your sig line reveals that you're just old fashioned. It's simple. After shortening the yoke solder the washers onto the back ends of your cases to hold her foward.

What is involved in setting the barrel back? Do you shave metal off the front of the frame?

Metal is lathe turned off the barrel's shoulder so it can screw into the frame just a tad short of a full revolution so it will turn up straight with correct torque, its breach end is shortened to set B/C gap and its forcing cone is recut. This is what we have neighborhood gunsmiths for, but factory repair is another option.

 

[Rimbaud]

Metal is lathe turned off the barrel's shoulder so it can screw into the frame just a tad short of a full revolution so it will turn up straight with correct torque, its breach end is shortened to set B/C gap and its forcing cone is recut. This is what we have neighborhood gunsmiths for, but factory repair is another option.

Thanks. How much linear movement of the barrel does one barrel turn give you?

Does this process normally necessitate a reblue?

 

[k22fan]

Thanks. How much linear movement of the barrel does one barrel turn give you?

Does this process normally necessitate a reblue?

Linear movement is usually calculated with a thread gauge and a little math. A K frame barrel probably moves a little less, but an N frame barrel moves 0.027" per revolution if I recall correctly.

There's no reason to reblue because the only visible surface that metal gets removed from is the breach end of the barrel.

In the last year my smith has charged me $90 and $110 dollars to change barrels which is the same work. The $20 difference was for the extra labor involved installing a barrel with a front sight that was part of the barrel forging. The sight prevented inserting the muzzel into the lathe's chuck so the barrel had to be turned between live centers. I'm sure a nationally known smith would charge more but you could only hope their work would be as good.

I find it usfull to have a working relationship with some local craftsmen, including a gunsmith.

Gil

 

[haggis]

I bought a Model 15-3 from Cabela's last weekend that I plan to play around with for IDPA. I was looking it over carefully and I noticed that the barrel-cylinder gap is pretty big - I measured about .021".

How you measured the 0.021" B/C gap will determine how you fix the problem. The correct way is with the cylinder held forward. Then you measure it with the cylinder at the rear. The first measurement is the B/C gap, and the difference between the two measurements is endshake. If endshake is more than about 0.002", that has to be corrected before B/C gap can be set.

I apologize if you already knew this, but many people don't, and it can lead to different kinds of responses with each solution dependent on how the responder interpreted your measurement.

If the endshake is excessive, that can be corrected by placing shims between the cylinder and the yoke end (there are other methods). That also increases B/C gap. Sometimes you get lucky, and taking endshake out also exactly fixes B/C gap. In any event, first you remove excessive endshake. If the B/C gap is then more than 0.010"-0.012", you need to set the barrel back one turn, cut the barrel face to get correct B/C gap of about 0.006", and re-cut the forcing cone. If the B/C gap is less than 0.004", you cut the barrel face back to set B/C to 0.006", and whether or not you re-cut the forcing cone depends on how much you cut the barrel.

It sounds like you are in for a barrel setback no matter how you measured the gap, and unless you have done this before and have the right tools, turn the gun over to a competent smith, and let him fix it.

Buck