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Posted: 12/26/2005 3:19:48 PM EDT
What would it take for me to replace the barrel on a S&W model 10-5? Do I just remove the pin above the barrel and screw out the barrel?

Link Posted: 12/26/2005 4:49:52 PM EDT
[Last Edit: 12/26/2005 4:55:47 PM EDT by dfariswheel]
Honestly, here's what you need to change out a revolver barrel.

1. A GOOD replacement barrel. Many used barrels are not usable for reasons running from them having something wrong with them to start with, to having been damaged when an unqualified person removed them. MANY barrels cannot be used, so you MUST know what to look for when buying one.

2. A set of special barrel blocks, usually brass, aluminum, or hard plastic.

3. A frame wrench, and a special pair of plastic frame inserts made to fit THAT specific brand and size of frame.
Helpful hint: The old gag of locking the barrel up in some wooden blocks, shoving a hammer handle through the frame, and "twisting the frame off" is just about 100% guaranteed to ruin the gun.
This little technique will either spring the frame, or will cause the frame to crack through the bottom of the barrel thread section.
No BS, more good guns have been ruined by this than just about anything else.

4. A special (EXPENSIVE) cutting tool that works down the bore to set the barrel-cylinder gap.
This cannot be done right by using a hand file.

5. A special (EXPENSIVE) cutting tool that works down the bore to re-cut the forcing cone in the rear of the barrel. NO other tool can do this.

6. A special (EXPENSIVE) gage that's used to gage the forcing cone.
The forcing cone is a CRITICAL part of the revolver, and if the forcing cone is JUST slightly too big, or too small, accuracy is GONE, and the revolver will spit lead.
The difference between too big and too small is TINY.
The critical measurement is the outer diameter of the mouth of the cone, NOT the depth or taper.
This CANNOT be "eye balled" and even a used barrel requires re-cutting.

When working with the forcing cone on a new barrel, the cone must be cut to spec.
When working with a used barrel that's ALREADY been adjusted to fit a different frame, either the cone must be re-cut, OR the barrel has to be trimmed on the lathe to set the barrel back one thread, THEN the cone has to be properly cut.
This depends entirely on what you've got in a used barrel.

7. The use of a lathe to trim the barrel shoulder so the sight will be at 12:00 top dead center when the barrel is properly torqued.

8. The knowledge of how all this tooling is used to insure the new barrel fits and is adjusted properly.
Do it wrong, and you've just ruined a good gun.
Revolver barrels are NOT just pieces of threaded pipe that can be screwed on and off at will.

My advice: Send the gun in to S&W. They have the tooling and knowledge of how to do it RIGHT.

My 30 years experience as a pro gunsmith: Do it yourself at home with "expedient" tooling, and kiss your gun good by.

Sorry, revolver's are almost 100% hand fitted items, and the barrel is strictly a hand fitted proposition.
If it isn't perfect, the gun is absolutely no good and won't shoot worth a damn.

Link Posted: 12/26/2005 6:00:03 PM EDT
dfariswheel,

Thanks for saving me from making a big mistake.

jim
Link Posted: 12/26/2005 9:55:59 PM EDT
You're quite welcome.
I unfortunately sometimes go overboard when answering this question, due to having seen the results of home barrel work too many times.

It's just that people don't realize how much is involved.
Link Posted: 12/27/2005 7:57:29 AM EDT
I don't think you went overboard at all. You laid out chapter and verse, cogently and concisely. It was a real education. I thank you, too.
Link Posted: 12/27/2005 8:20:13 PM EDT
[Last Edit: 12/27/2005 8:21:22 PM EDT by Striker]
Link Posted: 12/28/2005 6:15:31 PM EDT
Here's the actual process.

First, you check out the replacement barrel to make sure you have a good one.
MANY barrels bought from parts houses, gun shows, or ESPECIALLY from Ebay have some defect or damage.
Usually they were removed by someone with improper tools and damaged, or had a problem to start with, which is why they were removed in the first place.

Remove the old barrel using the barrel blocks, (most of us make our own from aluminum or plastic), and the action wrench with the plastic inserts that fit THAT specific brand and size frame.

Clean up the frame's threads with a tap used as a "chaser", then brass brush them with solvent to clean.

Test fit the new barrel to judge how much must be removed from the shoulder to allow the barrel to torque up properly, AND to have the front sight at 12:00 top-dead-center.

If necessary, clearance cut the lower shroud to clear the frame slightly.

Trim the barrel on the lathe.

Coat the threads with anti-seize or lube.

Install using the barrel blocks and frame wrench. Turn in too far by ANY amount, and the barrel has to be set back one thread and refitted.

Once the barrel is in, check to see how much pre trimming of the rear of the barrel is required to allow the cylinder to JUST BARELY close.

Trim it with the down-the-bore cutting tool.

Gage the barrel/cylinder gap, then use the tool to cut the barrel to allow the gap to be about perfect at .005" gap.

Use the forcing cone plug gage to measure the forcing cone's outside mouth diameter.

Use the down-the-bore tool with a tapered cutter to cut the forcing cone to the correct spec, per the gage. (You can use different taper cutters to set the gun up for lead bullets, jacketed, or a good compromise which is the factory taper).

Use a brass tapered lap and fine grinding compound to lap the cone to a smooth finish.

Clean up, then test fire to insure accuracy and function.

All this assumes the gun is in proper adjustment and has no problems like cylinder end shake, or alignment problems.
Link Posted: 12/29/2005 11:53:12 AM EDT
[Last Edit: 12/29/2005 11:53:28 AM EDT by Striker]
Link Posted: 12/29/2005 6:04:39 PM EDT
Factory NEW barrels usually stop well short, allowing you to trim a small amount of the shoulder off to give the correct draw for torquing, and have the barrel at top-dead-center.

USED barrels are another story. Usually they require cutting the barrel back one complete thread, to both give the correct draw, AND to allow setting the barrel/cylinder gap.

Getting the correct draw is a matter of experience in knowing just how much to remove without going too far.

So is pre-trimming the rear of the barrel to allow closing the cylinder.

Cutting the barrel/cylinder gap and re-cutting the forcing cone is a matter of not getting carried away, and making good (and often) use of the gages.

Link Posted: 12/29/2005 6:36:23 PM EDT
Link Posted: 1/1/2006 10:39:37 AM EDT
Good response dfariswheel. Charles the Gunsmith.
Link Posted: 1/2/2006 8:57:27 AM EDT
Monday, January 2, 2006

I would contact the Smith & Wesson factory and make arrangements for them to replace your barrel.

Take care,

MP5 Machinenpistole
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