Cylinder gap on Highway Patrolman M28

[Doug.38PR]

I just measured the gap on my cylinder/force cone on my 6 inch Model 28 Highway Patrolman. It measures as .017 or even .018 (I can get the .018 inch in there if I force it a little).

I read on another thread that S&W spec is between .006 and .010. Is this correct? If so, that would mean mine is WAY too wide.

Ever since I started chronographing my 4 inch Python and my 6 inch Highway Patrolman, I've been shocked that my shorter Python can match or exceed my 6 inch S&W. THIS might explain why.

How can I have this corrected? Can a local gunsmith do it? Do I need to send it to S&W? What kind of money are we talking here?

 

[44wheelman]

I'm no gunsmith nor master machinist, but I do have access to a machine shop; and I managed to fit a 44 spl to an abused 38/44 frame, and rechanbered the cylinder to 44spl.

So a local gunsmith should be able to do it- just depends on his machining access & experience. It will need the barrel shoulder turned back one full thread, eliminate all the end shake in the cylinder, and set the barrel length to the desired gap. I was shooting for .004, and was able to get .005" so I was happy.

 

[chief38]

In the good ole days, S&W's B/C Gap spec range was .003" - .006". Anything out of that range was not correct or acceptable. TODAY, their spec's for a B/C Gap is up to .012" which to me is NOT acceptable, but I do not own the S&W Corp. A Gap of .017" - .018' is ABSURD and if it were mine it would already be in the mail back to Springfield!

My personal favorite is around .004" to .005" and I guess I am lucky since most of mine are actually about that, with a few at .006" but no more than that. How Smith could say .012" is acceptable is beyond me since just a few years prior only HALF that was acceptable. I suppose they are really getting sloppy and complacent or simply don't give a damned anymore.

A large B/C Gap like yours will cause lead spitting, more leading, loss of velocity and more erosion of the Forcing Cone. I would never want a Gap less than .004" because of possible cylinder binding when the gun is dirty. A revolvers Cylinder face doesn't take much to build up lead and carbon and too tight is no good either.

 

[Rick_A]

Endshake and B/C gap are two different conditions with different techniques for repair.

 

[chief38]

Rick A is correct and reducing endshake (common fix is .001" or .002" shims or a combination of them) usually increases B/C Gap! Two different problems. Yes, endshake can also be reduced or almost eliminated by the process of stretching although I personally prefer the shims.

B/C Gap is fixed by refitting barrel to frame so that Forcing Cone is closer (or has less gap) to the cylinder face.

 

[Doug.38PR]

Excessive endshake is fixed by "stretching" the barrel of the yoke a little bit (about .003 in my revolver). I did it this afternoon on a Model 27-2. It took 10 minutes. Before the repair, the cylinder could move forward and contact the forcing cone, causing the trigger pull required to get past the hard spot to be quite excessive. You use a tool that looks like a tubing cutter, but the blade has been dulled. Or, you can peen around the circumference of the yoke barrel slightly. Either way, you need to reinforce the yoke barrel while stretching by inserting a yoke/barrel alignment tool inside the barrel, reinforcing it so it does not bend from the forces applied. The B-C gap is now .003, and the gun shoots great! I test fired it 50 times this afternoon, right after I fixed it.

Other types of endshake, the type that requires the button shortened on the yoke, can be corrected using the Power Custom endshake washers. I have not found any washers that can be used instead of stretching the barrel of the yoke.

For somebody familiar with the insides of old S&W revolvers (before MIM parts), who has the tools, it is a quick and simple job, no parts required.

No barrel turning required. Sorry, 44wheelman, that is not the technique.

The Kuhnhauser manual describes the procedure. Brownells sells the yoke barrel stretching tool, yoke alignment tool, Power Custom washers, and much more.

Well, I there is almost no end shake. That cylinder is pretty solidly in place

 

[flintsghost]

Disregard the post by Collects. With all due respect he doesn't understand what the question is. In order to reduce the barrel/cylinder gap on a revolver with no other problems, you must remove the barrel. Chuck it in a lathe and turn the barrel shank back a few thousands and refit everything. The barrel must be indexed and then the gap fitted properly. When I went to armorers school the gap was .003 - .010. Now S&W has increased that spec. After you get the barrel/cylinder gap right and my opinion is .004 is right to start...then you will probably have to refit the extractor rod and maybe the center pin because you will have moved the lock toward the frame by the same amount that you removed on the lathe. There are specific tools that are available to recut the forcing cone which also has to be done and also for facing the barrel. The tool to face the barrel is the best to adjust the gap to .004.

This is not a job for most local Smiths who have no formal training or machine experience. If you take it to one of them to have it done, you can plan on having your revolver ruined. However there are competent smiths who are also machinist trained that can do it. S&W can do it but may not adjust it to minimum. Also, if you send it to S&W and they have trouble getting the barrel off, you won't get your gun back.

 

[andyo5]

My understand that a competent gunsmith can shim something (the yoke?) to reduce the gap.

 

[Doug.38PR]

Disregard the post by Collects. With all due respect he doesn't understand what the question is. In order to reduce the barrel/cylinder gap on a revolver with no other problems, you must remove the barrel. Chuck it in a lathe and turn the barrel shank back a few thousands and refit everything. The barrel must be indexed and then the gap fitted properly. When I went to armorers school the gap was .003 - .010. Now S&W has increased that spec. After you get the barrel/cylinder gap right and my opinion is .004 is right to start...then you will probably have to refit the extractor rod and maybe the center pin because you will have moved the lock toward the frame by the same amount that you removed on the lathe. There are specific tools that are available to recut the forcing cone which also has to be done and also for facing the barrel. The tool to face the barrel is the best to adjust the gap to .004.

This is not a job for most local Smiths who have no formal training or machine experience. If you take it to one of them to have it done, you can plan on having your revolver ruined. However there are competent smiths who are also machinist trained that can do it. S&W can do it but may not adjust it to minimum. Also, if you send it to S&W and they have trouble getting the barrel off, you won't get your gun back.

Wow. So what is my solution? I can't rely on local smiths or modern smith and wesson

 

[steelslaver]

My understand that a competent gunsmith can shim something (the yoke?) to reduce the gap.

You can shim out end shake, the back and forth movement of the cylinder on the yoke and also the yoke to frame fit. But the barrel to cylinder gap can not be shimmed tighter. The cylinder to recoil shield is fixed by the extractor center riding lightly against the center of the recoils shield with end shake correct. You can not move the cylinder forward and even if you could it would increase head space as well as cause the hand to engage the the ratchet incorrectly. The only correct fix is as stated. Removing .0277 off the barrel shoulder. This is enough for 1 turn of the 36 to the inch barrel threads. Then the barrel forcing cone face needs enough removed to get the proper gap after end shake is correct. Then you must recut the forcing cone as some of it has been removed. As you moved the locking lug on the barrel back .0277 you must remove this much from the extractor rod assy for it to close and lock properly if it was in spec before you started.

Been there done that.

 

[Nightowl]

Doug: I'm sure there are plenty of folks around that can do the required work to bring your 28 back within specs. However, if it were mine I would call Smith & Wesson and see if they would fix it. They do know how and I believe they will charge you less than sending to anyone else. Their shipping costs are reasonable as well. I sent a gun back this spring and the cost was very reasonable and it was not gone all that long.

 

[Doug.38PR]

Doug: I'm sure there are plenty of folks around that can do the required work to bring your 28 back within specs. However, if it were mine I would call Smith & Wesson and see if they would fix it. They do know how and I believe they will charge you less than sending to anyone else. Their shipping costs are reasonable as well. I sent a gun back this spring and the cost was very reasonable and it was not gone all that long.

Well, are they really going to be "in specs". Apparently what was in specs for this particular gun back in the 70s .006 is not in specs now .012

 

[bgrafsr]

Contact Andy Horvath, Lagrange, Oh. 440-458-4369. He can and will fix your gun and will make the B/C gap to what you want, which should be .004". He is an excellent gunsmith.

 

[Doug.38PR]

Has anyone here ever used Jim Clark of Clark Custom near Shreveport/bossier city, Louisiana for your SW needs? Think they could handle something like this?

 

[Hapworth]

Has anyone here ever used Jim Clark of Clark Custom near Shreveport/bossier city, Louisiana for your SW needs? Think they could handle something like this?

Clark Custom's reputation for S&W tuning -- and all manner of gunsmithing in general -- is superb; if they're near you, you're a lucky man.

 

[Doug.38PR]

I just spoke to Clarks. Told them the situation with the gun. They were pretty skeptical. They said they could do it, but it would be spending a great deal of money for something that may or may not change anything in regard to performance of the gun. Told them I might still bring it by. I live about 2 hours away and drive through there frequently anyway. They seemed to be under the impression that the factory doesn't handle a lot of those older guns. And from what people have told me here, the factory might not even take it to true original specifications.

 

[Doug.38PR]

The process needed for correcting this, could it take away finish, edges and make the barrel fit look uneven or off. In other words: will anything be noticable or will, properly done, will it come away looking the same?

Also, as things are, the gun is out of proper specs. Doesn't that affect proper function as well as velocity?

 

[reddog81]

Also, as things are, the gun is out of proper specs. Doesn't that affect proper function as well as velocity?

How does the gun shoot? Does the large B/C gap effect the function on your gun? No offense, but we have no way of knowing how your gun functions.

How you owned it since it was new? Is there any chance the barrel was replaced at some point?

 

[chief38]

At this point I would suggest letting an outside Smith who has a stellar reputation do the job since I believe your age M28 is not under lifetime warranty. So if you have to pay for it you might as well get the best you can afford. I no longer think the Smiths at the Factory are top notch as they once were. Many of the older and more knowledgeable Factory Smiths are long gone.

 

[steelslaver]

If done correctly it should look the same. The hard part when I did it was chucking the barrel up in a lathe. Because the barrel isn't round I used a 4 jaw chuck and copper shims to prevent any mars. Took a lot of messing around to get it perfectly centered.

If I did it again I think I would make a brass piece. Start with a 1" piece of brass, using a center on the tail stock and turn about an 1" more than the barrel just small enough that the barrel barely slid on then thread the end to 5/16 NF. Slide the barrel on and then use a brass washer and a nut to tighten it up and hold the barrel for turning. Set my center and dial indicator then turn off the shoulder using very light cuts to get me there.

How does anybody else do it????

I don't do any work for others. I just like to make the guns I want like I want them.