M36 clone cylinder dragging on barrel

[swampjam]

I have an INA Tiger 38 Spc that is a clone of a S&W M36. After firing around 8 to 12 rounds, the cylinder starts dragging against the barrel. I think it is excess endshake causing this and want to install shims. Do y'all think S&W J frame shims work in this revolver? Do you think it is some other problem? Feeler gauges measures zero to .012 gap.

PS - I know this is not a S&W gun but I bought it on impulse because it was kind of pretty.

 

[snubbiefan]

0-.012? Did you make the measurement with the gun loaded? The rims ride against the recoil shield (unless it has a recessed cylinder) and it needs to be loaded and pushed back against the shield to take this measurement.

It just seems a bit odd that it would be binding with a .012 gap loaded and the cylinder pushed all way back against the shield. Sounds to me more like a poor fitment of the yoke and cylinder, or forcing cone (barrel) set too deep. No way should you have zero BTCG in any revolver with the cylinder pushed forward.

 

[steelslaver]

That's to sloppy. I take it you are measuring with the cylinder pushed back and then forward? You should have cylinder/barrel gap of at least .004 for reliability and anything over .006 is getting to be to much, IMHO. I hear that S&W now accepts some what larger gaps.. The shims are cheap and it couldn't hurt to try them. I would hate to try to modify the shims as they are very easy to damage. You will need to remove the ejector rod assy to install. Keep adding them until the cylinder has less that .002 end shack then remeasure with cylinder pressed forward. I would suspect your going to have a pretty big gap once you eliminate the end shake. .010-.012 would make the gun loud and lose some velocity. This could be eliminated by removing the barrel and taking small amounts off the barrels shoulder where it meets the frame until the barrel will make 1 complete revolution. If they used S&W's 36 threads to the inch you need to take off .02777 for 1 turn. This would take a lathe and very good set up. I have never tried it and wouldn't want too. I can think of a couple other ways to do this also, but all would be difficult to do well. I have fit several barrels but never had to do that or started with new barrel material, turned the threads long then took off from the cylinder end of the barrel to set the gap and then done the forcing cone, made and installed the extractor rod lock assy and front sight.

If you are measuring this 0-.012 clearance with the cylinder pressed back and rotating you have a very out of square cylinder. A bent yoke or yoke tube would cause a square cylinder to measure near the same cylinder/barrel gap per each hole, but be tighter on one side or the other or top and bottom.

The rims of the cartridges should not be what establishes this gap. With the cylinder shoved all the way to the rear there should also be a slight clearance between the cartridge heads and the recoil shield. The cylinder headspaces on the circle of metal near its center. You should measure about .004-.008 between the cartridge head and the area of the shild where the firing pin is. USE A EMPTY CARTRIDGE and feeler gauges to check this.

 

[Hapworth]

0-.012? Did you make the measurement with the gun loaded? The rims ride against the recoil shield (unless it has a recessed cylinder) and it needs to be loaded and pushed back against the shield to take this measurement.

One definitely wants to measure b/c gap with the cylinder held back, but I've never heard of measuring it with a loaded cylinder (snap caps, hopefully ), including in the Kuhnhausen book. You sure?

 

[Hapworth]

You should have cylinder/barrel gap of at least .004 for reliability and anything over .006 is getting to be to much, IMHO. I hear that S&W now accepts some what larger gaps.

.006" is thought to be about the ideal compromise between bullet performance and revolver reliability under repeat fire.

Kuhnhausen suggests that anything beyond .008" begins to compromise performance. .010" is the outer edge of what S&W used to call "in spec"; that's now .012".

 

[steelslaver]

I like .004, but .006 is good and beyond that things go slowly down hill. Seeing how fixing excessive gap is difficult most would leave it alone up to .010 or so. I might not, but then I have a lathe and a mill and like to play with them.

Just got done, putting another barrel on a model 10 (had split cone), milling the frame and adding adjustable sights and fitting another yoke and 357 cylinder for an experiment. Got a piece of barrel coming in the mail that I am going to make a 16 1/2" barreled 45ACP/45LC carbine out of using a 1917 after hunting season is over.

 

[snubbiefan]

Snap caps would be better but lets not get too "green" here. A knowledgeable gun owner should know how to do this with live ammo.....or they don't need to be handling a gun in the first place. The gun has a hammer-block in it (I guess....it's an INA so I don't know).

OP mentioned he had (basically) ZERO BTCG and I make the assumption that when he holds the cylinder forward....it touches the forcing cone. Folks....this ain't right! If this is correct....he has a more serious issue than excessive end-shake. The barrel is set too deep, or the yoke needs refitting.

If one wants a clone that is the closest thing they can get to a Smith....get an older Rossi. If you crack one of those open....looks just like a S&W on the inside and can still be had rather cheaply.

 

[swampjam]

Thanks everyone. The measurements I posted could be incorrect as they were taken about six weeks ago and I didn't write them down. In other words, they are what I remember which isn't very reliable. I'll remeasure the gaps and post the verified results. I ordered a set of shims from Brownell's yesterday. I'll update when I get the shims installed (if they fit).

 

[ErnieDeBord]

Good chance is end-shake, good chance the frame is made of kinda a pot-metal alloy. trade the thing off and get a S&W. Regards Ernie

 

[steelslaver]

Snap caps would be better but lets not get too "green" here. A knowledgeable gun owner should know how to do this with live ammo.....or they don't need to be handling a gun in the first place. The gun has a hammer-block in it (I guess....it's an INA so I don't know).

OP mentioned he had (basically) ZERO BTCG and I make the assumption that when he holds the cylinder forward....it touches the forcing cone. Folks....this ain't right! If this is correct....the has a more serious issue than excessive end-shake. The barrel is set too deep, or the yoke needs refitting.

If one wants a clone that is the closest thing they can get to a Smith....get an older Rossi. If you crack one of those open....looks just like a S&W on the inside and can still be had rather cheaply.

I have a old Rossi 22 and you are correct about them being very very close to a Smith.

On the other I beg to differ. End shake shims will hold the cylinder to the rear in its correct position and give him his gap. The cylinder should not move back and forth over .002. The cylinder held all the way to the rear he should still have some clearance between the cartridge heads and the recoil shield.

If the cylinder has clearances from .0 to .012 with it held back he has a very out of square cylinder face and moving the rear of the barrel forward .04 for clearance on the .0 holes would make the gap on the .012 holes to .016. Not good. The fix then would be to square up the front of the cylinder in a lathe.

My Model 25 had some end shake with the cylinder pressed forward it had .001 to.002 clearance. with it pressed back about .006-.007. Adding 2 .002 shims gives it a .005 average clearance. Some end shake is not all that uncommon. .012 end shake is a lot though.

 

[shouldazagged]

f one wants a clone that is the closest thing they can get to a Smith....get an older Rossi. If you crack one of those open....looks just like a S&W on the inside and can still be had rather cheaply.

About sixteen years ago, at a time when I wanted a J-frame but couldn't afford a Smith, I paid something like $178 for a new Rossi M88. Almost an exact clone of an M60, though not its equal in fit and finish. Had the hammer bobbed and the trigger face smoothed and radiused, and carried it for a couple of years. Perfectly decent little revolver that performed just fine till I could buy a 640.

 

[snubbiefan]

I completely agree that shims will hold the cylinder off the forcing cone, but I also suggest (again) that even with wear (or due to sloppy manufacturing) the cylinder should never be able to be pushed to the front enough for it to "touch" the forcing cone. It sounds to me like the yoke is not properly machined and is not going "deep enough" into the frame to hold the front of the cylinder off the barrel. It's hard for me to explain, but if you have ever tried to swap-around cylinders on guns....the yokes can vary. I have had this condition with the cylinder touching the barrel to the extent that it would not latch.The remedy is to grab another yoke and try it until you find one that works. That's why Smith does not sell you a cylinder or a yoke....they are suppose to be factory-fitted. Yep....much of the time you can do a simple cylinder swap within frame types, but not always. Sometime, you have a cylinder that won't close or at least an almost zero BTCG.

But...I agree in this case that shims may fix the problem....unless the shims push the cylinder to far to the rear and cause binding due to case-dragging on the recoil shield. It's worth a try.

 

[steelslaver]

If the cylinder is correct it should only move to the rear enough to alaw the correct head space and no farther. When I fit another for a S&W I always get a yoke that way I can fit them together. I have had yoke that held the cylinder to far back to close. Then you need to remove material from the back of the yoke tube. I did this by making a square file guide that went over the tube. To far forward and the shims go on the end of the yoke tube making it longer.

I still have my Rossi 22 and it is just like a J frame. I should have it hard chromed or something and keep it in my jetboat.

 

[snubbiefan]

J-frames have simply gone over the top in price like most others. Just last year, you could buy a Jay for $325-$375 and sell it for $400-$475....most of the time. I realize there are (and can still be) exceptions, but the point is....the older S&W no-locks have gone up....if you can find one.

This is beginning to sound like a Rossi forum, but I hope nobody sees it that way. When you can purchase two Rossi 88's for the price of one Smith Jay....it's a no-brainer. Everybody needs the gun that you could throw away, lose or turn-over to the authorities if the "bad thing" happened and you actually had to use it. The older Rossi fits that bill for me. I have many Smiths and love them all, but my daily carry is a Rossi M88-2 and it's as close to having a model 60 as you can get to actually having a S&W model 60 at less than 1/2 the price.

I have a relative that has a gun being held in the evidence room at a nearby city police department. It was stolen from him and used in a crime. It's been there for going on 5-years now. They keep telling him the case is still under appeal. He and us all know that he will never get that gun back. I had one that was used in a suicide (sadly) and I like to have never gotten the gun back. When I did....the case number and other verbiage was scribed across the side with a hand engraving tool.

My trusted and loved Smith's will stay in the safe, or be shot as I please in a recreational nature. I'll carry my less expensive guns for purpose.

 

[Hapworth]

Snap caps would be better but lets not get too "green" here. A knowledgeable gun owner should know how to do this with live ammo.....or they don't need to be handling a gun in the first place. The gun has a hammer-block in it (I guess....it's an INA so I don't know).

Every qualified gunsmith I've known or heard of wouldn't allow live ammo on a work bench -- some not even in the shop -- much less in the gun actively being worked on.

But my original question was about measuring b/c gap with snaps or shells in the cylinder; that's not common practice, far as I know -- where are you getting it?

 

[Pisgah]

If this gun is like the "Tiger" I have seen, it is not a S&W clone but a very crude copy of a Colt Detective Special. A small matter, perhaps, but perhaps pertinent in trying to straighten things out if true. The one I saw was all-steel, but with very crudely cast parts, poorly finished and fitted. I recall thinking, "It's inexpensive, but at the price I would look for a used S&W, even if it were a rough-looking police trade-in, or else a decent used Rossi."

 

[snubbiefan]

Okay already....use snap-caps, or fired brass if it makes you comfortable. I would never leave live ammo around on a table in which others may have access to either. I fully appreciate and understand that.

I believe if you "read around" here on the forum and other places, you will find that most others say that the gun should be loaded (snap-caps or empties if desired). It may very well depend on the gun, but if you do not have the rims exposed to butt-up against the recoil shield you can arrive at an erroneous reading. Likely...MOST of the time this would not matter in a quality gun as the cylinder (ratchet) should come into contact with the recoil shield before the case rim does.....but that's not always the case. I have owned and fixed cheaper revolvers that had issues with the cases dragging against the shield. Obviously....the cylinder is not touching the shield before the rim of the case does. If you perform an end-shake measurement with an empty cylinder, you're just assuming the rim of the cartridge is riding just below or even with the face of the ratchet. This IS NOT always the case....especially in a cheap gun. There are published ammo specifications.....but rim thickness can vary. I've measured them....I know they do. A new Taurus is notorious for having case-dragging issues. I've fixed too many of them not to know.

 

[Tired Gunsmith]

We always had "dummy" cartidges in our shop to use to check repairs in a 'loaded' condition.

 

[swampjam]

FYI, I remeasured the gaps. With the cylinder pulled rearward, the gap measured .011. At rest the gap measured about .003. I say about because the smallest feeler gauge I have is a .004 and it would go in but very tightly. With the cylinder forced forward I couldn't get anything in the gap nor could I see light. It appears to be up against the barrel.

I have not yet received the shims from Brownell's so have nothing to report regarding them.

I have tried to post a photo of the INA Tiger revolver. I hope it works.

 

[swampjam]

INA Tiger 38 Spc



Here is the picture. Maybe this will work.