Hard to move cylinder latch

[Hair Trigger]

I have a M48-4 that's had a long-standing issue; the cylinder latch is very difficult to move, so you can open the cylinder. Since I'd bought the gun used, I figured it was just gummed up from being over-oiled or under-cleaned. What made it most irritating was getting it closed enough that the hammer would move back.

I finally decided to see what was going on. Off came the stocks and side plate; immediately, the cylinder catch was easy to move. Something was binding, because everything was clean and spotless, no gummed up anything. I took the hammer spring and hammer out, and started looking at the bolt (cylinder catch), since it was what was hard to move. I took it out, and measured its thickness with a micrometer, then measured as best I could, the slot in the frame it fits in. I discovered that the bolt was 0.0025 thicker than the slot it sat in. Doesn't sound like much, but it was enough that, with the side plate on and tightened, there was not enough clearance between the bolt and the side of the hammer, causing it to bind.

I clamped it in a vise, with the edge that meets the hammer up, and took a jeweler's file and filed that side down, then took a Washita stone and honed the file marks down until it was smooth. I took off about 0.003". I replaced the bolt in its slot, replaced the hammer, hammer spring and side plate, and it is now smooth as can be, very easy to open and close with the thumb latch.

I cannot see how this was never an issue for the previous owner, maybe that's why I found this very nice revolver on the used shelf at the LGS a couple of years ago.

 

[chief38]

Parts come out slightly different sizes when hammer forged. They are supposed to become relatively uniform when cleaned up but obviously this one slipped through.

When taking off a small amount of metal as you did (.003") I would not even have used a file. I like to stone the part down since it's final size wasn't all that much thinner. This process takes a little longer however I find it to be more accurate and when the final size is achieved and there is no need to smooth off machining marks. Plus, when laying a piece of metal on top of the stone and moving the metal - it remains perfectly flat and does not distort the shape at all if it's a flat piece. I always use oil too.

Other than that - I am glad to hear you solved your issue. Shoot straight and enjoy the new to you gun.

 

[Hair Trigger]

When taking off a small amount of metal as you did (.003") I would not even have used a file. I like to stone the part down since it's final size wasn't all that much thinner. This process takes a little longer however I find it to be more accurate and when the final size is achieved and there is no need to smooth off machining marks. Plus, when laying a piece of metal on top of the stone and moving the metal - it remains perfectly flat and does not distort the shape at all if it's a flat piece. I always use oil too.

Other than that - I am glad to hear you solved your issue. Shoot straight and enjoy the new to you gun.

I thought about just stoning it until it had clearance, but was lazy and didn't want to take the time. When I clamped the piece in my vise, I had it so the top surface of the vise guided my file, meaning I sacrificed a tiny bit of the vise. This way kept the surface I was working on flat, so I didn't round it over any. I used oil both during the filing and the stoning, I treated it like putting an edge on a blade. It only took a couple of minutes to cut the piece down, another couple of minutes to stone it. I'm guessing the total amount I removed, based on after replacing the bolt in its slot and running my finger over it, I could tell it was slightly thinner than the slot it was in. I wanted just enough off that the hammer did not rub it when assembled. I though about how I wanted/needed to do this before I started, didn't want to screw anything up.

 

[chief38]

I thought about just stoning it until it had clearance, but was lazy and didn't want to take the time. When I clamped the piece in my vise, I had it so the top surface of the vise guided my file, meaning I sacrificed a tiny bit of the vise. This way kept the surface I was working on flat, so I didn't round it over any. I used oil both during the filing and the stoning, I treated it like putting an edge on a blade. It only took a couple of minutes to cut the piece down, another couple of minutes to stone it. I'm guessing the total amount I removed, based on after replacing the bolt in its slot and running my finger over it, I could tell it was slightly thinner than the slot it was in. I wanted just enough of that the hammer did not rub it when assembled. I though about how I wanted/needed to do this before I started, didn't want to screw anything up.

When working on a gun, machine part or anything critical or hard to replace, it's always better to move the work and not the file (if at all possible of course - sometimes it can't be done that way), sand paper or stone. I find by putting a fresh piece of sand paper or emery paper on a piece of glass keeps it flat and true. Then you move the work which should be 100% in contact with the paper or stone.

Stones cut slower than a file but I actually prefer that. It keeps me from going too far. Whenever I work on a gun or a valuable or irreplaceable item, I will not do so when I am tired, in a time crunch or when my wife is talking to me. I do my best work after she's asleep or out shopping - LOL!!!! Stones leave a nice smooth surface that doesn't need to be smoothed out after achieving the correct dimensions.

I might be one of the few here that do it this way, but it's been successful for me and doing it that way I've yet to ruin any parts. A sharp file cuts fast.

Not criticizing your method - many would also use a file, just not my style. I'm not in a rush so I go for the best results. The part you filed is not all that critical and a thousandth or two won't make a difference as long as it works smoothly.

I give you credit fir having the confidence and skill to diagnose and fix the problem - GOOD FOR YA!!