MIM Parts and trigger break in

[wcwhitey]

Question? I was always told regarding S&W revolvers that Stainless Steel revolvers always got smoother faster than Blue Hardened Steel guns of the same type. I have experienced this myself as my all SS guns were easier to get smooth from use and dry firing. What about S&W products now with MIM parts, they seem to take more to get smooth. I would have thought that the powdered metal would smooth out easier. In the case of my 629 the trigger still feels gritty after many hours of shooting and dry firing. It has gotten a bit smoother but not silky at all. Might be the N frame and the physics of moving the increased mass. Still feels okay but just not as good as what I would have expected. Lock Maybe?

 

[Mr. Mosin]

Question? I was always told regarding S&W revolvers that Stainless Steel revolvers always got smoother faster than Blue Hardened Steel guns of the same type. I have experienced this myself as my all SS guns were easier to get smooth from use and dry firing. What about S&W products now with MIM parts, they seem to take more to get smooth. I would have thought that the powdered metal would smooth out easier. In the case of my 629 the trigger still feels gritty after many hours of shooting and dry firing. It has gotten a bit smoother but not silky at all. Might be the N frame and the physics of moving the increased mass. Still feels okay but just not as good as what I would have expected. Lock Maybe?

Lock has nothing to do with trigger or hammer travel, or interfacing surfaces; if memory serves me.

 

[wcwhitey]

Lock has nothing to do with trigger or hammer travel, or interfacing surfaces; if memory serves me.

The single action is fine, it’s at the end of the stack that I feel the most grit. Lock Up and function is perfect.

 

[Mr. Mosin]

Not lock up, the internal lock

 

[Pat Riot]

Not lock up, the internal lock

The lock does nothing in regards to the action or the feel of the action.

Now, as to the OP, I have purchased 3 S&Ws with MIM parts versus 5 older configuration revolvers. 2 of those 5 were fired quite a bit before I bought them and were smooth. The other 3, a model 10, 36 & 442 smoothed out over time. The MIM guns seemed to take a little longer but truthfully they weren’t all that bad. The model 25-15 I purchased last year has smoothed out but the DA trigger pull is still heavy. I need to shoot it more to help it along.

I can just go by my perceptions on this as I never measured the trigger pulls on any of them. I am not sure if this is helpful to you.

 

[Col. Harrumph]

I wonder if the stacking is due to compressing the trigger return coil spring. The MR73's action appears to be a direct copy of the S&W except the trigger return, supposedly due to stacking.

 

[Old_Grouch]

The mating surfaces on the MIM parts are rougher. It takes me probably 20 minutes longer to smooth the action on one with MIM parts.
As to stainless steel vs blued break-in, I've been a S&W shooter and enthusiast for nearly 50 years and I've never heard that; nor can I think of a basis for it. S&W SS revolvers don't have SS hammers and triggers They tried that with the early Model 60s (and possibly 66?) but galling was a problem. They stuck with carbon steel and flash chromed (their term) the ones for the SS guns so they would look like stainless.The star on the older SS was stainless, but the hand is not so there were no issues there.

 

[wcwhitey]

The mating surfaces on the MIM parts are rougher. It takes me probably 20 minutes longer to smooth the action on one with MIM parts.
As to stainless steel vs blued break-in, I've been a S&W shooter and enthusiast for nearly 50 years and I've never heard that; nor can I think of a basis for it. S&W SS revolvers don't have SS hammers and triggers They tried that with the early Model 60s (and possibly 66?) but galling was a problem. They stuck with carbon steel and flash chromed (their term) the ones for the SS guns so they would look like stainless.The star on the older SS was stainless, but the hand is not so there were no issues there.

Thanks, I will just keep working them. As far as the SS vs. Blue my point of reference is a Model 66 no dash. I remember when it was purchased it was touted as eventually having a better trigger quicker vs. the Model 19. So it maybe just gun store lore that stuck in my brain.

 

[Old_Grouch]

Model 66 no dash. I remember when it was purchased it was touted as eventually having a better trigger quicker vs. the Model 19.

As I referenced above I'm not sure whether the early 66s had SS parts or not. One of the ways to eliminate galling of SS on SS is to harden the mating parts to different hardness so I suppose if they had used SS internals and not hardened, for example, the trigger to the same hardness as the hammer (or vise versa) the softer part would wear more quickly resulting in a smoother action sooner. That's just speculation, however.

 

[sparkyv]

I've acquired a handful of SS S&W revolvers over the past 3 years. All smoothed out fairly quickly including mt M629. Other than the "HH" locks, I don't understand the "MIM sux" comments (not you, wcwhitey). They are just so sweet! And yes I do own one and have shot many pre-1987 S&W revolvers.

Maybe stoning the rebound slide surfaces will help, wcwhitey...and a lighter (11#) rebound slide spring. It made my already nice triggers extra sweet.

 

[Ru4real]

…products now with MIM parts, they seem to take more to get smooth…

Depends on 1 the MIM process used (powder or liquid) and 2 the quality of the mold.

Fine finishes (super smooth) can be achieved straight out of a high quality mold using the liquid metal injection process with the resulting part being harder, stronger, more ductile, less brittle and more tough than a comparable loss machined part (traditional machining).

Take apart a new Kimber revolver and it’s pretty impressive to see what they have achieved. One of the reasons the triggers are so smooth right out of the box is that Kimber designed reliefs and contact pads into the MIM moving parts specifically to reduce friction.

I bought this 586 and this Kimber within a month of each other. Completely disassembled and smoothed out both guns before I fired them. About 3 hours work on the 586 (sanding, lap, polish) and a half hour work on the Kimber (lapping and polish). The worked Smith trigger is better than the worked Kimber trigger, credit to S&W design.

The fastest and easiest way to smooth a trigger is disassemble, apply small (tiny, not much, very little) amount of 600 grit lapping compound in trigger movement, reassemble, dry fire 100 times, disassemble, clean, reassemble.

Smooth as glass!

 

[ThomasT]

If you want your gun to operate smoothly then do what a gunsmith would do. Take it apart and smooth all the contact surfaces and then lube the gun. Your gunsmith is not going to sit around and click, click, click your gun to make it smoother or wear in the parts.

If you are trying to make your gun feel smooth like a S&W from 75 years ago then do what the factory did back then. They hand fitted the parts. They had to because they weren't as close as todays parts that will drop in and give a serviceable gun without a lot of hand work. Thats why the old guns were smooth. People back then didn't shoot like we do today. Their guns aren't smooth because they shot a 100,000 rounds through them. They were smooth right out of the box.

I have my dads model 28 he bought in the early 1980s for $230 from the police supply house. His brother was a cop and got it for him with a police discount. And that gun is slick as butter. And its slick because S&W made it that way, not because my dad shot the hell out of it. The gun has never been fired. He brought it home, loaded it and put it in his night stand. He died in 2003. I then got the gun. I have never fired it. You will spend a little time getting a new gun to feel like this gun feels.

Do it right and polish the parts. If you don't know how then take it to a real gunsmith and let them do it and stop dry firing your gun.

 

[4v50 Gary]

Was talking to another gunsmith about this very subject. You can only work so much on a MIM metal surface. Results can be great until the case hardened surface wears out and then the part begins to deteriorate. I do not want to work on a modern revover with MIM parts.

The very old S&W revolvers had a tear drop shaped sear which was similar to that of the Colt's. The ones I grew up around in the '80s had the blocky sear that could be smoothened. Oh for the old days.

 

[Old_Grouch]

The ones I grew up around in the '80s had the blocky sear that could be smoothened. Oh for the old days.

The 70s and 80s were generally easy. In nearly all cases crocus cloth was all that was needed. Rarely did I ever need any sort of stone.

 

[Oldschool shooter]

I have 2 J-frames. A model 36 from the late 70s, and a current model 638. The model 36 had a smooth trigger pull, albeit heavy. I did some light polishing and changed springs. Smooth as glass with 8 1/2 lb double action pull. The 638 got the same treatment, now has a 9 1/2 lb DA trigger pull. Not quite as smooth as the 36, but better than it was. Could just be due to having shot the 36 more and for a longer time.