Trigger: Model 39 vs 52

[Tom S.]

I know I'll never be able to approach my 52 for trigger pull, but 7lbs on the SA pull is not conducive to good groups. I can do a 1911 blindfolded, and have lightened up the trigger in Mr. Browning's other design, the High Power, but I'm inexperienced with the 39 and would appreciate any tips you can provide. If I can get it to 4lbs, I'd be pretty happy, and if I could get it to 3 or even 3.5, I'd be thrilled.

One last question: will a 52 trigger fit and function in a 39? I'm thinking probably not, but that wide, smooth faced trigger would sure be nice.

Thanks in advance!

 

[WR Moore]

I've never compared the sears and hammer hooks of both, no idea if they'd interchange. Frankly I doubt it. A try of the 52 hammer might be interesting.

Light stoning of the sear surface that mates with the hammer will help. As will adjustment of the tension of the sear spring. That's the flat spring in the frame. A spring kit with a reduced power mainspring and polishing of the inside of the mainspring cup will help.

Factory spec for the SA pull on the S&W service autos is 4.5 lbs minimum. I personally wouldn't drop below factory specs. I find too much a difference between DA and SA pulls to screw up my transitions between the two modes. Allthough that doesn't seem to be your usage..

 

[Tom S.]

WR Moore - your assumption is correct, this will never be a carry gun, just a paper hole puncher. It's something I found at a LGS and have been playing with for fun. Since it looks like I'll never be able to find the parts to convert my 52 to 9mm, nor be able to afford the prices 952's are bringing, I just wanted to play around with this 639 to see what could be done. Thanks for the suggestions.

 

[Jebus35745]

I've often wondered if an aftermarket 9mm barrel installed would help the accuracy of a 39 and make it a better shooter. It would be nice to have a very accurate 39 on par with the 952. Larry

 

[Tom S.]

I've often wondered if an aftermarket 9mm barrel installed would help the accuracy of a 39 and make it a better shooter. It would be nice to have a very accurate 39 on par with the 952. Larry

An easier fix might be a bushing that could be fitted.

 

[armorer951]

I have worked some (ongoing) on my old, "police trade in" 5906. Ater making a fixture/jig to hold the sear, cleaning up the milling marks, SA hooks, etc on the hammer (forged), changing the hammer spring, and doing some other minor modifications, the gun now has a 4 pound SA trigger pull. A trigger stop would be nice, but haven't had time to work on one, and I'm not sure the disconnect will have room to work properly with an OT stop installed.

A lot of work on an M&P design trigger, especially when the accuracy is just average.....and there are the monumental trigger take-up and overtravel issues. It's a fun challenge but I'm not sure it's capable of better than 4lbs without compromising reliability. It's a range gun, so reliability is not a big deal.


Sear fixture:




bottom has small adj screw:

 

[M29since14]

An easier fix might be a bushing that could be fitted.

Well, a junky barrel isn't going to provide match results with just a tight bushing. I don't know if you can use it as a guide with the 39 but it seems a lot of 1911 builders think bushing fit only accounts for 10-20% of an "accuracy job," and that presumes that the barrel is of good quality to start with.

I too would like to have a good shooting 39, but that project has eluded me. I haven't done much but tinker with springs and handloads, but I think the chances for success with the factory barrel may not be great, unless you get a particularly good one - but who knows? Does Bar-sto, or anyone else, make aftermarket barrels for the 39?

 

[Tom S.]

Well, a junky barrel isn't going to provide match results with just a tight bushing. I don't know if you can use it as a guide with the 39 but it seems a lot of 1911 builders think bushing fit only accounts for 10-20% of an "accuracy job," and that presumes that the barrel is of good quality to start with.

I too would like to have a good shooting 39, but that project has eluded me. I haven't done much but tinker with springs and handloads, but I think the chances for success with the factory barrel may not be great, unless you get a particularly good one - but who knows? Does Bar-sto, or anyone else, make aftermarket barrels for the 39?

I know for a fact that Bar-sto does not because I asked them about 5 or 6 weeks ago. I'm not sure about anyone else though. I'm not ready to write the barrel off as being junk however. One of the keys to getting an accurate semi auto is to get the barrel to return to battery in the exact same spot, shot after shot. If my geometry serves me right, the difference of just .001 will result in a shift of .25" at twenty five yards. Going with an oversized barrel lets you fit the barrel to the stock bushing for a tight fit, but that still leaves potential movement in the bushing itself, which is why I wanted to try an oversize bushing, if there is such an animal.

Of course I could forgo all of this if S&W would reintroduce the 952.

 

[WR Moore]

Don't write the factory barrel off. My personal 5906 will shoot one ragged hole at 25 yards from braced sitting with good ammo. Yes, I worked the trigger and did a couple things I didn't mention above BTW, when you work the sear, don't forget the relief cut, ala 1911), but kept the SA around 5 lbs (and maybe a bit more) cause it was my off-duty piece.

Glad to see I'm not the only one who's made a sear jig for the S&W autos. Going to a 5906 type bushing and barrel might help the accuracy on the 39. You'd also have to go to the same type of recoil spring guide. The barrel you could get from Smith, the bushing would be a custom job. Ah, see yours is a 639. That helps somewhat.

There's several ways to fit OT stops. On DAO S&Ws I drilled the trigger and installed the stop there. On MIM triggers an end mill works best for the hole. Might also be possible to drill the frame for an OT stop, never really considered that. I do believe the 52 has a stop installed at the factory. Where exactly did they put that?

I really wanted one of the PPC versions of the double column 9mm Smith made for a bit. Couldn't find one-at least at a price I was willing to pay.

 

[Tom S.]

WR, the over travel screw on the Model 52 is frame mounted. There's no additional material there, just a drilled and tapped hole with a set screw.

 

[WR Moore]

Thanks Tom,

After looking at the skematic, it would seem the 52 trigger might fit the 39 frame, but I'd have to compare a lot of parts numbers to see what all might be necessary to do the transplant. The 52 trigger appears to have a significant ledge on it to bear on the overtravel screw. Probably more trouble than it's worth.

FWIW, you didn't mention any accuracy issues, but looking at the parts lists, the 639 appears to have a unique barrel and barrel bushing. Replacing them with the appropriate 5906 parts might tighten things up a bit. Having said that, replacing the bushing ain't a kitchen table operation.

 

[shovelwrench]

I have a 539 that I scratch-made a barrel bushing for in attempts to improve accuracy. And it did!!

My barrel has a slight taper down the whole length, it was fairly easy to make a bushing that locks the muzzle perfectly when in battery.

I've been tossing around the idea of sending this pistol in for a single action conversion for quite some time, just haven't pulled the trigger!!

A parts list to convert it myself would be great!! I guess I should start looking at schematics and available parts.