S&W Revolver Dis-assembly - Model 66

[alfsauve]

I'm pretty good with mechanical things.  I know the value of using the right tool and right jig to hold parts during assembly/dis-assembly.   But it never hurts to hear from those who've done it.

As some may know, I've a newly acquired Model 66 (no-dash ----  pre 1977) and the hammer strike is too light to reliably fire rounds.  So,

No problem in removing side plate, main spring (hammer spring) and hammer.  From the parts list the hammer nose (firing pin) did NOT have a spring on any model before the -3.  It should be and is loose.   I don't see anything that is blocking the hammer from making the full "fall" and the rebound block and hammer block (I call it a "key") all seem to be in place and functioning.   The Strain Screw on the main spring was already tight so that's not the problem.    I may while waiting on parts try straightening the main spring a little.

Parts aren't too expensive, so I thought I replace the hammer nose and main spring.

HERE'S THE QUESTION.   

How does one remove the Hammer Nose Rivet?   It's a "rivet" not a "pin".   I don't think it's suppose to be "punched" out.   My guess is I need to make a jig to clamp the hammer in a press and then drill it out as one would do any rivet.    The only other Smith I've removed the hammer nose was a drift pin style not a rivet.

[kmitch200]

Tweak (bend) the mainspring a bit. That should give you enough thump on the primer.
I wouldn't worry about the hammer nose rivet if you don't have to.
My old 1917 45 doesn't have a spring and the hammer nose flops around. It's no biggie.

It's *maybe* possible that someone ground off a bit of the strain screw, (dumb) but it's more likely that the spring had some bend added to it to lighten the pull, since that only takes about 3 seconds.

Add some tension to the mainspring and try a primer. If you change the rivet, you could end up with what you already have.

[m25operator]

Does the action feel light? I would start with the mainspring, I have run across shortened strain screws in the past and a quick fix is to take a spent primer, remove the anvil and place the primer cup on the end of the strain screw, if it works you have probably found the culprit.

As to the hammer nose, before I got my Powers jig, ( which I love ) I would just use my bench block that I drilled several different size holes in, take a small short, 1/16" punch, place the rivet over a hole and punch it through, I have reused the rivets, place back in the hole and use a 1/8" roll pin punch to restake it, they say never do it, I have several times, but I do keep them and mainsprings, screws etc.. in stock now.

[ellis4538]

I agree w/m25...Take the strain screw complete out and check to see if it has been filed down.  Common wisdom way back when said instead of screwing the screw out a bit just file it down some and Loc-tite it in place fully screwed in.  I have never heard of one lightened too much to let off factory ammo!  If you are using reloads you might need to get Federal primers and make sure they are fully seated (read below flush!).

FWIW


Richard

PS:  Check to see if the FP tip isn't broken and filed round again.

[alfsauve]

Thanks for the tip M25.  By all I can tell the hammer nose looks unmodified or damaged.  I thought I might swap it out with another K/L frame one and see if it made  a difference.   But it's too much trouble.  Yeah the old M&P is floppy, but the 586, 686 and 624 all have springs.  The parts list shows they started using a hammer nose spring with the -3 in 1986

I didn't look for modification to the strain screw, but I'll go back and do that.  It wasn't loose, but thanks for the tips on using a primer cup.   The mainspring did look like it had been bent, so I gently did some straightening.  The action seem a little stiffer now.   I just happen to have a bunch of primed cases that I'm going to give a try when the company all leaves..... 

[Sponsor]

[alfsauve]

Removed and examined the hammer spring.   There was a definite "bend" and a mark on it, as though someone had clamped it in a vice with out any protective pads.    I put it in my vice (with pads) and gently straightened it.

Re-installed and ran 30 primed shells through it.  All fired, double action.   Do note these were magnum primers not standards.  The gun may have fired okay with standard primers, but that's not what I use in my .357 loads.

So, I've ordered a new mainspring from Brownells which should be here this weekend.  Once I accumulate some cash I'll put original grips on it.   More next week after a full range workout.

[alfsauve]

Got the hammer spring today and installed it.  My dad's visiting (age 91) so this killed some time sitting around the kitchen table.

Ah, the new spring is so stiff that I had to back off the strain screw some, else the rebound spring couldn't reset the hammer.  Haven't tested it with primers yet.   I may have a small window tomorrow to do that.   Unfortunately, I have to work from 2pm until midnight.  One the busier days in the church biz.   All the Chris-Easters who only show up two services a year.

[badbob38]

Hold the two together and if the the same,that  spring should be tigh if loose you will lose it after shooting a box or two you will lose that screw. something funny going on.  i think you have the wrong spring.

[alfsauve]

Hold the two together and if the the same,that  spring should be tigh if loose you will lose it after shooting a box or two you will lose that screw. something funny going on.  i think you have the wrong spring.

Oh no,  identical springs.  Just the new one hasn't been bent out of shape like the old one, which showed marks where they clamped it in a vice and bent it.

Only took 3/4 turn off the strain screw and it functions flawlessly.  The hammer spring isn't loose by any stretch of the imagination.   This is the way it's suppose to work, you use the strain screw to achieve the proper tension and still allow for trigger reset.   Over time as the spring looses temper, I'll have to tighten it some.   

Did 50 rounds of .38spl target and 100 rounds of full power .357 mag.  Works like a champ.