Trigger job help!

[kmc]

I was recently bitten by the d*mned revo bug and got myself a 625 4" gun. I shot it new out of the box in a match and quickly decided the trigger needed some serious help. I've just completed my first trigger job but I'm having inconsistency issues.

My "trigger job" consisted of swapping out the springs for a Miculek set of springs, bobbing the hammer spur, removing the lock, installing a (long) hogue cylinder release, installing an extended firing pin, and polishing via Miculek's Trigger Job DVD. I was conservative in bobbing the hammer spur, taking off the spur and a curved edge that left the hammer contour similar to the lines of the frame. I followed the Miculek DVD carefully, making sure I wasn't too aggressive. I disassembled the lock and just removed it, leaving an empty hole. I swapped out the firing pin for the extended pin and I left the hammer block in the gun. After installing the springs, I adjusted the screw until I had about 7lbs on the pull. The trigger certainly feels substantially better, both smoother and lighter. The only thing I thought strange was the "return" spring in the Miculek kit was quite a bit longer than my factory spring (though it was thinner and further between coils). I then loaded some rounds with Federal primers making careful to get a full seat and then gave it a go.

Unfortunately, not all rounds would fire. The primers for the fired rounds were hit squarely in the center. The primers on the rounds that did not fire seemed to be unmarked or even nicked at the end of the primer, but not dead center. I tried several things to resolve the problem: I adjusted the spring screw until it was all the way in, I tried pulling the hammer block out, I swapped back to the factory firing pin, I swapped the seemingly very long "return" spring for the shorter factory spring (leaving in the Miculek hammer spring, and I hand-primed a set of rounds. Unfortunately, none of these alterations worked...I still can't fire more than 4-5 rounds per moon clip. If I do keep pulling the trigger, eventually they will fire successfully.

I'm looking for ideas...any idea on what might be wrong? what should I try next?

[Toolguy]

First - make sure all your primers are well seated. Second - check to see that the bottom of the hammer isn't contacting the rebound slide with the trigger all the way back. There should be a little clearance where if you hold the hammer all the way down against the frame, the trigger and rebound slide should be able to move front to back a little. If the hammer is hitting the rebound slide, it takes away from the energy transferred to the primer. If it is hitting, radius the corners where the parts contact to create a small clearance. Once that is satisfactory, put back the original mainspring and the new rebound spring and see what you get. You can hook a spring type trigger pull gage under the ledge on the hammer to check mainspring tension. You will need 50 to 60 ounces of pull on the gage for reliable ignition. The weight varies because of gun to gun differences.

Edited November 20, 2011 by Toolguy

[R112mercer]

The primers on the rounds that did not fire seemed to be unmarked or even nicked at the end of the primer, but not dead center.

I'm no expert, and I didn't stay in a Holiday Inn Express last night, but I would look to your cylinder stop & timing. You said the gun was NIB, but that doesn't mean it didn't leave the factory screwed up, it happens. Make sure the gun carries up and stops with the cylinder stop in the notch. Usually the stops are OK, but they do go bad. Check all the cylinder notches to make sure they're not peened. It could also be the timing in the star, which is a pain to fix. I'm assuming when you test fired you shot slow speed, if you didn't, go fast on dry fire and see if the cylinder over spins. If so it's the stop, buy a new one & just swap it in.

[Waltermitty]

http://www.brianenos.com/forums/index.php?showtopic=114185&st=0&p=1296275&fromsearch=1entry1296275

You'll also need to check end shake for clearance.

Loosening the strain screw will not be reliable. There are other discussion threads on shortening the strain screw, which has been my best success.

So, center up all moving components. Hammer and trigger. Shim to reduce play. Smooth everything out.

You have a reduced spring set. Stick with that for now.

Once that other work was done. I ground down my strain screw. That's another post.

After you've got 100% reliability, start backing off return spring force to reduce trigger pull.

[snertley]

I think we got it figured out. I believe it was Kevins goobered up cylender stop spring sticking just long enough to allow Skip to visit and result in an edge hit on the primer/brass. Swapped out his spring for one out of my gun and seems to have taken care of the problem. He is ordering some new springs and we will see if it takes care of the problem.

[kmc]

Thanks for the comments and suggestions. I should have pointed out that I shot it straight out of the box for ~500-600 rounds without a single failure before I dug into this trigger job. I'd had it for all of 60 hrs when I shot it at the Memphis Charity Challenge...quite the baptism into shooting revo. I tried some of the suggestions above but couldn't find anything wrong. A buddy stopped over and we started swapping parts. I had kinked the cylinder stop spring when initially removing it. After swapping in his stop spring and getting it placed properly, we seem to have made the problem disappear. I think the problem must be that spring was binding and not locking up occasionally, causing "timing" issues. I've got a new set of springs on the way now. We'll see if that actually solves the problem...

[RePete]

When having these types of problems, I aways put the gun back to the way it came from the factory and re shoot.

I had problems when I stalled the Miculek springs. I ended up removing them, installing a Wolffe 14lb rebound spring (I've also cut 1 1/2 coils from the factory spring without issue) and left the factory mainspring in it. I will, sometimes, use a Wolffe Power Rib Spring too.

[kmc]

Yes, that's a good idea. Unfortunately when I put it back to factory springs, it exhibited the same problem. Which led me to start swapping parts...which led to finding the binding cylinder stop spring.

[dauntedfuture]

How light can you go with the trigger return spring? I cant see how it could be too light, or i just dont fully understand what it does other than return the trigger forward.

[kmc]

From what I've read, the key is to have the return spring matched to the hammer spring. I just installed the matched set in the Miculek spring set. That said (as stated by others), I'm no revo expert and I did not stay at a Holiday Inn Express Express last night.

[Toolguy]

The trigger return spring (and rebound slide) also rebounds (lifts) the hammer up off the frame after firing. Because of that, a heavier hammer spring requires a heavier rebound spring.

Edited November 23, 2011 by Toolguy

[RePete]

Does the gun have a frame mounted firing pin or is it in the hammer nose?

[Carmoney]

As several others have indicated, the springs should be balanced to one another. There is no spring kit that reliably accomplishes that. Too many small variables from gun to gun.

[kmc]

My particular gun is newer 625-8 and has a frame-mounted firing pin.

@carmoney - is there any technique that "a commoner" might follow to get the right balance for a particular gun?

[dauntedfuture]

For what its worth i polished the sides of my hammer, trigger, hammer return spring keeper and hammer block bar. I think it helped as i noticed some wear marks on the sides of the hammer. Might have been a waste of time and I would defer to the experts.

[D.carden]

I'll see if i can help......

Proper ignition only depends on the hammer fall weight, and nothing else. You need to set that first.

Using a bent Q-tip to capture the hammer and release it from the trigger completely..

Photo-1: begin trigger pull

Photo-2: install Q-tip and capture hammer after full trigger pull.

Photo-3: hammer is captured with trigger to full rear position and hammer fully independent of trigger (free floating)

Photo-4: check main/hammer spring weight with gauge. At this point, you should have about 2-lbs at the approx release point where the trigger lets go...

My 625 and 627 are 100% reliable at 1-lb 12-oz. Of course, Federal primers

As far as TOTAL combined weight goes, hammer and rebound, this is where you tune to your liking. I prefer a snappy/heavy rebound, so I use a stock rebound with a few coils cut off. After market parts/polishing/wear will all have an effect on actual weights. But keep in mind, that the ignition part is always on the hammer drop...That setting should never change once your 100%.....!!!!

Dan...

Edited November 23, 2011 by D.carden

[Waltermitty]

I'll see if i can help......

Proper ignition only depends on the hammer fall weight, and nothing else. You need to set that first.

Using a bent Q-tip to capture the hammer and release it from the trigger completely..

Photo-1: begin trigger pull

Photo-2: install Q-tip and capture hammer after full trigger pull.

Photo-3: hammer is captured with trigger to full rear position and hammer fully independent of trigger (free floating)

Photo-4: check main/hammer spring weight with gauge. At this point, you should have about 2-lbs at the approx release point where the trigger lets go...

My 625 and 627 are 100% reliable at 1-lb 12-oz. Of course, Federal primers

As far as TOTAL combined weight goes, hammer and rebound, this is where you tune to your liking. I prefer a snappy/heavy rebound, so I use a stock rebound with a few coils cut off. After market parts/polishing/wear will all have an effect on actual weights. But keep in mind, that the ignition part is always on the hammer drop...That setting should never change once your 100%.....!!!!

Dan...

Nice post Brother Dan!

[4mike]

failure can be caused by the protrusion milling

(In the field of red mark on the picture)

to indicate the friction recommend blueing hammer

[kmc]

Thanks for everyone's suggestions. In the end, I changed out the (tweaked) cylinder lock spring and now the timing is dead on and I've got a trigger weight of just under 6.5lbs. I suspect I might be able to go lighter yet but I like the smoothness and its waaaaaaaay better than before.

I'll upload pics here if I can figure out how. I'm told that I could get MUCH more aggressive on my spur removal but hey, this is a first crack!

[Shadowrider]

You did the same thing I did. I was nervous about going crazy on the hammer on my 625 too. Shot it like that for awhile and realized it needed alot more. So I whacked off the whole "tail end", just continuing the line you have all the way down towards the hammer pin hole. I don't remember the exact numbers, but I think I reduced the weight of the hammer by 46% from the factory weight.

[kmc]

You did the same thing I did. I was nervous about going crazy on the hammer on my 625 too. Shot it like that for awhile and realized it needed alot more. So I whacked off the whole "tail end", just continuing the line you have all the way down towards the hammer pin hole. I don't remember the exact numbers, but I think I reduced the weight of the hammer by 46% from the factory weight.

So essentially a straight vertical from the where I started cutting? A buddy told me there is a molding line you usually follow but I didn't feel good going deeper than this to start. Maybe I'll get my dremel back out...

[Shadowrider]

You did the same thing I did. I was nervous about going crazy on the hammer on my 625 too. Shot it like that for awhile and realized it needed alot more. So I whacked off the whole "tail end", just continuing the line you have all the way down towards the hammer pin hole. I don't remember the exact numbers, but I think I reduced the weight of the hammer by 46% from the factory weight.

So essentially a straight vertical from the where I started cutting? A buddy told me there is a molding line you usually follow but I didn't feel good going deeper than this to start. Maybe I'll get my dremel back out...

Pretty much. What I mean is basically draw a line from the very top of the hammer all the way down past the pin hole. Obviously, you want to "stay off" the pin hole some.

This is what I'm talking about:

My link

[kmc]

Pretty much. What I mean is basically draw a line from the very top of the hammer all the way down past the pin hole. Obviously, you want to "stay off" the pin hole some.

This is what I'm talking about:

My link

Great, thank you. BTW, did you notice any change in your single-action pull? Not that I'll ever use it (and survive the humiliation) but it seems that my single-action trigger requires more movement/effort than prior. I'm not sure if its in my head, a result of the cutting, or a result of some other change I made. I can't see any valid reason why it should have been impacted.

[Shadowrider]

Pretty much. What I mean is basically draw a line from the very top of the hammer all the way down past the pin hole. Obviously, you want to "stay off" the pin hole some.

This is what I'm talking about:

My link

Great, thank you. BTW, did you notice any change in your single-action pull? Not that I'll ever use it (and survive the humiliation) but it seems that my single-action trigger requires more movement/effort than prior. I'm not sure if its in my head, a result of the cutting, or a result of some other change I made. I can't see any valid reason why it should have been impacted.

If you removed the spur of your hammer, you are probably pulling it PAST the SA notch and off the end of the hammer. I never use a bobbed hammer gun in SA.

Edited December 7, 2011 by Shadowrider