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Old 03-10-2007, 01:25 AM
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Problem - Hammer "follows" slide



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Well, I may have boogered something up. While trying to clean up the trigger (i.e. smooth and lighten the pull) I'm afraid I may have stoned/polished something too much.

My problem is as follows:

1. When fully assembled I pull the slide to the rear and release it...the hammer "follows" the slide home and does not stay cocked.

2. When I remove the slide, I can manually cock the hammer and it stays put....it also has a very nice, light trigger pull.

3. If I rack the slide with the sight rail off, the hammer stays cocked and the trigger functions as normal.

4. If I put the sight rail on, and leave the screws "loose" the hammer will cock and the trigger functions, but is waaayyy too light...I could breath on it and it would trip.

So, did I mess up and do I need to order a new sear/hammer?

Any tips would be much appreciated...I'm enjoying learning how to work on a pistol, but want to be safe!


Thanks,
Chris
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  #2  
Old 03-10-2007, 08:11 AM
LDBennett
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cbecker33:

If you read the following little article and the info is all news to you, then you made the first mistake of home gunsmithing: you took on a task that effects the safety of the gun without understanding how to do the job correctly.

LDBennett

TRIGGER JOBS ON HANDGUNS AND RIFLES:
(Single Action Mechanisms)
By Lynn Bennett

INTRODUCTION

Over the last 20 years I have done trigger jobs (on the single action part of the mechanism) on virtually all my firearms. I read everything I could on each gun and the basic theory of trigger operation in order to do it “right”. But it was not until recently when I bought the American Gunsmithing Institutes (AGI) 8 hour Trigger Job course did I really know how to do a trigger job correctly. I have reviewed the DVD’s repeatedly and put to practice the techniques revealed there with great success, at least in my mind. The process makes a whole lot more sense to me now. If you desire to get educated on trigger jobs this article most certainly will get you started. Of course, the best approach is to buy the AGI course (expensive) and do it your self.

I have no affiliation with AGI or gain no profit from this article. I offer it as simply information and education. Do with the information whatever you wish (I am not responsible for your actions). Trigger jobs can impact the safety of your guns. Be aware and be safe!

TERMS DEFINITIONS

The common terms used to describe the process of setting off a firearm and the maladies of the mechanism center around a few words: Pre-travel, Creep, Over-travel.

Pre-travel of the trigger action can also be called trigger take-up and it refers to the trigger travel that does nothing more than take up the “slop” of the pull before anything really starts to happen to set off the gun. European advanced trigger systems always include pre-travel as do most tactical and military firearms. It allows you to pull on the trigger up to the point where serious resistance is just felt without a surprise firing of the gun. It must be low in force to contrast the higher force required to actually set the gun off. Some triggers are designed and or adjusted to not have any pre-travel or at least a minimum amount. The former is called a double stage trigger while the latter is called a single stage trigger.

Creep is the movement of the trigger, after the pre-travel, against the force of the mechanism just before the gun goes off. Creep can be smooth feeling or gritty or notchy or long or some other feel that puts the shooter off in finding the critical spot where the gun goes off. In general creep is considered to be bad but if it exists and you can not feel it, it probably is not really bad. All guns must have some motion of the trigger (creep) to some degree for the mechanism to work. A good trigger has creep that is not distinguishable or noticeable.

Over-travel is the motion of the trigger after the guns goes off. Some shooters like that travel resistance to be long so that the motion of the trigger is not stopped during setting the gun off (these people are in the minority). The rest like to pull through the pre-travel, load the trigger against the mechanism’s force, and have the trigger to apparently never move at all. As stated earlier the mechanism must move some (have creep) and must move beyond the set-off point to assure that the tolerances don’t all build against the mechanism in inclement weather or conditions. A “perfect” trigger feels like there is pre-travel, a force is applied, the gun goes off, and the trigger never moves past the end of the pre-travel. But it is the apparent feel that counts, not the actual motion. Smooth creep and a small amount of over-travel can usually never be felt. It is said that a perfect trigger “breaks like a glass rod”.

PARTS OF THE TRIGGER SYSTEM

The two main types of trigger systems are hammer type and striker type, as used in rifles. Hammer guns can have the hammer exposed as on Colt 1911’s or hidden as in a S&W Model 41 target gun. The hammer is cocked and the trigger action releases it to fly forward into the firing pin (or as in a Colt Single Action Army Revolver the firing pin is attached to the hammer itself). Striker guns have the striker (usually the spring loaded firing pin) held back initially then released by the action of pulling the trigger.

Hammer guns have a spring loaded hammer whose function is to hit (or be) the firing pin, a trigger that transmit the human force into the system, and the sear in the middle that acts as a link between the hammer and the trigger (Colt Single Action Army and similar guns use no sear but have the trigger operate directly on the hammer-the engagement point is often called the sear surface regardless that there is no actual sear part).

Striker guns can have more than one lever that is used as a sear but the function of the sear (or sear surface) is to act to safely retard the action of the firing pin (striker) until a reasonable force is applied to the trigger.

In the systems are springs: a trigger spring to make the trigger return to its initial position, a sear spring to make the sear return to its initial position and to offer a force to keep it engaged, and a hammer/striker spring to give energy to the mechanism that gets transferred to the primer in the cartridge so that the primer will explode to set off the cartridge.

The trigger system includes linkages between the main components that transfer trigger force and a mechanism to safely operate in a single fire mode (a disconnector mechanism that disconnects the trigger from the sear after the hammer/striker is allowed to fall and that allows the trigger to reset with the release of trigger after the gun goes off). Most guns include a way to keep the gun from being fired unless the slide or bolt is completely closed. It is usually in the trigger linkage between the trigger and the sear.

A trigger job modifies the sear engagement surfaces and can include reduced power springs. The idea is to reduce the pull weight (to a safe level), make the trigger feel creep free, and reduce the over travel of the trigger after the gun goes off (optional feature that most users want). The key is modifying the sear surfaces.

THEORY OF SEAR OPERATION

To keep the discussion simple we will describe the trigger operation of a hammer system that includes a normal separate sear actuated by a trigger. It will be easy later to understand how this applies to a system with added linkages, disconnectors, and other variation of the system. This basic discussion is the key to it all.

The hammer includes a notch into which one end of the rotating sear fits. The other end of the sear is touched by the trigger so that force on the trigger rotates the sear which pulls it out of the notch in the hammer. If the hammer notch and the sear end are angled so that the action of moving the sear out of engagement is a straight pull with no motion of the hammer, the engagement is said to be “zero angle”. This sliding of the sear surface on the hammer notch would be on a radial line through the hammer’s center of rotation (the hammer pin).

If the hammer notch and the sear end are angled so that the action of moving the sear out of engagement is NOT a straight pull but results in a movement that is accelerated by the hammer spring, the engagement is said to be “negative angle”. The line of engagement is NOT a radial line but a slope that the sear easily falls off of. In fact it may not be possible for the sear to stay in the notch at all except for the friction between the sear surface and the hammer notch. This is NOT a safe trigger at all! In fact a zero angle trigger is too close to this situation to be safe, as well. Neither of these configurations should be allowed in modifying any trigger system, as they are both unsafe.


If the hammer notch and the sear end are angled so that the action of moving the sear out of engagement is NOT a straight pull but results in a rearward motion (a cam’ing action) of the hammer, the engagement is said to be “positive angle”. Obviously there are degrees of this condition and we should strive to achieve some degree of positive sear angle for safety, but yet the closer to zero the lighter the pull can be. This is because as the hammer is cam’ed back the trigger mechanism has to work against the hammer main spring which in most guns must be substantial in its resistance to get to adequate levels of energy to set off the primer. In a zero angle engagement only the friction of moving the sear across the hammer’s notch is resisting the trigger pull. But remember that the zero angle sear engagement can become dangerous and make the gun unsafe. So we must have positive sear angles.

Ideally both the sear end and the hammer notch should have the same exact angle of engagement to distribute the force of holding the hammer back across the entire engagement surface. This approach allows the wear to be distributed across the entire engagement surface and not on a pointed surface. But typically this is not done and the angles are not equal. If this is the case neither angle, on the end of the sear or in the hammer notch, can be allowed to be anything but positive. If either is negative the engagement as a whole is negative regardless of the other component’s angle. So the engagement must be treated as a whole to gain a safe trigger.

For striker system the notch is in the trigger and the sear rests in the notch. Pulling the trigger allows the sear to slide out of engagement and release the firing pin/striker. Often times there are several levers in the system but only one sear engagement set of surfaces. This engagement must be positive or an unsafe trigger will result.

There are several elements that control the feel of the trigger besides the geometry of the system. The springs (trigger, sear, hammer/striker), the friction between the sear engagement surfaces, the fit and tolerances of the pins that the components rotate on, and friction between moving parts and their housings or the frame of the gun. The spring forces can be reduced to the level that the mechanisms still function perfectly without the extra force. The interferences or friction between moving parts and their housing or the gun’s frame can be looked after. And the sear surfaces can be stoned and polished to reduce the sliding friction. Appropriate lubrication (oil on the rotating parts and moly-disulphide grease on the sear surfaces) can help as well.

One important often-overlooked situation is that any grinding or stoning or polishing of any surface must not remove the hardened surface as applied by the manufacturer. Some parts are made hard throughout but often only the surface, down to a few thousandths, is hardened. Removing that surface reveals soft under metal that will not hold a trigger job for very long. Such radical modification should include renewing the surface hardness or the trigger job will disappear quickly and perhaps the gun might even become unsafe.

THEORY OF THE MODIFIED COLT SYSTEM OF TRIGGER JOBS

Until the cost of labor started to drive the cost of guns upward Colt used a system of sear engagement that gave safe positive sear engagement angles, but reduced the weight of pull as well as the creep. AGI calls a modern adaptation of this system the Modified Colt System. The key is that the engagement is first made positive for safety then the actual sear dis-engagement motion is minimized. The notch depth usually remains the same but the sear is modified with an angle on its inner most surface (about 45 degrees) so that as the sear moves across the notch, the edge of the notch hits the angled inner sear engagement surface and the notch pushes the sear out of engagement. The actual engagement surface can be made small (less than 0.025 inches in most cases, not including the 45 degree sloped surface) but the sear is safe due to the positive angles. The short travel of the sear before the break and the small sear surface itself reduces the creep substantially. The cam’ing of the hammer (from the positive sear engagement angle) does limit how light the pull weight can be but the action of the system is so crisp (remember-breaking glass rod) that the pull weight does not seem as heavy as it actually is. This approach allows perfectly safe 2.5 lb trigger pulls that are creep free and safe on semi-auto center fire pistols but even 4 to 5 lb pulls seem much lighter due to their crispness.


PRACTICAL CONSIDERATIONS

This approach can be used on hammer guns striker guns, rifle, etc.. Some are much harder to implement than others but all guns can be greatly improved with this method. I have successful employed it on several guns. My only concern is all my other guns where I used different approaches that in hindsight might not have been ideal. None of those guns has been a problem but I sure wish I had known this approach earlier.

The one aspect of a trigger job not covered by this system is over-travel. For that the easiest way is to buy an after market trigger that includes a screw that acts as a stop against the back of the trigger guard. Adjust the trigger over-travel screw such that the gun will just not be able to be set off then add some over-travel to assure the gun will fire when hot or cold. Usually about a quarter turn of the adjusting screw gives enough. An alternative is to search out a place on the frame where a screw can be added to stop the travel of the trigger in over-travel. I had to do this on my Browning High Power. Interestingly, I also had to take off the magazine safety (gun could not be fired without the magazine inserted-a poor safety at best) to get the pull at all nice as the safety completely screwed up the trigger action. Be sure to LockTite these screws in place if they are not self locking. On still another gun the firing pin safety (firing pin can not travel unless the trigger mechanism pushes a pin out of the path of the firing pin) spring was way stronger than needed and was greatly affecting the quality of trigger pull. A lighter spring there still did the function but did not interfere with the trigger quality.

If you wish to do trigger jobs on a regular basis or have several guns to do I recommend getting the AGI course. About ten or more common guns are done on the video allowing you to see the pitfalls and to learn how to do it correctly to the finest detail. While the course is a little expensive its cost is less than a visit to the Emergency Room!
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Old 03-10-2007, 08:15 AM
armabill
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Are the sight rail screws interferring with the gun's operation?
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Old 03-10-2007, 08:15 AM
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Sounds like you "STONED" to much on the hammer and sear.
Next time just polish the hammer and sear.

John
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Old 03-10-2007, 08:22 AM
armabill
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I thought the same about the sear and that may be the case.

I was just wondering why the gun cycles OK with the rail off and won't with the rail on with the screws tightened. He also says that with the rail on and the screws loose, it cycles OK.

Odd.

Pics would really help.
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Old 03-10-2007, 10:08 AM
chim
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What all did you do? Something isn't adding up. I'm trying to understand the effect of the slide being off/loose/tight and the hammer falling.

There's no doubt that overdoing it with a stone will cause the sear and hammer to disengage when you don't want it to. It's the slide that has me scratching my head.

The only time I've had a hammer follow the slide on a Buck Mark is when the disconnector had a worn top, and didn't "disconnect". That pistol had probably 12,000 rounds through it and the underside of the slide was a little rough where it rode over the disconnector. First shot was OK but when I'd release the trigger so it would reset for the next shot, the hammer was already down. It never doubled when it did this.

Did you mess with the sear spring? Is the sear binding somehow?

I know it's probably frustrating for you, but it's an interesting problem with the sight rail having an effect. Tell us more.....................chim
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Old 03-10-2007, 12:47 PM
Skigeek

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Cool

I had the same problem last night. I completely disassembled my gun and polished the sear and anywhere else metal parts come in contact (i.e. the slide). When disassembled, everthing worked fine. I truly don't believe over-polishing the sear is the issue. What I concluded was (and I find it very hard to believe) is that I created too much space between the bottom of the slide and the frame of the gun. In other words, the sight rail was not keeping the rail close enough to the frame to engage the round-topped release on the side of the frame.

I think I resolved the issue by slightly stoning the rear screw post (for the sight rail) down ever so slightly which now keeps the slide closer to the frame, and seems to engage the release. I am going to test it today at the range.

I am amazed that a dremel and some Flitz could cause this though, so take my explanation for what it is worth.
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Old 03-10-2007, 12:49 PM
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Quote:
Originally Posted by LDBennett View Post
cbecker33:

If you read the following little article and the info is all news to you, then you made the first mistake of home gunsmithing: you took on a task that effects the safety of the gun without understanding how to do the job correctly.

LDBennett
I read that before I attempted to do anythying....I also read the dissection of a buckmark post and all of the info I could glean from this sight.

Time for my rant....

Do you think I would have attempted this unless I thought I reasonably could accomplish this task in a safe manner?

I tried, and I messed up, but how else are you supposed to learn anything? I don't think your snarky answer is at all called for....if I had come in and said "I took my dremel to my pistola to make it more better....my first time I took it too the range in went BLAM BLAM BLAM BLAM like a machine gun...do you think it was the ammo? " then I could under stand the apparant condecension.

Instead, I made a calculated decision to try something...then I tested it in a safe manner without putting anyone/thing at risk. Now I am attempting to trouble shoot. Please, take your snarky attitude elsewhere. Just because this is my first post, that doesn't make me a newbie with firearms or firearm safety.

Rant off.....

Sorry if that was not your intention...

Chris
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Old 03-10-2007, 01:03 PM
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Originally Posted by Skigeek View Post
I had the same problem last night. I completely disassembled my gun and polished the sear and anywhere else metal parts come in contact (i.e. the slide). When disassembled, everthing worked fine. I truly don't believe over-polishing the sear is the issue. What I concluded was (and I find it very hard to believe) is that I created too much space between the bottom of the slide and the frame of the gun. In other words, the sight rail was not keeping the rail close enough to the frame to engage the round-topped release on the side of the frame.

I think I resolved the issue by slightly stoning the rear screw post (for the sight rail) down ever so slightly which now keeps the slide closer to the frame, and seems to engage the release. I am going to test it today at the range.

I am amazed that a dremel and some Flitz could cause this though, so take my explanation for what it is worth.

Hmmm, you may be on to something...I noticed after I finished that the rear sight rail screw does not seat fully any longer....it only sticks up tiny bit, but it definately did not do that before.

Additionally, the safety lever no longer functions properly....I read Chim's earlier post about not forcing it in/out, so I was quite careful. But, when installed, the safty seem to "bind" when I raise up on the lever. If (with the grip removed) I apply pressure to the base of the lever arm (where the grip would normally cover) inward (towards the pistol) the lever engages/disengages correctly. But, without this support, it seems to "bend" at an angle and bind between the frame and hammer on the pin. It seems like there should be a shim on there

Your help is much appreciated so far....I'm off to stone the rear screw

Last edited by cbecker33; 03-10-2007 at 01:13 PM.
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Old 03-10-2007, 01:15 PM
Skigeek

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How I came to my conclusion is by reassembling the slide onto the frame without the recoil spring and assembly included. I then made sure the gun was cocked, pulled in and held the trigger, while manually moving the slide back and then forth. If you play with the position of the slide by 1) with your fingers applying pressure down toward the frame and 2) pulling up on the slide toward the sight rail and note any differences. What I found is that if by applying pressure toward the frame, everthing worked fine, but by applying pressure toward the sight rail, the release did not engage and the gun would not re-cock. A little distance seems to make alot of difference.
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Old 03-10-2007, 01:29 PM
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Originally Posted by Skigeek View Post
How I came to my conclusion is by reassembling the slide onto the frame without the recoil spring and assembly included. I then made sure the gun was cocked, pulled in and held the trigger, while manually moving the slide back and then forth. If you play with the position of the slide by 1) with your fingers applying pressure down toward the frame and 2) pulling up on the slide toward the sight rail and note any differences. What I found is that if by applying pressure toward the frame, everthing worked fine, but by applying pressure toward the sight rail, the release did not engage and the gun would not re-cock. A little distance seems to make alot of difference.

Hmmm...to further add to the mystery....I tried your suggestion above. I have found that with the spring/recoil assembly removed, the gun function perfectly if I fully tighten the rear sight rail screw and back the front sight rail screw off one full turn....

Chris
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Old 03-10-2007, 07:11 PM
chim
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[QUOTE=cbecker33;1350458]..I read Chim's earlier post about not forcing it in/out, so I was quite careful. But, when installed, the safty seem to "bind" when I raise up on the lever. If (with the grip removed) I apply pressure to the base of the lever arm (where the grip would normally cover) inward (towards the pistol) the lever engages/disengages correctly. But, without this support, it seems to "bend" at an angle and bind between the frame and hammer on the pin.QUOTE]

Safety removal and replacement should require no force at all. If you've ever played with one of those bent wire puzzles when you were a kid - it's kinda like that.

Grasping at a straw or two now. Any chance the safety click plate was installed wrong side out? Are all the pins properly in their places (including the reduced diameter pin that should be flush with the safety click plate on the left). Has the disconnector somehow become stuck?

Sure wish we could all be in the same zip code. I'd like to get an eyeball (and fingers) on those pistols..................chim
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Old 03-10-2007, 08:37 PM
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Quote:
Safety removal and replacement should require no force at all. If you've ever played with one of those bent wire puzzles when you were a kid - it's kinda like that.

Grasping at a straw or two now. Any chance the safety click plate was installed wrong side out? Are all the pins properly in their places (including the reduced diameter pin that should be flush with the safety click plate on the left). Has the disconnector somehow become stuck?

Sure wish we could all be in the same zip code. I'd like to get an eyeball (and fingers) on those pistols..................chim
Hmmm....I didn't have to pry at all....I did look a bit like a monkey with an a Rubick's Cube, but I got it apart with no force.

Everything looks ok, assembly-wise...I still don't understand why the safety feels so goofy....

I really don't understand why it functions with the front sight base screw loosened....I'll try to take some pictures tomorrow after I get back from shooting (unfortunately not with the Browning).

The disconnector does seam to be showing a slight bit of wear on the top (where the slide rides against it), but nothing too dramatic.
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