Trigger Creep Theory

[Wichaka]

Here's something I was pondering yesterday as I was doing a trigger job on a TRP.

All trigger pulls have some creep........

No don't get your tails in a knot 'til I give you my theory. It may not hold good 'ol h2o, but its food for a good THR discussion.

So here's the parameters.......

I generally use Brown's Hardcore Barstock Hammers, which come with the hooks already cut at .020
Now if the sear nose out of the box is ......say .020, then you stone off the relief angle, which some say 1/4 of the total nose, where Brown says 1/3........so since we're using a Brown hammer........let's go with the 1/3 figure. So that leaves .013+ of sear engagement. Which means the trigger will have .013+ of creep........no?
Because the sear must clear the hooks of the .013+ engagement before the hammer will fall.

If my theory blows...........oh well. Just was doin' some thinkin' while working on this gun.

 

[RJ357]

That's my understanding of the term.

If a trigger has "no creep", I think it's more a matter of it not being noticable, not that there actually is none.

Sometimes it cannot be felt. The trigger seems to go through only break and overtravel (or takeup, break, and overtravel).

 

[mete]

You're not dealing with a theory , you're dealing with a definition.And that it the correct definition. You can however reduce the distance and make that creep smooth so it isn't noticed. In other words if we can safely reduce engagement to .013" and that creep is a light consistant 4 lbs throughout the pull you have a nice trigger. And then don't try to outguess the trigger , just apply a smooth increasing pressure and don't try to anticipate when the break will occur.

 

[1911Tuner]

Creepy!

Yep...There has to be some creep in a conventional sear/hammer relationship. The sear has to move far enough to get away from the hammer hook(s) The trick is to make that movement so short or so light
that the finger can't feel it unless pressure is applied at a very slowly increasing rate...or to keep the pull relatively heavy so that finger pressure is forced to over-compensate for the resistance...so that when the break comes, you can't tell which was creep and which was overtravel.

"Creep" is most often noticed when the travel is rough or gritty, followed by
mushy. Many times, what is known as a "Rollout Break" is perceived as
creep...which is correct...but if it's a smooth rollout break, most people can live with it unless the gun is purely a target pistol. I prefer a clean rollout break. Others may find it unacceptable.

Perception of creep can also come from a negative sear engagement...One that puts the tip of the sear slightly below the angle of the hooks. This can be observed by fixing the pistol in a vise and zeroing a dial indicator on the
cocked hammer and slowly pulling the trigger. If the hammer moves a few thousandths forward before it breaks...the engagement is negative.
If the hammer moves back...overcocking...the engagement is positive.
No hammer movement is neutral, and the neutral engagement is where the
cleanest, lightest trigger pulls come from. I prefer a slightly positive engagement. One that will overcock the hammer about two thousandths,
but becomes close to neutral as the sear tip reaches maximum height in the hooks...and turns into a negative engagement just before the break
by means of the breakaway angle. A rollout break that offers a little extra hedge against wear-induced hammer follow. These tend to last long and get sweeter with use. It also tends to offer a little insurance against bounce-induced hammer follow or trigger "staging" by working to recapture the hammer hooks and pull the sear back toward the bottom.
Staging the trigger is pretty much the same as having a thumb safety that
allows a little sear rotation...pulling the trigger hard with the safety engaged...wiping the safety off...and having a very short, light trigger pull
because the hammer hooks are only partly on the sear.

I've seen savvy bullseye shooters do this little trick in order to have the lightest pull possible...engaging the safety and staging the trigger between shots. It works...but it's not recommended, especially on a carry gun. The effect is a lot like a double set trigger. I've measured such
"tuned" systems at just over one pound trigger pulls while maintaining
4-5 pound pulls when allowed to function normally. Again...I do NOT recommend this little trick...but it does provide the safety of .025 or longer hooks, with the break of .015 hooks. At any rate...it's for "Toys Only" and
should never be used in a carry gun or action game gun.

 

[JeffC]

hrm.... "trigger creep".... I think I know that dude....

Seriously, I always thought of creep as what you feel in a long rough pull. I liked the way Colt had the .030 hooks that gave you a smooth rolling pull, never considered that to be creep, just sear travel.

BTW, Caspian hammers come with .025 to .030 hooks for those who like extra meat on their hammers.

 

[1911Tuner]

Caspian Hammers

JeffC said:

BTW, Caspian hammers come with .025 to .030 hooks for those who like extra meat on their hammers.
_________________________

Now, THAT'S good to know! hmmmm..I may hafta give Gary a call in the next week or two.

 

[HSMITH]

Wichaka, I think you hit the nail on the head. A smooth light 'creep' is transparent to most shooters.

For carry guns or game guns I like 25 thou + on the hooks, and about a 4-4.5 pound pull. I like a trigger with some creep, that way I KNOW when it will go off. As much as I have tried I just can't subscribe to the theory that the trigger break should come as a surprise. When I KNOW when it will fire I can place my shots faster and more accurately.

 

[1911Tuner]

I Wanna Know

HSMITH said:

When I KNOW when it will fire I can place my shots faster and more accurately.

Mr. Smith...I think me'n'you was whittled outta the same chunk of hickory...
'cept I like about 5 to 5.5 pounds. If I've got a positive engagement, I can take up the pretravel and put around 2 pounds on the trigger without havin' an AWHELLAWSHEEEEIT!-type surprise. It breaks when *I* want it to break..not when it decides to.

 

[Jim K]

I am with JeffC on the definition of "creep". Of course any trigger pull has some movement, more or less discernible, but a good trigger has no creep.

Trigger/sear movement of itself is not "creep" as I have always understood the term. "Creep" is an uneven, jerky pull, one that varies during sear movement before release. It is usually caused by crossways machine or file marks in the full cock notch of a hammer, but can be caused by friction in the absence of lubrication. "Creep" can be eliminated; sear movement cannot be, at least in a conventional firing system (electric/electronic systems are another story).

A smooth pull, with a smooth sear and sear notch, has no "creep" though it may have considerable movement. A smooth pull is usually no hindrance to accuracy, even if it is long or hard (within reason). Many people, including yours truly, shoot very well with double action revolvers; even the long and relatively hard pull is no problem as long as it is smooth.

Jim

 

[Wichaka]

Tuner.........do you know of any after market hammers that have more meat on their hooks? and are still solid steel? Will check on Caspians.......are there others?

I like my hooks at .023-.025, and my final pull at 5lbs. Have been doing this for years and have had no problems..........well one. Its when folks bring their guns in after reading the gun rags or 1911 mod. books, and they all want their hooks at .020 because that's what they read, and that's where they should be...........you get the picture.

They tell me that if the hooks are longer than .020, there will be alot of creep. So I do the trigger job and when they feel no 'creep' (Jim, you & I have the same definition of creep....uneven movement) they say perfect. But then I tell them that I set their hooks at .023+........another satisfied customer.

Okay........now an unofficial poll.........
How much do you take off the sear nose for the relief angle?

I'll go fist. I set my primary to match with the hammer hooks, then go somewhere between 1/4 - 1/3 relief cut of the total nose.

 

[1911Tuner]

Gritty, Creepy Creep

Interesting observations all around. I've always personally defined creep as perceptible sear movement after take-up but before hammer fall. I
have separate classifications is all. Smooth creep...gritty creep, etc.
Smooth I can live with...if it's not much movement. Gritty has gotta go!

Wichaka...I don't know of any aftermarket suppliers of machined steel hammers with hooks longer than .020 or .021 inch. Maybe C&S...?
I like Colt's undersquare geometry, because I prefer a light captive angle.

You also know by not that I don't do those 3.5 pound, hair trigger jobs on any 1911 in .45 caliber. The 9mms are a bit less violent, so they allow a little more leeway...but the 45s don't go under 5 pounds...period.

I do very light breakaway/escape angles...just enough to make a shiny line
across the side opposite the primary to make sure that there's not a sharp, ragged edge on the primary. I also put a very light, matching bevel
on the half-cock so that it acts as a camming surface in case of light sear contact as the hammer goes past the sear. Nothing that would affect the function of the half-cock...just enough to provide a little room for error for when the hammer is lowered and the trigger isn't quite fully rearward. One lick with a smooth file and one with a medium stone is about all it takes...just enough to break the corner.

Short, square hooks make me nervous. I've studied the design so much that I've given myself a headache a few times...trying to understand why
everything was done. I've come to the conclusion that nothing is incidental,
and that there's a very GOOD reason why everything is as it is...and that it's best not to dink around with it too much. Browning used undersquare
hooks for a reason...The dimple on the magazine follower is there for a reason...The trigger pull is specified as 6-7 pounds for a reason....and so on. I stopped trying to outsmart the man years ago, and began working
within his parameters as closely as I could. That approach has worked
well in making the pistol reliable for me...There's more to reliability than
just going bang every time. It's got as much to do with the gun continuing to function correctly for many years as it does with its basic task of firing and cycling.

Anyway, That's just my way of thinking...Yours and others' may vary somewhat.

Luck!

Tuner

 

[Wichaka]

Tuner I think we've jawed enough to know that we don't think too much differently. When I do my L.E. builds, all come out of the shop with 5lb+ pulls on them.

Its just lately I've been getting a bit discouraged over some of the aftermarket parts. I know why they cut the hooks to .020, because Wilson and co. have written about it so much that most everyone wants them that way, so they please the public. And of course, they sold many that way.........so others followed suit.
But there are a few of us that KNOW that triggers can be just as nice with hooks in the .025 range, along with pulls at 5lb+.

Not to toot my own horn here, but I've done some triggers that came out so smooth I thought I would have to adjust the leaf to add to the weight. But when I put the pull gage on it, it was over 5lbs.

Maybe we should start getting on the manufacturers to come out with more 'gunsmith' type parts. So those of us can tune the parts as WE see fit.

I just like a bit more meat on my hammers and sears.

 

[Dave Sample]

Perhaps the Grim Creeper creeps into the parts and does his thing! My triggers were all 56 oz. ( 3 1/2 lbs) with .019 hammer hooks. So far , so good. I have never had one follow or drop to 1/2 cock yet. I always have the hammer hooks cut on a mill before I start with the sear nose and stone those angles in. I use Ceramic Stones in fine and extra fine which works for me. I want a nice smooth, repeatable break that is friendly and safe. I have never liiked JMB's original angles because I don't have to. I like 90 degree hammer hooks hooks so that I have one place to start from that I can trust. Creep can come from other places and those places have to be addressed as a matter of course while doing any trigger work. I won't bore you with all of those places as I am sure Tuner knows all about them, as I do. The sear/hammer engagement is just one small area of trigger work. The folks I worked for back then liked these triggers and so that is what I gave them. I like 5 lbs for my carry guns so that is what I do for myself. I am not fussy about my personal guns as long as they are smooth and friendly.

 

[Wichaka]

Dave,

in another thread that was going sometime ago, I think it was about trigger jobs, you showed a pic of stoning the relief angle on a sear without the legs of the sear on anything............so in actuality you were stoning the whole sear. Whats your take on that? I take it that's how you were trained ?

 

[Dave Sample]

I am self taught and have learned everything the hard way. I took that picture for one of my Students in the Online 1911 Class so he could see how I do the "Break Away" angle on the lower sear nose. This a "Creeper Killer" that we do. The disconnector can cause Creep also so we work these over pretty good. All of our PATRIOT Triggers have come out pretty good for first time builders. Not up to" Teddy the Great's" high standards, but good enough for Jazz. We use really good MIM components that are Compatible with the Caspian Lower ends. This stuff is made just for us ( and whoever else wants to buy it) and it works great. Colonel Bob Young of Gunsite tried six of these 1911's and the trigger pulls were good enough for him. The COP ( Carry On Patrol) is a tough, flat black duty weapon, not a toy. It was put together by yours truly many years ago at the gunsmithing school at Yavapai College and has served us well. I just found out three years ago that this was very close to Bob Young's (Gunsites General Manager) specs for a great Marine Corps 1911. I taught 18 people in that NRA Summer Course and my worst student was the only one attending the College. He was geting too much advice from the gunsmithing instructors and did not do as I wished. He did produce a relaible nicely done 1911, but he was a hard one to work with. The instructors there did not like me at all because I did not do the things that they did. They have all been replaced now and went on to better things. There in a huge difference between a 1911 Pistolsmith and a gunsmith. Gunsmiths have to do everything. We are Specialists. I take my long guns to a Gunsmith. I do my pistols myself.

 

[1911Tuner]

The Breakaway Angle(Kinda long)

I was a little curious about that too, Steve...Let's take a look at the breakaway angle. Being a toolmaker has given me much opportunity to
study geometric angles and their effects on a part, and the breakaway angle on the sear is just another one.

Let's go ahead and agree on the point that a correct sear/hammer hook relationship requires that the hooks and sear primary angle should be in agreement...That is, the hooks' entire length should sit flat on the sear.

The breakaway angle shortens the primary engagement surface, so that less of the sear primary is involved in the engagement. Less surface
engagement means less friction and a lighter trigger...but the breakaway angle also reduces the amount of sear travel needed to escape from the hooks and allow the hammer to fall...and it does this without making the hooks any shorter. It makes for a nice, crisp trigger that employs the least
possible sear movement before the break...and greatly reduces the amount of creep.

Let's imagine a giant sear and hammer. The hooks are 25 inches long, and the sear primary is about the same width. The part of the sear that stops the sear against the bottom of the hooks is the backside of the sear. If we stone the backside of the sear parallel to the legs, we change that, and cause the sear to rotate farther into the hammer...and the sear and hook relationship no longer agrees...no matter if the hooks are dead square or undersquare.

The more we stone...the more of the primary we remove...and the farther
the sear will rotate into the hammer. The farther forward the sear rotates,
the more the engagement angle changes, and we soon have the tips of the hooks engaging the rear of the primary angle. When the trigger is pulled slowly, the hammer begins to roll forward as it tries to maintain contact with the primary. When the sear rotates far enough to again
be in agreement with the hooks, the amount of travel remaining is very short. In such a sear/hammer relationship, just a little inertial bounce can
set the sear up for a nearly set-trigger type of letoff. Dangerous, IMO.

BUT...if we place a shim under the legs to rotate the tip of the sear at a downward angle so that we cut mainly on the tip, the backside of the sear...the part that acts as a stop...isn't changed. When the hammer and sear are assembled, the hooks and primary sear angle are still in agreement because we stoned it on an angle that wouldn't cut any of the stop surface away. In order to accomplish this, the bottom of the sear must be raised about .020 inch...but in some cases, a .022 or even a .025
shim is required...but .020 will generally do nicely if other things are pretty well in spec.

The only way to regain agreeing hook/primary engagement is to recut the sear's primary angle. If we stone the breakaway without this shim to provide the breakaway angle AFTER we set the primary, the agreeing hammer/sear engagement is lost. Using a shim to cut the breakaway preserves the hammer hook/sear primary relationship.

Whew! Gotta go get the dogs fed...

Later on, ya'll!

 

[Wichaka]

Another area of concern that I see stoning the relief angle without a shim under the legs..........you're also stoning off the lug where the thumb safety makes contact.

Now granted we're not talking about alot of stoning..........or are we Dave?

Don't think I got your take on how much is stoned away on the relief angle.

So if you run .019 hooks, how much sear nose are you leaving for engagement, after the relief angle is cut?

Could you walk me thru your sear stoning process. I've not heard of doing it this way.

What stones do you use..........do you use a sear jig? If so what make.........etc.

 

[Dave Sample]

I think that this is the picture that you saw online. Notice that there is NO shim, that the part of the sear is only touching the break away angle and the flat part of the sear that has no effect on the sear engagment. When you rub the sear on the ceramic stone, you are putting the pressure on the nose of the sear and the other surface is just smoother very lightly. This is called doing two things at once. By stoning a little at a time, you can get the amount of angle that you wish as trigger work is cut and try maybe 25-50 times if you do it right. I use a break away angle that can be up to the same amount as the primary angle depending on the specs of the 1911 that I am working on. It is NEVER more than the primary angle. The Big Rule of trigger work is to ALWAYS see what you have before you start cutting. I cut the hammer on a digital mill to 90 degrees and reduce the hammer hooks to .019-.020. I clean up the cut with an extra fine ceramic stone (From Brownell's) and then I have a place to start that is a known dimension. The sear is tried before it goes into the jig by smoking it up with a blue marks-a-lot permanent pen and we assemble the parts and try a few pulls. I boost it lightly ( I would never even dream of using a screwdriver) with my thumb and take it apart. The white marks on the sear tell the story and where I need to balance the sear to the hooks. I have never changed the set screw in my Wilson sear jig since I found the Magic Setting 20 years ago. I have the right angle there for a 90 degree hammer. Then I start to mess with the Grim Creeper by cutting and trying until I get the desired trigger break. I adjust the sear spring as I go with a trigger pull gauge that has a mark on it at 56 oz. This can take up to two days at the worst and two hours at the best. I am presuming you already know the other factors involved with trigger work such as dealing with the trigger stirrup and where it lives. I hope this helps you a little bit.

 

[1911Tuner]

Shortened Version

Dave...What Wichaka's gettin' at is that..If you stone the breakaway angle without the shim under the bottom, you're losing the area that stops the sear and causing it to rotate farther into the hammer. The edge of the
primary that was sitting squarely in the hooks is now pointing downward,
and all that work that you did on setting the angle just so...is gone.

When you raise the bottom of the sear so that the breakaway is stoned on a steeper angle...closer to 45 degrees...the stop point isn't altered, and so the precise engagement with the hooks is preserved. What he's trying to determine is: Is there a reason that you want the tip of the sear to sit below the bottom of the hooks?

I'm not a trigger man, and I don't know all the little tricks of that part of the craft. If there's a reason for it...clue us.

Standin' by...

 

[Dave Sample]

I am sorry that I can't make this clearer. I use a .020 shim on the primary angle on the sear nose to set the hammer hooks where I want them for a good, solid, safe, engagement with an old Wilson (Tom) sear jig. Then I do the break away angle to lighten the pull and get rid of most , or all, of the Grim Creeper. That flat that gets smoothed out a little does not touch anything except the thumb safety and it is fit later so it makes no difference. The little bit that I smooth it makes no difference to that fit, either. I will try to get some pictures later that might help. I have just received a Trigger Group that Ted Yost sells and the sear has a break away angle already cut. Tuner is used to a GI type trigger engagement which is different than what I do. There are many fine pistolsmiths that can tune these angles perfectly, but I am not one of them. I do not have to be since I have built more guns from scratch than I have factory gun tweakin'. If I do trigger work on a factory 1911, I use all new parts.

 

[Dave Sample]

The Tale Of Two Sears. One is the one I used 46 times, and the other is a new sear from the Ted Yost parts.



What you are seeing on the left is the break away angle. The sear I use does not have that feature.



Two very different hammers. One is the one I like and the the other has a notch in it under the hammer hooks.



Here is how the sear, disconnector, and the hammer are arranged on the outside of the gun. Notice how the sear engages the full cock notch with the tip in the notch in the hammer.



This is the trigger group I prefer. A totally different engagment that I hope you can see. Remember that these parts are new and have not been touched yet.



Parts in the gun with the hammer at rest.



Hammer at 1/2 cock.



Hammer at full cock. Notice that the little bar on the sear does not touch anything in any postion.

 

[Dave Sample]

Here are the two sets of parts , both new out of the bag. The ones I use are the black, ugly ones.



The two hammers have different serrations. One is 20lpi and the other is 30 lpi. I love to checker the 30 lpi so this one will get it.



This is a nickle plated thumb safety that has already been fitted to a 1911. Note the fitted area in blue ink.



This is a new one and the thin line is where you begin to file the cut. It also shows the way we put it in the vice.

 

[1911Tuner]

Escape!

Good pix, Dave. Thanks mucho.

The point that I'm tryin' to make is that...if you stone your primary first, and stone the escape angle without the shim AFTER the primary is set, the area that you're stoning for the escape angle removes material that stops the sear's movement during reset into the hammer. The sear rotates farther, and you lose the agreeing engagement between the hooks and the sear primary angle...Is that on purpose? Is the reason because you want to delay the point that the tip of the primary touches the hooks so that the dwell time of maximum resistance is reduced, making the pull feel lighter than it actually is?

The way I'm seein' it, the sear primary and the hooks would come back into agreement after a few thousandths of sear rotation so that maximum resistance is on the tip of the sear for a slightly shorter distance before the hammer breaks.

Standin' by...

 

[Wichaka]

Okay........I've added a crude drawing of the question that Tuner & I have.

Tuner & I cut the primary angle on our sears to match the hammer hooks. Then by cutting the relief angle while the sear legs are on a.......say at least a .020 shim, there's always a built in stop that makes sure the sear doesn't rotate further into the hooks, thereby disengaging part of the primary angle from the hooks.

My question............Tuner may have others.........

From your posts Dave, I take it that you really didn't learn it anywhere..........you've just done it on your own?

The other question..........which is actually Tuner's
Are you trying to get the pull to feel lighter than what it is? By doing it that way?

Although I will say one thing, I got a 1911 in the shop this last week that has had a trigger job done by Wilson some years ago. The first thing I did was strip it down to see some of their work. The trigger pull was at 3.5 lbs........56oz, before I got ahold of it........but the interesting thing was that the sear had a round nose on it. The hooks just sat on the round nose, and the nose itself was very thin.......like that from what I've been seeing on SA's. No primary or relief angles..........just a rounded sear nose. The guy said that he has never messed with anything, that it came that way from Wilsons shop.

Not what I'm used to when doing triggers.........

 

[1911Tuner]

A Picture is Worth...

Wichaka, thanks for the drawings...but if you'll go to Dave's sear, and move the vertical line to the right a little, and lop off that corner just to the right of the word "Relief"...THAT's what I see happening when the sear is laid flat on a stone without lifting the bottom with a shim.

That corner that you'll lop off is what stops the sear when it resets into the hammer. Stoning it at a nearly 90 degree angle would remove that stop, and let the sear rotate deeper into the hooks...The primary would no longer
be level, but would angle downward, and the hammer hooks would no longer be sitting flat on the sear.

The effect would be the same as setting the sear primary angle and then
using a square file to make the hooks deeper. The sear wouldn't stop at the same place, and the agreeing sear/hook engagement would be history.