Trigger pivot point

[PathfinderNC]

What would be the optimum distance from the trigger pivot pin to the sear bar (on a Fowler or rifle)?

 

[TDM]

The longer the distance, the higher the trigger pull. 3/4” to 1”? Honestly I’ve never measured exactly.

 

[The Crisco Kid]

The shorter the distance the less the creep. I've been told that 1/4" to 3/8" is optimum and it seems to work well for me. This is the distance you're asking about, from the pivot to the sear bar. The higher the pivot pin from the trigger itself the less the amount of pull weight it takes to move the sear. It's the same idea as using a bar to lift or move a heavy object. The pivot pin is the fulcrum and the shorter the distance from the fulcrum to the object and the longer the bar the less force is required on the bar to move the object, in this case the sear. Probably good I'm not a physics teacher, that's sort of a muddled lecture.

 

[TDM]

It’s easier for me to draw a picture than explain it properly.

 

[Phil Coffins]

And the shorter the leverage the longer the travel, aka creep.

 

[IanH]

The closer the trigger pivot to the sear bar, the more creep you get at the sear to tumbler contact, but much less pull weight.

The creep you don't want is from the trigger being pinned too low. The trigger should be pinned on a line drawn between the sear pivot screw on the lock and the bottom of the sear bar, that way the trigger bar and sear bar don't have to slide across each other very much as they trace their arcs of travel at the release point. I wouldn't put the trigger pivot closer than 1/4" to the contact point on the sear bar or more than 3/8" away. My fowler has the distance set at 5/8" and it is very crisp but runs about five pounds.

 

[Eric Krewson]

I get a 2.5 to 3# trigger with the sear contact 5/16" from the pin.

 

[Capt. Jas.]

Most original birding pieces i have taken apart were pinned 5/8" from the sear bar. Go on ALR and there are a couple of very informative threads on this with input from quite a few knowledgeable people.

 

[The Crisco Kid]

Here'a a photo of a new trigger with the sear location marked. You can see that the trigger pivot pin is a long way from the center of the trigger which gives the leverage I mentioned earlier. The trigger bar should be filed off at a slight angle so that it's not trying to force the sear nose into the tumbler notch. Of course, the tumbler notch needs to be at the correct angle relative to the tumbler pivot and the sear nose needs to be at the correct angle relative to the tumbler notch. The lock maker supposedly has done this for us. The trigger bar will no doubt have to be filed lower to fit the sear bar when they are in the stock and that silly roll pin will be replaced. As mentioned, there should be a little clearance between the bar and sear at both full and halfcock.
Also, I'll have to install a shim between the trigger bar and the housing to get rid of all the side to side slop. This makes a big improvement in how the trigger feels. I use old feeler gauges for this usually about .015". I super glue the shim in place and the drill through it from the opposite side using the hole as a guide.

 

[IanH]

Trigger pivot to sear bar orientation is still less than ideal. If the trigger is filed to the sharpie line and moved up the amount of the blue line, it will improve the intersection angle considerably (green line), but ideally the trigger pivot should be moved up twice as far to be ON the red line along the sear bar so the two imaginary lines are parallel. This isn't possible with most trigger assemblies I've seen, so I either make my own or pin the trigger in the stock directly through the line drawn through the sear pivot to contact point on the bar.

 

[The Crisco Kid]

You're right, it can get complicated and difficult to get to the ideal. If I can get a 3 lb. or so pull with no creep it's a good hunting trigger for me and I seem to do OK offhand target shooting.

 

[Eric Krewson]

I forgot to mention; all my single triggers are homemade, pinned through the stock and not connected to the trigger plate.

Like this, except that the trigger is laying on the lock molding and nowhere near where it will end up after being inletted in.

 

[PathfinderNC]

I forgot to mention; all my single triggers are homemade, pinned through the stock and not connected to the trigger plate.

Like this, except that the trigger is laying on the lock molding and nowhere near where it will end up after being inletted in.

View attachment 262602

That's a helpful picture, Eric. It shows how to place the trigger very clearly. Wjhat do you mean "nowhere near where it will end up after being inletted in."?

 

[Eric Krewson]

I have to install the lock and see where the sear is. I inlet the trigger slot and move the trigger around until the bar is very slightly above the striking surface area of the sear and the right distance away, I check things with lamp black on the sear to see where everything is hitting. At first I only drill a short hole in the lock inlet and through the trigger to make sure everything is in the right place, so far, I hit it just right on the first shot. After I get the trigger pinned, I cut away a lot of the unneeded trigger material that you see in the picture I posted.

I make my own trigger plates and inlet them so they take any slop out of the trigger and prevent any excess trigger movement to the front.

Like this, an English Fowler with a correct offset slot and proper shaping. Back when I built this gun there were no English fowler trigger plates to be had at any of the parts suppliers.

I realize the trigger isn't anyway near correct for a fowler but I was playing around with the shape and said what the heck, I like it, done deal.

 

[bldtrailer]

just a side note SHANE FROM CABIN CREEK inspected my build with a 3lb+- trigger(5/8ths from pivot pinned through the stock) and showed me that I had to much contact with the sear by striking the back of the cock at half and full cock causing a release (I was able to correct by more filing of the trigger till there was no contact at half/full cock) Thank you Shane !

 

[Norman Brooks]

Moved the trigger pivot point back .280 on a Kibler Woodsrunner. Done a little polishing on the tumbler and sear. Trigger pull is 2 1/4 pounds with no creep.

 

[PathfinderNC]

Moved the trigger pivot point back .280 on a Kibler Woodsrunner. Done a little polishing on the tumbler and sear. Trigger pull is 2 1/4 pounds with no creep.

That’s good. Did you use the same pivot hole that was in the trigger bar or drill a new one? I do have a bit of creep on my Woodsrunner that I don’t like.

 

[James Kibler]

If you move the trigger pin closer to the sear arm, you will increase pull distance (creep). There is no way around this. It's always a compromise between pull distance and pull weight. They are tied to each other.

 

[Norman Brooks]

That’s good. Did you use the same pivot hole that was in the trigger bar or drill a new one? I do have a bit of creep on my Woodsrunner that I don’t like.

Used the same hole in the trigger. As stated by others, including Jim Kibler creep will increase. If you have never tuned a lock I would not recommend playing with the tumbler to reduce the creep, you could be causing an unsafe condition by not staying on full cock. This is my 2 cents worth and I'm sure that others will supply their 2 cents worth also...

 

[Eric Krewson]

I have on several occasions added a little metal to the top of a trigger bar when I had a little creep. I harden a piece of steel and soft solder it on top of the trigger bar to get the trigger right up against the sear. I may adjust my add-on with a little filing then polish it to a mirror finish.

I added about 1/8" of steel to one single trigger that was already pinned (first rifle). Then there was my pre-carve from hell rifle with a 3/8" web, I couldn't go any deeper with the trigger plate because I started breaking into the ramrod channel so I started adding metal to the trigger so it would reach the sear. I didn't have to add any metal to the set trigger, it pops up high enough to do the job it is intended to do.

The first go round wasn't quite enough so I added a little more, looks awful but it works flawlessly, the front trigger unset breaks at 3 1/2# with no creep.

The moral of this story is don't buy a pre-carve from any place that does multiple duplicates at one time, especially if they have already done the lock inlet.