Digital Trigger Gauge

[d31tc]

First, I’m a frugal (maybe cheap) guy. I recently installed a Timney trigger in a Savage Axis 223. I needed/wanted to test pull weight and lacking a trigger gauge, I made my own digital trigger gauge. Not really, but I made what I had work.

Digital food scale, a non slip surface, and a trigger to scale linkage (AKA a hanger). Zero out the scale with the linkage on the scale. Set up gun with linkage, set phone camera to video and hit record. Test trigger. Scroll through video and ID trigger release weight and screen shot for posterity. Worked like a charm. Tested out a few other triggers.

The plastic hanger yielded a little too much at heavier trigger pull weights, so a more rigid linkage would be better. Any L shape or c shape with proper dimensions would work. I used an open end wrench with the axis before I put the barrel and action back in the stock, but that wouldn’t work with the trigger guard.

 

[lysanderxiii]

Digital fish scale . . .

 

[230RN]

Ditto on the fish scale and a properly-bent coat hanger.

One thing I've always wanted to see in gun reviews is a graph of force versus trigger movement distance, admittedly because of a personal problem with long-ago damage to my trigger finger.

I have trouble with the "92" double action trigger because the weight itself is OK, but I can't pull it far enough with my right hand index finger. Personal problem, but I still think force-distance, perhaps measured to the back of the grip where the web of the thumb rests, would be a good addition to the specs. I do not have small hands.

Terry, 230RN

 

[d31tc]

Digital fish scale . . .

No doubt, an accurate fish scale would have been easier. I don't fish much, therefore I don't have a fish scale. So I looked at what I had laying around. Sure, I COULD buy an actual trigger gauge, but...priorities.

In case someone else is interested and is having trouble overcoming functional fixation, I figured I'd throw this out there as an option. I'll probably give it a whirl with every gun I have when I pull them out for spring cleaning.

 

[Bill_in_TR]

An archery bow scale would work too.

 

[Riomouse911]

Crafty solution.

Stay safe.

 

[TimRB]

I have a spring-based trigger pull gauge that I think is reasonably accurate, but normally all I want to do is confirm that my trigger meets the 4.5 pound minimum trigger pull for a CMP or NRA legal service rifle. So I load a bunch of bullets into a baggie (7000 grains per pound), tie a string around the top, put a loop in the other end, and hang it on my trigger. If I can lift my rifle without triggering, I'm golden. Functionally similar to the official check weights they sometimes use at matches.

Tim

 

[d31tc]

I have a spring-based trigger pull gauge that I think is reasonably accurate, but normally all I want to do is confirm that my trigger meets the 4.5 pound minimum trigger pull for a CMP or NRA legal service rifle. So I load a bunch of bullets into a baggie (7000 grains per pound), tie a string around the top, put a loop in the other end, and hang it on my trigger. If I can lift my rifle without triggering, I'm golden. Functionally similar to the official check weights they sometimes use at matches.

Tim

I like that idea. If you know what weight you want to set it to, easy enough to find a few things that add up to that weight. Not as tricky to hold it all together and more direct.

I suppose it would be easy enough with an adjustable trigger to hang the weight off of it and turn the adjustment screw slowly until the sear releases. Do a few rechecks, maybe bracketing the desired weight if you want, and good to go.

 

[Littlef]

One observation. I've noticed when I weigh things on my kitchen scale, they need to be centered on the pad. If I move the object from the center of the scale, towards the edge, I get different readings. Just something to keep in mind.

 

[d31tc]

One observation. I've noticed when I weigh things on my kitchen scale, they need to be centered on the pad. If I move the object from the center of the scale, towards the edge, I get different readings. Just something to keep in mind.

Good thought. I should test the error with some weight in the neighborhood of the results I was seeing. I was able to center the pistols on the scale, but offset the rifle for obvious reasons.

 

[230RN]

I have a spring-based trigger pull gauge that I think is reasonably accurate, but normally all I want to do is confirm that my trigger meets the 4.5 pound minimum trigger pull for a CMP or NRA legal service rifle. So I load a bunch of bullets into a baggie (7000 grains per pound), tie a string around the top, put a loop in the other end, and hang it on my trigger. If I can lift my rifle without triggering, I'm golden. Functionally similar to the official check weights they sometimes use at matches.

Tim

That's 185 170 grain bullets, 137 230 grain bullets. Huh.

On the other hand, you could count out 31,500 barley seeds to make the 4.5 lbs.

Terry, 230RN

 

[SSN Vet]

Popped for a Lyman many years ago and never looked back. Repeatability is key... and I like having the built in average pull feature.

 

[ms6852]

First, I’m a frugal (maybe cheap) guy. I recently installed a Timney trigger in a Savage Axis 223. I needed/wanted to test pull weight and lacking a trigger gauge, I made my own digital trigger gauge. Not really, but I made what I had work.

Digital food scale, a non slip surface, and a trigger to scale linkage (AKA a hanger). Zero out the scale with the linkage on the scale. Set up gun with linkage, set phone camera to video and hit record. Test trigger. Scroll through video and ID trigger release weight and screen shot for posterity. Worked like a charm. Tested out a few other triggers.

The plastic hanger yielded a little too much at heavier trigger pull weights, so a more rigid linkage would be better. Any L shape or c shape with proper dimensions would work. I used an open end wrench with the axis before I put the barrel and action back in the stock, but that wouldn’t work with the trigger guard.

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View attachment 1206946

View attachment 1206947

View attachment 1206948

I wanted to use two emoji's the lol and the heart and chose the heart. Have to give a ton of credit for thinking outside the box. I had to do that a while back on a Winchester 9422M that my brother gave me. It was missing the hood on the front sight and I ordered one. Darn thing was so hard to pull apart to slide over the front side that I too had to improvise by reversing my grips on an Irwin clamp. I believe if we had more redneck engineers in NASA we would already have colonized Mars.

 

[d31tc]

Popped for a Lyman many years ago and never looked back. Repeatability is key... and I like having the built in average pull feature.

Penny wise, pound foolish, I am . No doubt, a purpose built gauge is the best way to go. I Googled for tigger gauges and stuff and found Triggerscan. That would be fun to have as well, but right now I keep spending my money on other things. If anyone has followed my Axis rifle thread, you will know that I am now $475 short of where I might have been towards a S&W revolver because I sidetracked myself by shooting promising groups one day... Oh well, I had another rifle needing a dedicated scope anyway.

So, as you see, if I go down the route of buying an actual trigger gauge, I'll probably wind up buying a Triggerscan, and then how will I ever be able to afford a S&W revolver?

 

[d31tc]

I wanted to use two emoji's the lol and the heart and chose the heart. Have to give a ton of credit for thinking outside the box. I had to do that a while back on a Winchester 9422M that my brother gave me. It was missing the hood on the front sight and I ordered one. Darn thing was so hard to pull apart to slide over the front side that I too had to improvise by reversing my grips on an Irwin clamp. I believe if we had more redneck engineers in NASA we would already have colonized Mars.

Yes, but a lot of the rocket parts would be put together with bubbafied screws. But at least now I would have an idea of how to get them out...

and "We can get a little more orbital velocity of this sucker if we just compress the rocket fuel a little bit past what the manual says. Just check for flattened rocket engines and other signs of overpressure after firing."

 

[230RN]

Yes, but a lot of the rocket parts would be put together with bubbafied screws. But at least now I would have an idea of how to get them out...

and "We can get a little more orbital velocity of this sucker if we just compress the rocket fuel a little bit past what the manual says. Just check for flattened rocket engines and other signs of overpressure after firing."

Mike Hughes - Stuntman - Fan Website

Mike Hughes - Stuntman - Fan Website

madmikehughes.com

He knew how to drive a rokit. Up. Down not so much.

On the other hand, I got along great with my fish scale and a coathanger. Slight bending of the coathanger was immaterial as long as the direction of pull was the same.

I questioned "taking an average" in one of the above posts. If you have to take an average, it brings into question the adequacy of the method, no? And in a contest / competitive situation, you want to be positive your "reading average" was above the competition's rule requirement. Doesn't that make sense?

?
Terry

 

[J-Bar]

I have used a food scale to measure trigger pull also.

I hung a ziplock plastic bag on the trigger (poke the trigger through the upper corner of the bag). Cock the gun and hold it vertically and then pour lead shot (yeah, I was reloading shotshells at the time) into the bag until the trigger breaks. Then weigh the bag and shot on the scale. Remarkably repeatable.

 

[d31tc]

Mike Hughes - Stuntman - Fan Website

Mike Hughes - Stuntman - Fan Website

madmikehughes.com

He knew how to drive a rokit. Up. Down not so much.

On the other hand, I got along great with my fish scale and a coathanger. Slight bending of the coathanger was immaterial as long as the direction of pull was the same.

I questioned "taking an average" in one of the above posts. If you have to take an average, it brings into question the adequacy of the method, no? And in a contest / competitive situation, you want to be positive your "reading average" was above the competition's rule requirement. Doesn't that make sense?

?
Terry

Yep, depends on why we are measuring the pull weight. Average can be helpful. If the minimum required is 4.5 lbs, 4.5 lbs is probably not what you want to set the average to.

Of course I then went off and googled "mechanical error in trigger pull weight". Random, systematic, human and environmental errors. I'm not going to calculate the uncertainty in my measurements, which I'm sure is fairly high. But, I'm reasonably certain that they are within the acceptable limits for my application. OK, who am I kidding; yeah, I'm definitely going to calculate it when I have time.

First few pages of the attached link show methods of measuring trigger pull presented here that I didn't think about prior to my method, then my ADHD got to me - SQUIRREL! So I didn't get to the uncertainty calculations.

https://www.nist.gov/system/files/documents/2020/03/23/OSAC%20Trigger%20Pull%20Std%2012-16-2019.pdf

 

[AzShooter1]

I finally gave a Lyman Digital Scale to my shooting buddy. He had no idea what his pull was on a variety of guns but swore that they were in the 5 - 7 ounce range. After testing with the Lyman they came out at over 1 1/2 pounds.

He just replaced the trigger in his Savage Mark II and was having trouble with the trigger resetting. It was too light but after using the gauge he could tell that it was 1 pound and needed 1/2 more to work right.

Sometimes you just need the proper tools to get the job done correctly.

 

[rust collector]

Brilliant idea to get one for your buddy, so he can store it and you can use it when needed!

I have had the Lyman old style for a number of years. Always amazed me that the trigger pull on my Tikka was slightly different every time. Maybe it was my technique, but I avoided the ragged edge of reliability with that unit and it is fully amortized these many years later.

 

[SSN Vet]

Trigger pull is pretty subjective. You either like it or you don't. So a pull gauge doesn't really add much value, unless you're working on the gun. If you're smithing to improve the trigger pull, then having the gauge gives you something objective to quantify your work.

 

[d31tc]

Trigger pull is pretty subjective. You either like it or you don't. So a pull gauge doesn't really add much value, unless you're working on the gun. If you're smithing to improve the trigger pull, then having the gauge gives you something objective to quantify your work.

I guess you could say I was working on the gun to improve the trigger pull, but pretty much a drop in trigger. Not really gun smithing in any technical sense to improve the trigger pull, but since the trigger is adjustable, I wanted to make sure it wasn't set too light (for my purposes). I haven't messed with adjusting trigger weights before, all of my other guns are factory triggers at factory settings. I guess my triggers in my Tikka and SAKO are adjustable, but I haven't messed with them. I just might ...

FYI, out of curiosity, I got a price for a Triggerscan. Yeah, that's out of my price range by about a factor of 100 and obviously not intended for everyday home use. That kind of money could buy 4 or 5 of guns on my list or a scope that far exceeds my needs.

 

[rust collector]

One thing I discovered with my Lyman trigger pull scale is that when I set the trigger of my Tikka T3 near the lightest end of the pull range, readings became more erratic. Getting back off that ragged edge made the trigger pull more uniform and positive.

 

[Reloadron]

Measuring trigger pull force can be as simple as a common fish scale, as in even an analog mechanical scale or a digital scale. A few dollars give or take. Like anything else gun related we can also get as expensive as we want adding features. We can go digital and resolve 0.01 Lb or even 0.001 Lb and if we choose we can measure travel of the trigger as we apply pull force.

This is an old Ametek (Chatillion) force gauge. I used this gauge extensively during the early 90s. It's 0 to 10 Lb and easily resolves 0.1 Lb.

Today if I wanted a new version I would likely roll my own using electronics and measure force applied plotted against trigger travel. A tension load cell transducer for force and a transducer for trigger travel.

The question begs how deep pockets are and what features do we really want / need? While I have no clue what a "trigger scan" unit cost I am pretty sure unless doing triggers daily anyone really needs one for a few one and done operations a year.



Ron