Trigger Pull Gauge Use and Revolvers...

E

Edward429451

Moderator
Is it normal to get different readings on different chambers when measuring trigger pull weight in SA?

I think it must be normal variance of the guns fit because they all varied, with the exception of my MDL 83, which gave the same pull on all 5 chambers.
 
I can't imagine how the sear would know which chamber was lined up. Are you sure the gauge is being used properly and exactly the same each time? What kind of variance are you getting?
 
Is there possibly dirt on some of the cylinders that would catch on the frame as they roll by? That's the only thing I can think of.
 
Single; No, Double; maybe

No, it is not.
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Keeping in mind that the OP has clearly stated that this is happening in SA. them as previously mentioned, it is not or should not be. You might get a slight variance but the cylinder is not in play, on single action. .... ;)

Trying to think of what I could be missing ??? ... :confused:

Be Safe !!!
 
You might get a slight variance...
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Slight variances are normal, but we need to wait for the original poster to give us readings. I believe some of the variance is often in the trigger pull gauge itself, since every one I've ever used includes a spring or two.
 
All gages have variation. Some more than others. I worked in quality engineering for many years. Some gages can have as much as 50% variation and can't be used in a controlled process. There is a process to calibrate gages and to do a gage assessment called Gage R&R (R&R stands for repeatability and reproducibility). I wouldn't get too excited about the gage giving different readings and if they are vastly different it simply says the gage isn't any good or it's defective. A very good gage will give variation but at an acceptable level. For instance, on a trigger pull gage the acceptable variation might be .25lbs or so. If you don't get any variation it means the gage probably doesn't read to a fine enough level or it's not a good gage either.
 
In my somewhat limited experience, strain gauge technology is a little more accurate than plus or minus .25 pounds. Maybe not repeatable to a one-tenth of an ounce as advertised, but certainly well under a quarter pound.

John
 
In my somewhat limited experience, strain gauge technology is a little more accurate than plus or minus .25 pounds. Maybe not repeatable to a one-tenth of an ounce as advertised, but certainly well under a quarter pound.

John
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John, you may be correct. I just picked an arbitrary number as an example. What I'm trying to say is that getting a variation in readings on a good gage, one suitable for the job at hand, is normal. If someone uses a good gage and it reads in small enough increments, you will see variation in all things. Gages that don't read in small enough (use the word discriminating here) increments it will appear that there is no variation. If a gage reads in very small increments, say ten-thousandths in linear measurement, and you measure rough castings, you will get a lot of different readings. However, all the readings may be within an acceptable range. Most less expensive, precise, gages don't read at discriminating levels. You need to know what the acceptable level of variation is and use a gage that will read to that level plus one decimal place (the descriminating decimal). Summary: make sure you have the right gage for the job and know what is acceptable (normal) variation.
 
It's a revolver, so the trigger swings on a pivot. The key to repeatable results is to repeat the experiment. The gauge has to be placed on the same point on the trigger every time. The gauge has to be pulled straight back every time. There can't be any sideways pull (off the barrel axis). The pull rod has to be positioned so that it doesn't drag on the frame or grips.

And the gauge has to be pulled slowly and gently enough that you STOP pulling when the trigger releases.
 
Delta - Pull !!!

And the gauge has to be pulled slowly and gently enough that you STOP pulling when the trigger releases.
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Along with the other good points you have brought out, the gun should be anchored or secured as to not move. Have seen many folks, including smiths, that hold the gun in one hand and the gauge in the other. ... ;)

Be Safe !!!
 
Probably no more than 1/2 LB variance, but that sounds like a lot to me. I think I need more practice with it. My variances was probably due to my funky triggers! That would explain why I had no problem getting the same and repeatable results with my FA 83. That gun has such a sweet trigger and breaks so clean that it really casts a shadow on my other guns triggers.
 
If the gun is held firmly ....like on a towel on a table ....and you are careful to pull from the same spot on the trigger ..and straight back ...you won't get too much variation ( maybe 0.2 of a lb ) ....

and for any given gun ....I usually take the measurement 8 or 10 times ...and throw out the high and low and average the rest ...

most of my S&W revolvers ...in SA ...only vary 0.1 lb .../ but the trigger pulls even in single action vary quite a bit from gun to gun ....( some of mine in SA are under 3 lbs....some are 3.5 lbs ...and a couple are a little over 4 lbs...) none of which I find unacceptable ...model 18's, 19's, 27's, 28's, 29's ....66's, 686's, 629's , 617's.....in my collection..
 
There are gauges, and then there are gauges....

I had one that was literally nothing more than a cheap ass fish scale with a trigger pull label on it...

In the Army Small Arms shops I worked in, the trigger pull "gauge" was a rod, notched to fit the trigger, with weights added on the end. You put the weight on the end, then lifted the gun (with the rod on the trigger), adding weights each time until the gun fired (snapped).

Uniformity of operation is key to uniformity of results.

Do it again (gun clean, and unloaded, of course), then do it several more times. See if there is a pattern. Then decide if the pattern is something YOU are doing, or if it is the gun.
 
This was the RCBS Fish Scale, sic. I will try it again when I can get my buddy over again, but it starting to be clear why there were difficulties at higher weights. He bought the wrong gauge...thx
 
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