This weekend I replaced the factory trigger with a drop in adjustable trigger on a AR10. I know 3 guys that have a new Lyman, a new Timney mechanical, a Wheeler Digital and a NRA weight system for checking triggers. I adjusted the trigger pull to try for an average weight of 3 lbs 8 oz using the Timney mechanical gauge.
Each gauge was tested with 10 pulls and averaged. A slow and parallel pull was used.
Using the NRA weight system 3 lbs 12 oz could be used on the trigger and the trigger would not break. By adding one more ounce for a total of 3 lbs 13 oz the trigger would break every time. Using this system the butt of the gun was placed on a table letting the weights hand free for gravity to work.
The Lyman Digital gauge averaged 3 lbs 7.7 oz. The highest reading was 3 lbs 9.7 oz. The lowest reading was 3 lbs 4.7 oz.
The Timney mechanical gauge averaged 3 lbs 7.5 oz. Each mark, on the scale, is 2 oz and is possible to read to 1 ounce. The highest reading was 3 lbs 10 oz. The lowest reading was 3 lbs 4 oz.
Unfortunately, the guy that owned the Wheeler Digital, dropped the unit and could not get it to turn on. This was a disappointment.
I'm not saying all units will work as close as these and your mileage might vary. Also, durability of each unit is unknown.
