Question for Gunsmiths

[LHB1]

When I use a Lyman digital trigger pull gauge to measure trigger pulls on my 1911's (four Wilsons and one Kimber), I see a difference in weight depending on method used. If I just cock the hammer, the pull may read 3 lb 5 oz but if I rack the slide the trigger pull will read 3 lb 10 oz. The readings are consistent within +/-1 oz or so and apply to all five 1911's. I normally consider the pull weight measured by slide racking method as the true trigger pull since that is what happens when firing the gun.

Question: What causes the difference in weight of pull?

Thanks for info.
LB

 

[brickeyee]

Most likely differences in how far the hammer was actually cocked and the sear/hammer engagement produced.

 

[Jim K]

When the slide is racked, the hammer is dropped on the sear rather than the sear just moving into the hammer notch. That forces the two parts together and causes a tiny bit more friction. Try this. Cock the hammer, then pull it back and let it drop on the sear a couple of times. I think the trigger pull will be higher than if you just slowly cock the hammer. If possible, you could also try the trigger pull after actually firing a round (load one round in the magazine, chamber the round, remove the magazine, and fire. Then measure the trigger pull.). The pull will be at the higher level.

Don't worry about dropping that hammer on the sear. I saw a man go berserk when he saw someone do that, but it is nothing compared to what happens when the gun fires.

Jim

 

[Onmilo]

I have found that the Chinese made Lyman digital trigger pull guage is not at all accurate.
It will give you a rough idea of the pull weight and not much else.
I use two British made recording trigger pull guages in the shop, a six pounder for rifle and single action handgun and a twenty five pounder for everything else. These guages are actually British Postal scales and very high quality.
Our range uses an official NRA drop weight manual guage set.
None of these manual pull guages are cheap, my pair cost about two hundred bucks but if you really want to know exactly what your firearm pull weight is then these are the only way to go.