Know what sets the trigger break weight on an M&P?

I have an M&Pf 9mm that has a trigger pull of 5.5 lbs, well, 5-1/8 lbs now that I installed the APEX DCAEK, but that's another thread - already posted in fact. My M&Pf .45ACP has an 8 lb trigger.

So as I installed the DCAEK in my 9mm, I looked to see why/how the two guns could have two different pull weights - simple, it's the springs, right? Negative, it isn't the springs it's the angle of the trigger bar ramp that operates the sear!

It's much like the way the Glock connectors change the trigger break weight. Obviously springs can change the weight as well, but the difference in my 5.5 lb and 8 lb trigger weights is because they have two different trigger bar ramp angles.

Yep - leverage (length of fulcrum...), and not spring rate.

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Originally Posted by gasmitty

Yep - leverage (length of fulcrum...), and not spring rate.

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I think we're saying the same thing but it's actually like a ramp, like pushing a load up a ramp.

You're right. Actually, I launched that without fulling engaging the brain; I should have stated "inclined plane," but in any event it's about geometry and not a spring rate.

So if you want to lighten the trigger weight, you'd need a different angled trigger bar ramp?

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Originally Posted by varob

So if you want to lighten the trigger weight, you'd need a different angled trigger bar ramp?

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Actually, you'd have to replace the entire trigger bar; the ramp is an integral part of the trigger bar. But to the question you asked, yes and no. If you are familar with the Glock connectors, the 5 lb and 3.5 lb, the difference is the angle of the small tab that the trigger bar strikes.

So if you have a 5 lb connector and replace it with a 3.5 lb connector, you will get a lighter trigger pull, but all the springs remain unchanged. The difference is the ramp, or even better as gassmitty put it, the inclined plane.

But for a competition only gun, one could replace the trigger spring and the striker spring with lighter springs and that too will decrease trigger pull weight. But I think most people just change out the connectors. BTW, the 5 lb connecter yields a shorter trigger pull than the 3.5 lb. The trigger bar has to travel further along the 3.5 lb ramp to get to the break point.

The same can be done with the M&P. E.g. my M&P .45ACP has an 8 lb pull and my M&P 9mm has a 6 lb pull. You can look at the ramps on the trigger bars and readily see that the ramp is 'steeper' on the 8 lb than the 6 lb. The same is also true about travel on the M&P. The trigger will break quicker with the 8 lb ramp, which makes one wonder that if he had an 8 lb trigger bar and replaced the trigger spring with a lighter one, one could get the shorter break and a lighter pull too. And the good news is that unlike replacing the springs in a Glock with lighter springs, installing lighter springs in the M&P doesn't affect primer strike energy. In a Glock it does - well, if you replace the striker spring.

I really like the trigger system in the M&P; it has a horrible reset, but the trigger allows interesting tweaks without worrying about light primer strikes. The only thing that really bothers me about the M&P trigger is the way the sear is mounted. It's enclosed somewhat snuggly in a three-sided box. If debris gets under the sear, and it can from the front, about the worst place for an opening, the debris could easily block the sear. In comparison, Arthur Viani, owner of Ghost Inc. shows a pic of a Glock connector and housing full of mud, and the Glock still fires.