Teach me about triggers...

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littleman77
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Joined: Fri Oct 10, 2008 5:08 pm

Teach me about triggers...

Post by littleman77 » Thu Dec 17, 2009 4:54 pm

In my self-directed (somewhat) firearms education I've developed a squishy understanding of trigger dynamics that may or may not be accurate. I think I "get" the following terms, but I'd like to read an expert description of: creep, stacking, overtravel, takeup, staging, "mush," and any other terms relevant to trigger "feel" that escape me at the moment.

I've handled and fired many guns, and can tell whether I like a trigger or not, but I lack the objective linguistics to adequately explain it.
Formerly known as Dr. Feelgood

MarkD
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Joined: Mon Aug 18, 2008 5:59 pm

Re: Teach me about triggers...

Post by MarkD » Thu Dec 17, 2009 9:35 pm

OK, I'll offer what I'm familiar with.

Creep is the movement of a trigger before it releases, when the trigger is engaged. Some triggers, especially military triggers, have some free travel in them before they engage, that's known as take-up. Take-up is OK, creep is not.

Over-travel is movement of the trigger after it releases, also generally not desirable.

Stacking I believe normally applies to double-action triggers (like on DA revolvers), it's when the trigger gets heavier as it approaches let-off. IIRC the Colt Python has a stacked trigger.

In general, a trigger should break like a thin glass rod, with no movement before or after let-off. Some triggers come closer to that ideal than others. Note that that has little to do with the weight of a trigger (the amount of pressure it takes to set it off), but with the felt motion of the trigger. Triggers with too much creep and/or over-travel feel mushy.

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Mike OTDP
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Re: Teach me about triggers...

Post by Mike OTDP » Thu Dec 17, 2009 9:40 pm

Let me try to explain this...

Triggers may have a wide variety of movements. When you pull a trigger, several things may happen. These include:

1. Movement of the trigger to engage the sear and take up all mechanical slack in the trigger linkages. This is "takeup".

2. Movement of the trigger to partially release the sear. This is the first stage of a two-stage trigger. Not all triggers are two-stage triggers. The purpose of a two-stage trigger is to make a heavy (relatively) trigger seem lighter. A properly designed two-stage trigger has a distinct "stop" in the trigger pull. The movement is sometimes called "staging".

3. Movement of the trigger to release the sear. This is present in all triggers. A trigger that has little movement is "crisp". A trigger that has movement, but releases smoothly, has a "rolling release". Triggers that have movement and do not release smoothly are "mushy" and have "creep". Double-action triggers that have a trigger pull that increases through the trigger movement arc have "stacking".

4. Movement of the trigger after sear release. This is "overtravel".

Hope this helps.

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