Single stage and roll over triggers

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buonvento
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Joined: Sat Nov 08, 2008 6:44 am
Location: Trani - Italy

Single stage and roll over triggers

Post by buonvento »

I've always used a two-stage trigger. Could you tell me the difference between a single stage and a rollover trigger?
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pilkguns
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Post by pilkguns »

A two stage trigger has a definite "stop" or "bump" or "hard spot" in its travel that allows you take up a certain percentage of weight and hold it before continung towards the breaking or release point where the gun fires.
some shooters prefer 50/50 some 60/40, some 75/25 but anymore than that gets dangerous for the shooter.

A single stage trigger has no such stop in it.

A roll trigger at the end of its travel, keeps moving as as the shoot is released. In essence the weight of the trigger at the end of its travel feels like it is getting lighter and lighter until it breaks.
In contrast to this a "crisp" trigger at the end of its travel, it seems like all the weight is there at once and then it is gone. Some refer to this as "lie breaking a glass rod" although I don't really know what this means, as I have never seen or heard of a glass rod, much less had much experience at breaking one.

using some rough estimates of percentages, lets say that your roll trigger has 90% of of its weight taken up at 90 % of the travel and the last 10% of both the weight and distance is still increasing.

A crisp trigger, maybe at 98% of its travel only has 85% of its weight applied. and the last 15% of weight is applied in that 2% of travel
peterz
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Glass rods

Post by peterz »

Back in my lab days I wasn't too bad with glass blowing. I've broken lots and lots of glass rods, most of the time intentionally.

That is exactly what a crisp trigger feels like when it breaks.

A glass rod is just that: a stick of glass, maybe 4.5 mm in diameter (or more or less), solid, and coming from the factory any where from maybe a foot to 3 feet long, again more or less and depending on what's ordered. Looks a bit like a clear plastic swizzle stick. You break it by nicking the rod with the corner of a file, then grabbing the ends and applying tension until the material fails right where the nick is. Glass tubes are the same but hollow.

But surely you knew all that.
peterz
Posts: 355
Joined: Sat Dec 05, 2009 11:31 am
Location: Great Falls, VA

Glass rods

Post by peterz »

Back in my lab days I wasn't too bad with glass blowing. I've broken lots and lots of glass rods, most of the time intentionally.

That is exactly what a crisp trigger feels like when it breaks.

A glass rod is just that: a stick of glass, maybe 4.5 mm in diameter (or more or less), solid, and coming from the factory any where from maybe a foot to 3 feet long, again more or less and depending on what's ordered. Looks a bit like a clear plastic swizzle stick. You break it by nicking the rod with the corner of a file, then grabbing the ends and applying ressure until the material fails right where the nick is. Glass tubes are the same but hollow.

But surely you knew all that.
Last edited by peterz on Mon May 30, 2011 4:05 pm, edited 1 time in total.
scerir
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Location: Rome - Italy

Re: Single stage and roll over triggers

Post by scerir »

It is possible that, in case of a crisp trigger, the action of the finger on the trigger tongue is isometric (an isometric contraction of a muscle generates force without changing length, that is to say the muscle contracts but does not shorten, giving no movement).

It is possible that in case of a roll trigger the action is isotonic (in an isotonic contraction, tension remains unchanged and the muscle's length changes, that is to say the muscle contracts and shortens, giving movement).
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RandomShotz
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Post by RandomShotz »

scerir wrote:It is possible that in case of a roll trigger the action is isotonic (in an isotonic contraction, tension remains unchanged and the muscle's length changes, that is to say the muscle contracts and shortens, giving movement).
pilkguns wrote:A roll trigger at the end of its travel, keeps moving as as the shoot is released. In essence the weight of the trigger at the end of its travel feels like it is getting lighter and lighter until it breaks
So which is it? I would think a good gun smith could arrange it either way. Firing a crisp trigger, 1 or 2 stage, is accomplished by smoothly increasing the force on the trigger until it breaks (I've been told). If the force required for the roll trigger falls off as it travels through release, does the shooter modulate the force or does the trigger simply accelerate?

I have read that the roll trigger is very difficult to master. As a beginner with FP and 10M AP, both with crisp triggersI have found the discipline to increase finger pressure and pull through smoothly difficult. I have to fight the temptation to hold a bit if the sight picture drifts. How does learning the roll trigger differ?

I know, I'm sitting here asking questions when I should be practicing ...

Roger

Oh, and I've broken a few glass rods too. Some intentionally ...
GaryN
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Location: California

Post by GaryN »

I was one of those "brainwashed" into thinking that a crisp trigger was the "best" trigger.

But, I now shoot my match AP and AR with "rolling" triggers.

My AP is setup as a 2 stage w the overtravel adjusted so there is just a little bit of trigger movement after the sear releases. I originally set it up for no overtravel restriction but I was pulling the shot. Putting the overtravel restriction fixed that.
When I got the AP it was setup for single stage no restriction on overtravel.

My AR is setup as 2 stage w/o any restriction on overtravel.

My 22 target pistol has a "crisp" trigger with overtravel restriction.

I have not bothered to try to see if any of the non-rolling triggers could be converted. The 22 is a very old High Standard, so I don't even know if it can be adjusted to have a rolling trigger. I rather doubt it. But using the 3 triggers works for me.

My personal opinion is you get used to whatever system or systems you use. You just have to give it enough time so your body adjusts to it.
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