Two-stage triggers

[TwoRivers]

The two-stage trigger originated with bolt action military striker-fired rifles (Mauser) as a safety feature. In these rifles the firing pin is blocked by a vertically rising sear connected to the trigger, which withdraws the sear downward, out of the way of the firing pin. By providing a two-stage trigger pull adequate engagement for safety, and a lighter final let-offd are provided. This is accomplished by two camming humps on the trigger arm; the first drawing the sear down to almost let-off, with the second allowing the firing pin to fall with a lighter short pull.

Where other then bolt action rifles have a two-stage trigger, it again is a safety feature, though it does not affect sear engagement. Here the first pull is simply against light spring pressure. In modern bolt action trigger designs an over-ride design is used, with the sear pivoted horizontally, and propped up by a vertical trigger arm. When this arm is withdrawn from beneath the sear, the firing pin over-rides the sear through the pressure of the firing pin spring. Here again a two-stage pull would have the first stage against a light spring only, not affecting sear engagement. It is found on target rifles, where better control over let-off is desired, not on hunting rifles.

It is generally considered that the two-stage trigger is better suited to deliberate shooting, the single-stage being better for snap-shooting.

[aadhaulya]

So am I correct in assuming that the basic function of the two stage trigger and the trigger pull adjustment function are similar from a practical point of view??
Probably the difference being that the trigger pull adjustment has multiple stages.

Atul

[TwoRivers]

Not really. The typical military two-stage trigger will usually have around a 7-8 pound first stage, and 4-5 lb. pull-off. Whereas an adjustable trigger will be safely adjustable in the 2-5 lb. range, without stages.

[ckkalyan]

Nice explanation TwoRivers, thank you.

aadhaulya you might want to look at this article which explains a few basics about triggers and trigger pull. I recall your question about double set triggers on another post.

http://www.chuckhawks.com/trigger_pull.htm

Most triggers on sporting and target rifles and handguns today are single stage triggers. These ideally have no movement before releasing at their set weight, and when they fire they move only far enough rearward to release the sear. Such a trigger is a great asset to achieving a surprise break. The feel of a perfect single stage trigger is often compared to that of breaking a glass rod. Most triggers supplied on brand new guns today are single stage triggers, but are not properly adjusted.

A second type of trigger mechanism is the two stage trigger. This is common on military rifles and is supposed to be safer than a good single stage trigger. (Real firearms safety, of course, is between the ears of the shooter and has nothing to do with trigger type.) A two stage trigger has a long initial movement. The shooter pulls the trigger back to take up this slack until a sharply increased resistance is felt. (That is the first stage.) Then the actual surprise break trigger pull that will fire the rifle is begun, and from that point on the two stage trigger operates like a single stage trigger.

The third type of trigger mechanism is a wonderful little device called a "set trigger." This almost exclusively appears on older, expensive European, or reproduction black powder rifles. There are single set and double set triggers. The former is pushed forward to "set," and then pulled rearward to fire. The latter is simpler and more common. This consists of two triggers within the trigger guard of a single-barreled rifle, usually a bolt action or a single shot. (The Mannlicher-Schoenauer bolt action is perhaps the most famous example of a hunting rifle that is often seen with a double set trigger.) The trigger in front is the firing trigger while the one in back is the set trigger. Normally (un-set) the front trigger would have a trigger pull of about 4 pounds, and simply pulling the front trigger (although it may feel heavy and creepy) will fire the rifle. However, when one first pulls the rear set trigger back until it clicks, you have typically reduced the front trigger pull to less than half a pound. You must still pull the front trigger to fire the rifle, but after being set it is very light and clean.

[aadhaulya]

Nice explanation TwoRivers, thank you.

aadhaulya you might want to look at this article which explains a few basics about triggers and trigger pull. I recall your question about double set triggers on another post.

http://www.chuckhawks.com/trigger_pull.htm[/i]

This article makes it quite clear. But I think it may take me some time to absorb the information thoroughly. Thanks for the informative article.

Regards


Atul