Weak Pietta Trigger Spring

[Smokefire]

I recently bought an 1858 RNMA trigger spring. It fits fine, but the spring has much less of an arch to it than another one I have, resulting in not enough spring tension to activate the trigger at either half or full cock.

Is this a part that is intended to be manually adjusted to the pistol, or should they come bent enough to cause correct tension? I could easily bend it gently around the horn of my anvil, but I don’t want to break it if it’s more or less tempered to hold its current shape.

 

[Phil Coffins]

Generally the spring will come ready to use, if you bend it a tiny bit it may improve the action but I would much prefer the spring to be correct to start with.

 

[Jappo]

If the bolt is working good, check the length of the trigger spring part. Sometimes they are too long and keep the trigger from working as its supposed to.
The chance of breaking by bending are 50-50.

 

[ZUG]

Changing the arch of the spring leg may change its reach to the trigger. Check and see if the trigger spring leg is hanging up on anything.

 

[M. De Land]

I recently bought an 1858 RNMA trigger spring. It fits fine, but the spring has much less of an arch to it than another one I have, resulting in not enough spring tension to activate the trigger at either half or full cock.

Is this a part that is intended to be manually adjusted to the pistol, or should they come bent enough to cause correct tension? I could easily bend it gently around the horn of my anvil, but I don’t want to break it if it’s more or less tempered to hold its current shape.

Most factory bolt/trigger springs are much heavier than they need to be. I make my own and they are a good deal lighter than are the factory springs that don't often last very long.
Yes, to gradual of a bend can make the trigger spring to long and jamb against it and interfere with the tension.
Springs are all heat treated and temper drawn for strength and longevity.
Pictured is the bolt/trigger spring and wedge I make from stainless flat spring stock and A-2 tool steel. Note how much thinner the spring is compared to the factory offering at the top and left side are .
I suspect the reason for the heavy bolt spring is to dampen cylinder inertia into lock up and the trigger spring still will work reliably with much more tension than it ever needs to reset.

 

[Smokefire]

Well, I ended up annealing the spring I had and then I gently put it little more bend it to match another spring that was working well. Rehardened it, and then tempered it back to a light shade of purple-blue. Luckily, it held the bending through hardening and tempering and now it is working fine.

 

[Smokefire]

Most factory bolt/trigger springs are much heavier than they need to be. I make my own and they are a good deal lighter than are the factory springs that don't often last very long.
Yes, to gradual of a bend can make the trigger spring to long and jamb against it and interfere with the tension.
Springs are all heat treated and temper drawn for strength and longevity.
Pictured is the bolt/trigger spring and wedge I make from stainless flat spring stock and A-2 tool steel. Note how much thinner the spring is compared to the factory offering at the top and left side are .
I suspect the reason for the heavy bolt spring is to dampen cylinder inertia into lock up and the trigger spring still will work reliably with much more tension than it ever needs to reset.

You bring up some interesting points around bolt lock up.

I haven’t seen enough of these Pietta springs to say for sure, but it seems like the arch to the trigger side is a slightly softer arch, where about the last 3/32” of the bolt spring’s arch makes a more pronounced drop. I’m assuming the net effect of the shorter side of the spring (bolt side) with a more pronounced curve at the end produces much greater spring tension on the bolt that would be required to reset the trigger.

Looking at the trigger and hammer lock up positions, it does seem that the trigger reset should be sturdy enough to prevent slop, but not hard enough to interfere with cocking. Someday, I’d like to make a few springs myself and experiment with tempering the two leaves differently OR making a hybrid spring with a heavier bolt side leaf that would exert higher and more consistent pressure on the bolt to ensure tighter lockup.

Any idea what kind of steel should be used for springs like this?