Changing hammer springs in pistols?

[Mike P. Wagner]

I am very close - I think to picking up a Beretta PX4 - probably full size because I am not very interested in carry.

I plan to shoot it stock for a long time - figuring the weak link the chain will very likely be me for quite a while.

But I have been reading. :-)

One of the comments I have read - about nearly every pistol, not just the PX4 - is a recommendation to improve the trigger by replacing the hammer spring with a lighter spring.

I know nothing abut mechanical engineering - but my background in software engineering has taught me that almost every engineering decision is a tradeoff - there is almost never a free lunch.

The question I have is, "What tradeoff are you making when you go to a lighter hammer spring?"

If a lighter hammer spring almost always improve the trigger, why don't Beretta - and other engineers - just call for a lighter hammer spring straight from the factory?

[Aguila Blanca]

There are at least two potential negative consequences:

1. Slower hammer speed ("lock time"). This is subtle, and generally only a concern for world-class target shooters
2. Light strikes may not set off cartridges with hard primers.

[JohnKSa]

Advantages:
A lighter hammer spring will:

• Make the DA trigger noticeably lighter.
• Make a slight improvement in the SA trigger, but that may not be noticeable.
• Make the hammer easier to cock. Not many people thumb-cock autopistols--just listing this to be thorough
• Make the slide easier to rack since part of the action of the slide is to cock the hammer.

Disadvantages:
A lighter hammer spring will:

• Make the hammer fall less energetic. As already mentioned, that can potentially cause misfires. It's important to note that the hammer fall in DA is usually shorter (and therefore less energetic) so if a spring replacement is done, the gun needs to be tested primarily shooting DA to ensure reliability.
• Increase slide velocity. One of the first actions of the slide is to cock the hammer. With the hammer easier to cock, that means that the slide will not expend as much energy in the operation and therefore it will be moving faster on the rearward travel. This could potentially cause more wear and tear on parts since ultimately something is going to have to stop the slide and that means an impact. Higher velocity means a more energetic impact.
• As already mentioned, the lock time will be increased. Lock time with rifles is probably more of an issue than with pistols, but it is a potential disadvantage and should be listed.

[wild cat mccane]

Someone probably said it better than me.

But when I changed my P2000 spring, people cautioned in HK, but strangely never mentioned in CZ Cajun Gunworks, that a lighter main spring from stock to Wolff 10 or 11 lbs will decrease pistol longevity.

Too light and rounds won't fire.

[Jim Watson]

I think factory springs are meant to allow for "taking a set" with long use and overcoming the friction and misalignment of parts on the edges of tolerance.

A competitor will typically have a gun either selected or refitted for easy operation and he will service his guns regularly. Springs are cheap. Joe Blow and Officer Grouchy may not be so thorough.

[wild cat mccane]

It wasn't that those lighter spring need more replacement intervals, it was that the lighter spring themselves increases battery.

It's an odd one, because it comes up with HK all the time, but never comes up with people mention they replaced their CZ P07/09 springs.

[wild cat mccane]

Nope. I take that back.

I was advised the spring life goes down on lighter springs and thus the increase of battery goes up if you don't change more frequent. On the HK it was spring life of 20K to something less on less than stock.

[Jim Watson]

It wasn't that those lighter spring need more replacement intervals,

There were folks reporting extra light Beretta mainspring life of 3000 rounds before misfires set in.

[chris in va]

I think one main reason not mentioned yet is due to having a balance between trigger feel and unintended discharges from a too-light trigger pull, especially for 'service' pistols. The average seems to hover around 5.5#, but many hammer fired full size pistols have a DA/SA pull so the operator has to REALLY be sure they want to fire at that target under duress.

[wild cat mccane]

Decocked, a CZ p07/09, PX4, Sig 2022, and HK are in no way even close to light on double action.

I feel that my P99 and Sig P226 Elite have the lightest double action I've felt, and they are still "heavy." Just much cleaner than others.

I am pretty sure the PX4 Competition Trigger Group only reduces single action.

Main hammer spring is double action only. Without cam, the trigger doesn't pull back the hammer on single action.

[Nathan]

First, there is no good use case for a DA/SA pistol. I’m sorry, but that needed said.

That said, a 10 lb DA trigger is quite shootable IME. Transitioning to the SA, well, that is on you to figure out and it won’t be easy.

Lightening the DA is usually an effort to narrow the DA to SA gap. Why not just try a striker fired gun?

Are there any PX4 specialists? If so, call them.

[wild cat mccane]

I think there are two:

1.no dead trigger on a sa/da,
2. a sa/da with decocker removes the requirement for a safety on a single action, though we've seemed to given those up with strikers that are 100% cocked.

Most SA/DA triggers, can't think of any, are not less safe than a fully cocked striker, as all have pre types have pre travel and a 100% sear/hammer. Glock is the loner for not being 100% cocked?

So restrike is a benefit for sure. The P99 copy Canik TP9/TP9SF sure was popular for a while.

[JohnKSa]

I haven't made a study of how many guns have a partially cocked striker, but there are some out there other than Glock. The FN striker guns I've looked at have a partially cocked striker as do the Kahr guns. As I recall, the FN pre-loading is similar to Glock's, but Kahr has more pre-loading than Glock but I could be wrong as I'm not looking at numbers, just trying to go from memory.

1.no dead trigger on a sa/da,

Right. A true DA gun will allow a restrike if something goes wrong whereas most striker guns will require that the slide be cycled to reset the trigger if there's an issue. It's not that common to need this function, but there is something comforting about knowing that you will always be able to pull the trigger and get full function out of the gun.

[wild cat mccane]

*any relevant guns

[TunnelRat]

I have swapped hammer springs on SIGs, HKs, CZs, Beretta 92s, and probably something I am forgetting. I have been able to get good reliability from the results, but you want to test it with whatever ammunition you plan to use. A while back I had a lot of Norma that saw me getting light strikes. I went to a heavier hammer spring because I thought I had gone too far. Then I also got light strikes with a Glock and realized it was the ammunition.

Besides the lighter spring that Beretta sells, Langdon Tactical sells their own as well, in two different spring weights:

https://langdontactical.com/px4-chro...hammer-spring/

[wild cat mccane]

When it gets time to do it, they are very easy. I did a P09 main spring change and TunnelRat calmed my nerves on the HK P2000 main spring change.

Don't expect a different gun. That is for sure.

[44caliberkid]

I would leave it alone, especially for just recreational shooting. The factory picks the spring for long service life and to reliably ignite primers from any manufacturer. I never use the DA function on DA/SA pistols, except maybe once or twice when new, just to see how it goes. At the range, when I chamber a round, it’s cocked. For carry, I go cocked and locked. I have never replaced a hammer spring in any pistol or revolver, except for trying a lighter hammer spring in a SAA, which resulted in light hammer strikes and misfires. I changed back to the factory spring immediately. I have put lighter trigger return springs in S&W and Taurus revolvers. My 40 year old 1911 that I use for bullseye target competition, guessing around 40,000 rounds fired, still has the original hammer spring that came in it.

[TunnelRat]

Originally Posted by 44caliberkid

I would leave it alone, especially for just recreational shooting. The factory picks the spring for long service life and to reliably ignite primers from any manufacturer. I never use the DA function on DA/SA pistols, except maybe once or twice when new, just to see how it goes. At the range, when I chamber a round, it’s cocked. For carry, I go cocked and locked. I have never replaced a hammer spring in any pistol or revolver, except for trying a lighter hammer spring in a SAA, which resulted in light hammer strikes and misfires. I changed back to the factory spring immediately. I have put lighter trigger return springs in S&W and Taurus revolvers. My 40 year old 1911 that I use for bullseye target competition, guessing around 40,000 rounds fired, still has the original hammer spring that came in it.

Not every DA/SA pistol can go cocked and locked, including the OP’s PX4.

[wild cat mccane]

Here the "G" model with decocker on the PX4 is less common. You really have to search out the G model.

The safety DA/SA PX4 is the more common model

[Tool]

Guess I'm an outlier. I want the triggers on all my guns to be tighter. My favorite guns so far are the rim-fired revolvers. Those tight triggers are intoxicating to me

[TunnelRat]

Originally Posted by wild cat mccane

Here the "G" model with decocker on the PX4 is less common. You really have to search out the G model.

The safety DA/SA PX4 is the more common model

You can’t go cocked and locked with the PX4, even with the safety model though. You can convert a safety mode to the G variant.

https://youtu.be/GWc6i506oEQ?si=FkWxHDdpPNzhPx3u

You can also buy replacement levers that are smaller in profile. I like these over the stealth options.

https://langdontactical.com/px4-carr...cocking-lever/

[wild cat mccane]

Oh, does the standard safety drop the hammer? interesting. Thanks!

[TunnelRat]

Originally Posted by wild cat mccane

Oh, does the standard safety drop the hammer? interesting. Thanks!

The safety on the PX4 works like the safety on the standard 92. You decock the pistol and it is on safe, so the hammer is down and the trigger is “disabled”. If you then flick the safety off, the pistol is in DA. I would rather just have a DA.

With the conversion video above you’re just removing parts, you don’t actually need to buy parts. In full disclosure, I haven’t done that myself. I did buy and install the G model conversion for a standard Beretta 92.

[Aguila Blanca]

Originally Posted by Tool

Guess I'm an outlier. I want the triggers on all my guns to be tighter. My favorite guns so far are the rim-fired revolvers. Those tight triggers are intoxicating to me

What does "tighter" mean in regard to a firearm trigger?

Lighter? Heavier? Shorter? Longer?

[Tool]

Originally Posted by Aguila Blanca

What does "tighter" mean in regard to a firearm trigger?

Lighter? Heavier? Shorter? Longer?

Heavier. My fingers need some workout anyway

Folks, which in production pistol has the heaviest trigger?