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does keeping gun in half-cocked position accelerate wear??

10K views 39 replies 12 participants last post by  NonConformist 
#1 ·
My apologies if this is an extremely silly question. I am curious if keeping my USP in the half-cocked position will accelerate wear on the hammer spring?? I am kinda figuring it won't accelerate wear considering the fact that the gun always returns to half-cock when using the decocker. I just thought I would ask you guys to make sure?

When I am out and about I usually keep the gun cocked and locked with a round in the chamber. But when I am at home I keep it unloaded and since I have had the gun I have been lowering the hammer by hand, but if keeping the gun at half-cock does not accelerate wear on the hammer spring then I will just use the decocker from now on.
 
#4 ·
Constantly staying compressed will also weaken a spring.

In this case of keeping it half cocked, nothing to worry about. The hammer spring is barely compressed at all when in the partial cocked position. It is always smart to decock the gun with the decocker lever. Hammer springs are only about $5 from HK. I always keep a bunch of extra ones and replace them once a year on the guns that get carried or used as home defense. Same with the mag springs. Very small monetary and time investment to satisfy my OCD when it comes to reliable ignition on a defensive gun.
 
#22 ·
Is that really true?
How many studies have been done suggesting the opposite? (LOTS)
Think about your car... really heavy stuff, sitting on springs all the time. Having a car sit in the driveway will not wear out the shocks at all. It's going over bumps and driving the car that weakens them.
The thing about this whole issue is that the spring has to have the correct tension / strength to handle being compressed all the time. Same goes for magazine springs... keeping mags fully loaded, etc.
Loading and unloading mags wears them out, not leaving them loaded, springs compressed.
I think if the engineering of the springs is sound, they can be compressed the way they are supposed to be, virtually forever without any problems.

That whole issue aside, I think that storing a USP in the "decocked" position is far less detrimental to your gun than dry-firing it to fully lower the hammer.
 
#6 ·
While it's true that springs take a set if kept in a compressed state, it won't be enough to cause them to be unreliable if it was designed correctly. For example, with completely made up numbers, let's say it takes a 5 lb spring to reliably fire a primer, and it comes with a 15lb spring. If keeping it cocked for 20 years reduces the pressure to 12 lb, it won't matter. A new spring will take a set from either cycles or constant loading, then it will stay right at that spring constant until it fatigues and breaks due to many cycles. It won't continue to weaken under a static load once it takes that initial set.

I've got magazines I've kept fully loaded for over 20 years. They are emptied at the range, and I usually leave when I still have enough rounds left to refill all my magazines.
 
#7 ·
Dave,

If keeping a spring compressed for long periods of time doesn't weaken the spring then why does HK themselves tell you that if a LEM pistol is to be stored for a prolonged time (over a year) that you should ensure that it is unloaded and pull the trigger to release tension on the hammer spring. I know the LEM is pretty much like having a DA/SA hammer in the cocked position, with regard to the hammer spring compression, and is much different than what the OP asked about the half cock position, but I wanted to try and clear up these spring questions.

Even on Wolff Gunsprings website they state that a mag kept loaded will fatigue the spring over time and should be rotated with other mags or the mag spring should be replaced on a regular basis to ensure proper function. I know they are in the business to sell gunsprings but with the dealings that I've had with them they are not in the business of trying to over sell springs to rip people off.

I'm just too anal retentive to risk a malfunction with my home defense or CCW pistol because of a $7 spring. On a yearly basis I replace my hammer spring and magazine spring on my home defense USP 45 LEM.
Just my 2cents.
 
#8 ·
Dave,

If keeping a spring compressed for long periods of time doesn't weaken the spring then why does HK themselves tell you that if a LEM pistol is to be stored for a prolonged time (over a year) that you should ensure that it is unloaded and pull the trigger to release tension on the hammer spring. I know the LEM is pretty much like having a DA/SA hammer in the cocked position, with regard to the hammer spring compression, and is much different than what the OP asked about the half cock position, but I wanted to try and clear up these spring questions.

Even on Wolff Gunsprings website they state that a mag kept loaded will fatigue the spring over time and should be rotated with other mags or the mag spring should be replaced on a regular basis to ensure proper function. I know they are in the business to sell gunsprings but with the dealings that I've had with them they are not in the business of trying to over sell springs to rip people off.

I'm just too anal retentive to risk a malfunction with my home defense or CCW pistol because of a $7 spring. On a yearly basis I replace my hammer spring and magazine spring on my home defense USP 45 LEM.
Just my 2cents.

If you read it again, they actually state that 1911 magazines can be loaded for years at a time fully loaded. Then they state that downloading mags by 1 or 2 rounds will increase spring life. That's just 1 or 2 rounds, much less of a reduction than half-cocked. And that's what the OP asked - if the half cocked position will wear out the spring. And I think that it will not.

And I just looked over the manual for the LEM - much of the section on long term storage are for safety reasons, not spring life. They say to store it without a cartridge in the chamber, magazine, or storage container. It also says to store the ammo separately under lock and key.

And for the LEM specific portion, there's this caution:

"CAUTION: In the USP pistol fitted with LEM parts, clear the pistol and release pressure on the cocking piece and hammer spring by dry firing the pistol one time. Only then can the HK Lock-Out device be placed in the locked position on pistols fitted with the Lock-Out device (See page 28)."

That's not to increase spring life, it's a liability/safety issue.

So feel free to replace them if it makes you feel more confident, but all I know is that I have several guns that were my grandfather's, a few are approaching 90 years old, and several that are 50 years old. They all have original springs, and some have stayed loaded nearly the entire time except for the summer time when we would shoot them day after day.
 
#12 ·
It doesn't matter if they are double stack or not. Only a spring pressed past its limits (overloading a mag) will cause fast wear. Coming from the beretta world, I'll tell you that we've had this discussion several times. You don't need to change out a hammer spring yearly. Companies put that "advice" intheir official literature for the same reason that mcdonalds has to put "coffee is hot" on their cups... Ppl will sue for anything. Springs will wear, but it will take a lot of time or wear tomake it noticeable.
 
#14 · (Edited)
Glad you know more about magazine springs than Wolff does. I think everyone is misunderstanding what I'm saying. The hammer springs are probably fine left compressed for a very very long time. I have an OCD problem with my carry and home defense guns. For approx $2 a month and less than a minute of my time, I don't feel it's worth taking a chance with hammer and mag springs. Just my 2cents about that.
 
#13 ·
ptechjpjr -- I understand that's what your manual states. FWIW, the manuals aren't always written by folks with the deepest understanding of how the gun works or how it's supposed to be operated. For example, I think SIG still uses a photo of a "field stripped" P22x in its manuals that shows the recoil spring removed from the guide rod... even though end-users are not supposed to remove the spring from the guide rod, because you can actually put it back on the wrong way and affect reliability.

Why would it be bad to keep a stored LEM compressed, but it's perfectly OK to carry one loaded for years at a time?

It may very well be that decompressing the spring will add to its service life. I'm just skeptical that it's enough to matter.
 
#15 ·
Why would it be bad to keep a stored LEM compressed, but it's perfectly OK to carry one loaded for years at a time?

It may very well be that decompressing the spring will add to its service life. I'm just skeptical that it's enough to matter.
I doubt it matters either but like I stated in my above post, I have OCD about this and for $2 a month it's not worth causing worry inside my troubled little head.
 
#28 ·
Simple Science

Remember, when your magazine is fully loaded, your spring is not fully compressed. It is compressed a certain distance.
Think of a click pen. If you take the spring out, and tape it so that it remains fully compressed, and leave it for a long time, it might hurt the function of the spring.
However, just click the pen so that the tip of the pen is out, and leave it for a century.
The ink would dry up, but I'll bet the farm you would be able to click, click away, and the mechanism of the pen would function flawlessly.
 
#29 ·
Wow. Lots of great knowledge gained from this thread. Thanks a lot guys! I never lower the hammer by hand with a round in the pipe. That is just a terrible idea. Whenever I lower the hammer by hand I make sure there is no round in the chamber and that the magazine is out. But now I will just use the decocker to save my thumb some soreness. I will just probably get some spare hammer springs in case of any hiccups.

I am an ex-1911 guy so I am still getting used to all this new tupperware ;) ;). Haha. I must say though that so far I love the USP much more than my 1911 from a practical perspective. It is just not as pretty as a well modified 1911. It is close though!
 
#30 ·
Dannyboy,

My mag springs were not causing malfunctions other than not locking the slide back. In my mind (as troubled by OCD as it is) this meant that a malfunction might not be too far away. I know it is not either one of my thumbs hitting the slide release lever because I don't hold my weak hand thumb that high and my strong hand thumb is not long enough to hit the lever on my USP 45. On my P2000 it is sometimes a different story. Even with brand new Wolff mag springs sometimes my slide wont lock back, but I know that it is my strong side thumb riding the slide release, because it can reach it on the P2000. My OCD is not strong enough to cause internal issues in my head if I know that I was the reason for the slide not locking. Like you said I also don't think that the slide not locking back is even a malfunction, but I do believe that if the mag spring is not strong enough to raise the slide release lever, it is not too far away for a real malfunction to occur. This could even be more critical with the high powered defensive ammo that I'm sure we all use. Be safe and let's all just enjoy our HK's.
 
#31 ·
I think AD hit the nail on the head here, folks.

There is a difference between having an effect and having a meaningful effect. A new spring may be longer than an old/used spring, but that doesn't mean the old/used spring is defective.

Think of it in terms of the tire tread on your car. Do you replace your tires as soon as there has been 1mm of tread loss? No. You replace them when the tread reaches a point at which the tires no longer have a high confidence of performing their job.

Having the mainspring (hammer spring) compressed for years at a time may in fact lead to a shorter service life for the spring in an absolute sense. But I doubt it plays enough of a role to matter under any normal circumstance.

On the other hand, if ptechjpjr wants to change his mag springs every third Tuesday, who the heck cares? That's his business. Is it overkill? Of course. Is he hurting his guns? No. Is he hurting your gun? No. I say we wash our hands of this whole thread. (ptechjpjr will need to wash his hands ten times, of course :cool:)
 
#38 ·
I think AD hit the nail on the head here, folks.

There is a difference between having an effect and having a meaningful effect. A new spring may be longer than an old/used spring, but that doesn't mean the old/used spring is defective.............

+1

My take on this whole thing: If it truly made a meaningful change in your spring the manufacturers would ask you to disassemble the firearm every chance you got to unload the compression/tension on all of the springs........not just hammer springs, but recoil springs, mag springs, etc. and you would have a spring replacements schedule in the documents as well.
 
#33 ·
Thanks for the spring tension discussion. I think most of us forum surfers do our learning by just listening in on the conversations of well informed people like you. I am sure that many of the forum readers are familiar with the subject of "springs", but many of us are not. So, please keep kicking these things around because a lot of people are benefitting from them.
 
#34 ·
There is actually one thing that could make changing out springs yearly a bad idea. Occasionally, a spring mfg may get some bad spring stock material. If you are constantly changing out springs, the likelyhood of at some point installing a bad one is greatly multiplied. I'd much rather rely on a set of springs that has seen some use and has been proven than a brand new untested set all the time.

Case in point - a typical car engine valve spring, in 100,000 miles, may see 200,000,000 cycles - that's Two Hundred MILLION for those of you keeping score at home. And that's assuming an average speed of just 30 mph. They may see twice that many cycles. And when the engines aren't running, at least two of those springs is kept at a constant full compression. Will they be shorter/weaker than brand new springs after 200 million cycles? Yep, they absolutely will be. But they still have enough tension to properly seat the valves.

However - the last LT1 I built, I used a brand new set of springs because I needed some that could take more lift and at higher pressures than factory springs due to the cam I was using. The first one fatigued (i.e. broke) at 15,000 miles. I bought a single replacement. The second one broke 5,000 miles later, I replaced just that one. When the 3rd one broke 3,000 miles later I knew there was a problem. The mfg found a problem with that batch of springs, sent me an entire new set, and they've been there for 30,000 or so miles now with no failures. In that case, it wasn't the material, there was some unseen wear on their tooling that was putting a tiny indentation on the spring which created a stress riser.

If you constantly replace tested springs with untested (brand new) ones, you may at some point replace a perfectly good spring with one destined to fail.
 
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