Lusting after an H&K

Skarekrow88 said:
"Magazine springs are not weakened by compression" is a bit of an absolutist statement if you ask me.

While I do acknowledge that compression and decompression cycles weaken springs much more substantially than just leaving them compressed, I have found in my experience that leaving certain magazine springs compressed does in fact weaken them to some degree. My HK USP magazines being the most effected by being left fully loaded of all my other pistols. My theory is that the metallurgy or heat treatment of the USP springs I had were sub-par. I have many other magazine for other guns that I have left loaded for just as long if not longer and they dont seem to be weakened anywhere near as much as my USP magazines were.

I watched a video by Paul Harrell where either he, or a friend, bought a Browning A5 or similar type shotgun that had been left in a closet for a multitude of years with the bolt locked open. When they went to test fire the gun it had consistent failure-to-feed problems due to the recoil spring being weakened from being compressed for that length of time. The issue was remedied by replacing the recoil spring if I remember correctly.

I wouldn't say that it is universal but I am of the opinion that its certainly possible/plausible that leaving some springs (depending on their quality) compressed can weaken them albeit not as much as a high amount of compression/decompression cycles will.
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Unless you have some new physics or metallurgical research of which I am unaware, your “sense” of your compressed springs weakening is Poppycock brother. Given the properties of metallic atomic bonds it is neither possible nor probable. How did you measure the weakening btw?

I am a big Paul Harrell fan but he is dead wrong on this score.
 
How did you measure the weakening btw?
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Got some new mags.

Disassembled the mags, compressed the springs to a specific length and measured the force required.

Reassembled the mags, loaded some fully, left some unloaded, loaded some partially and left them all for several months.

Then I repeated the disassembly, compression and measurement and looked at the difference.

I also found that underloading a mag by a couple of rounds and leaving it that way for a long time resulted in measurably less weakening than loading them fully and leaving it for the same period. Seems like the last little bit of compression made the biggest difference--at least in the mags I tested.

I ran one of these tests for years and found that although the weakening rate decreased over time, it was still possible to see additional weakening taking place as the test progressed.

A really quick (but not nearly as precise method) is to measure the change in the length of the uncompressed spring since a spring's force is related to the compression distance. As the uncompressed length of a spring decreases, therefore its force must also decrease.

It's not a complicated experiment--but it's the opposite of instant gratification.
Unless you have some new physics or metallurgical research of which I am unaware, your “sense” of your compressed springs weakening is Poppycock brother.
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I think this is the same type of thing as the physics behind "All things fall at the same speed." They do in a vacuum, but in the real world, air resistance comes into play.

Same with springs. Maybe in the ideal case, springs that are made perfectly, heat-treated perfectly, in a design that doesn't over-compress them never weaken from compression alone. But in the real world, where things are less than perfect things are different.

I posted the results from one of my earliest tests on a couple of mags probably 6 or 7 years ago. I kept doing them but stopped posting the results because it was pointless. I came to the conclusion that when it comes to this topic people want to believe what they want to believe more than they want to know the truth.
 
I grew up around spring piston air rifles and manufacturers like Weihrauch and RWS recommended not to leave the air gun cocked in order to avoid the springs to set.

The internet has experts springing up that know much more than the dumb German engineers, just like the fairy tale not to shoot lead through polygonal rifling. Incidentally, HK had even given reloading advice for the HK P9S with LRN and LTC bullets and I have the letter. Those loads had been tested by Pixa and that he can shoot cannot be questioned.
 
I grew up around spring piston air rifles and manufacturers like Weihrauch and RWS recommended not to leave the air gun cocked in order to avoid the springs to set.
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Yup. In his book on the Beeman R1, Tom Gaylord recorded the results of a test he did on various spring-piston airgun springs where he left them compressed for long periods and then recorded the resulting velocities. They weakened from being left compressed and the longer they were under constant load, the weaker they got.
 
Did the OP/ Prof. Young ever buy that HK .45 in his photo, or another USP?

PzGren: I enjoyed your comment (# 63) that some Internet Experts know much more than dumb German engineers.

Some of those same types of people on rifle forums seem to be as well-trained in guns and tactics as our military special ops/forces.
 
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