Magazine spring questions

[kdmoore]

The previous poll has me wondering about some things.

Guyon mentioned some engineer friends that claim with current materials springs don't "take a set" if you leave your mags loaded.

I have wondered about this very thing as well, but I don't have any materials engineers to ask. But I CAN tell you this much, Mag springs do seem to relax over time. Some 17 rounders (South african, for my BHP) where so stiff I could only get 15 or 16 rounds in without using a mag loader. I filled them up, put them in the safe and came back a week or so later. No more problems!

I bought one (cheapo) 30 rnd mag for range play. I tested it when new and it worked fine. I left it loaded for a month or so and when I shot with it again things have changed. Now it is a jammer for the first 10 rounds.
I'm talking FTF's, Nosedivers!
I'm convinced that the spring is the culprit (haven't changed my factory ammo type, gun works perfectly with my various 8 other mags, but did change the recoil spring from 17 to 18.5 as many bhp owners do)

All of this is mute if your gun is for self-defense and/or you have a ready supply of replacement springs.

But some may have more rare mags. Others may just be curious. Can anyone take a shot (I just love saying that) at answering the following?

How different are the materials that modern mag springs are made of?

Can they weaken to the point of non functioning? or is my experience just another strike against cheapo mags?

I just ordered a Star Super Model B pistol. Not sure exactly when made and won't know till I see the serial number, but should I worry about spring life with it?

Thanks in advance. Nice to be able to draw on the vast experience of this board!

-K

 

[Mark IV Series 80]

I read an article written by an aerospace engineer on this subject some years back.

IIRC, after doing some tests and calculations, he advised loading the double-column magazines to 90% of their capacity.

He noted that the high quality, single-column magazines did not experience reliability problems when kept loaded for extended periods of time.


Wolf Gunsprings has a good selection of springs:

http://www.gunsprings.com/SemiAuto/StarNF.html#StarLargo

-Mk.IV

 

[Mark IV Series 80]

How different are the materials that modern mag springs are made of?

I don't know which materials are being used by the various manufacturers, but here are some commonly used spring materials:


HIGH CARBON STEEL

Music Wire: Very high tensile strength. uniform properties. Readily available in nearly all sizes. Maximum service temperature of 250 deg F.

Oil Tempered Wire: Excellent straightness characteristics. Good selection of sizes, especially over .250”. Less expensive than music wire in large quantity. Maximum service temperature of 300 deg. F.

Hard Drawn HDMB Wire: Lower cost than music and oil tempered wire. Maximum service temperature of 250 deg. F.

STAINLESS STEEL

Type 302: Extensively used for spring manufacture. Available in a wide variety of sizes. Good corrosion resistance. Magnetic in spring temper. Maximum service temperature of 600 deg. F.

Type 17-7 PH: Excellent high tensile qualities after age hardening. Good corrosion resistance. Maximum service temperature of 700 deg F. EXPENSIVE, and has relatively high Quality Problems.

COPPER BASE ALLOYS

Phosphor Bronze: Good electrical conductor. Good corrosion resistance. Relatively low tensile strength compared to steel wires. Maximum service temperature of 200 deg F.

Beryllium Copper: Good electrical conductor. Age hardening required to improve tensile strength. Unstable during hardening makes tolerances difficult to hold. EXPENSIVE. Maximum service temperature of 400 deg. F.

NICKEL BASE ALLOYS

Inconel X750: Non-Magnetic. For High temperature applications. Relatively low tensile strength after age hardening. EXPENSIVE. Maximum service temperature of 1100 deg F.

This company has a nice chart for spring material properties:

http://www.acewirespring.com/pages/tech.html

 

[4thHorseman]

I don't know about all this scientific modern metals and stuff, but I can tell my mag springs took a set and jammed the gun like crazy until finally tried new mags. I could of just changed springs, but I didn't. Now I rotate the mags every week so I don't have this problem again.