By Mike Watkins
The Gang here at Brownells were recently discussing spring set on new magazines springs and 1911 Colt type pistols. I decided to do a comparison test on AR-15 20 round magazines springs and 1911 recoil springs.
The test was done to compare Chrome Silicon springs, Stainless Steel springs, and Music Wire springs. This would be a Gunsmith test only, since we don’t have a full laboratory with precision testing equipment. The test was to measure the new length of each magazine spring, and then load up the mag with dummy rounds to full capacity. The final step was to check the length of the springs after three days and ten days to see how much shorter the springs were, or how much set the springs took.
On the recoil springs for the 1911, I measured the new length of a Chrome Silicon spring and a Music Wire spring. Then I cycled the slide on the gun fifty times to compress the spring in its travel as it would cycle in firing the gun. I then measured each spring to see how much set it took.
There are different opinions on what spring material is best. Chrome Silicon springs are said to have less set initially and during their life cycle and thus give greater life.
Stainless Steel of course is more rust resistant for Military use or severe conditions.
Both can be heat treated, shot peened, and stress relieved after forming to increase spring life and function. The stress relieve temperatures are normally 800 to 825 degrees, as Chrome Silicon springs can withstand temperatures of 1300 degrees maximum. This is far more than what is required in most firearms.
Music Wire springs have good tensile properties and good corrosion resistance. They also have an operating temperature of around 250 degrees, but can be affected by 175 degree temperatures. Music Wire springs have been the standard of the industry for years due to the toughness of the material.
The chart below will show the results of how much each spring set during compression in the magazine or during cycling in a 1911 Auto.
| SPRING SET TEST RESULTS |
AR-15 Magazines |
| 20 Round Curved Magazine |
New |
3 Days |
10 Days |
| Chrome Silicon Spring |
8.464 |
8.425 |
8.425 |
| 078-000-106 |
- |
- |
- |
| Set |
- |
0.039 |
0.039 |
| |
| Stainless Steel Spring |
7.362 |
7.283 |
7.238 |
| 078-000-132 |
- |
- |
- |
| Set |
- |
- |
- |
| |
| 20 Round Straight Magazine |
- |
- |
- |
| Music Wire Spring |
7.362 |
7.283 |
7.283 |
| Set |
- |
0.079 |
0.079 |
1911 Recoil Spring 16lbs |
| - |
New |
After 50 Cycles |
- |
| Chrome Silicon |
6.456 |
6.299 |
- |
| Set |
|
0.157 |
- |
| |
| Music Wire |
6.692 |
6.496 |
|
| Set |
|
0.196 |
|
I was surprised that the springs set in such a small amount between the different spring materials. Understandably, the test performed is not at all conclusive to the results one would find through shooting over a longer period of time.
The fact that all springs take an initial set is true and continue to do so over time as long as the same load or compression is the same. I did measure an old Colt AR-15 magazine spring from about 1972, which was the original and it measured 7.086 inches long. I also have a 70 series Colt 1911 from 1975 with the original recoil spring in it which measured 6.338 inches long.
Not a lab quality test by any means, but the results are interesting.
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