testing 1911A1 Recoil Strength

03lover

How is the strength of 1911A1 and other semi auto recoil springs tested?

Since they are compression type springs, the testing device must compress the spring while a gage measures the weight in pounds. How much compression is required at some number of pounds to provide the correct number?

Does anyone know how this is done and if such a device is available for sale or can be fabricated?

I have seen some reference to the wire diameter being different and can be used to determine strength, but I have a number of Brownell's and Wolff springs and the wire diameter is not consistant with the the different spring ratings.

Once these springs are out of the envelope, they can difficult to impossible to know at a later date, what strength they are.

Any help will be appreciated.

rufe-snow

I've had the same problems, with the Wolff springs. Some of the other manufacturers recoil springs I purchased in the past have been partially painted to identify the spring strength, or have been made of square spring wire stock.

n/a

I'm not sure exactly how they test these springs, but I doubt that they are in a gun when they do test them.

More than likely they are in some sort of holder that then compresses the spring and takes a measurement of the force required to compress it.

JK

There is such a thing as a spring tester and it's used on all three types: compression, tension and leaf although the leaf has gone its way. Springs are not tested in a firearm unless it is stated as such in the manufacture. It's a pretty simple set up linked to a gage of the desired requirements. Most of the compressions are tested having a pin running down the ID while it is being compressed/tensioned so it won't corkscrew. Just about any manufacturer that winds springs has one
PS it's very interesting to put some of these springs on a tester and checking against what the manufacturer rates them in oz/lbs/etc. Most of these chinese imports do NOT check as stated by their manufacturer and some do not use the standard misic wire, causing them to fail from fatigue. I have encountered this dilemma many times

Tailgunner1954

Spring strength calculations have several factors, wire diameter, coil diameter, coil spacing and preload being among them.
The tester (I've rebuilt/calibrated a few of them) is basicly a force scale and a distance measuring device with a moving ram to provide the spring compression..

Hawk Carse

An engineer rates a spring on the force in pounds to deflect it an inch.
A gun maker rates a spring on the force in pounds to deflect it however far the gun's action does. A 1911 recoil spring will take about 16lbs to compress it to the full recoil position.

SDM makes a tester for the purpose, with marks and collar to set the compressed length. It uses a trigger pull gauge, so it is just balancing one spring against another. If you wanted a more precise reading, you could use weights or a calibrated gauge.
http://www.sdmfabricating.com/Tools/tools.htm

A convenient way to keep track of springs of the same appearance but different load ratings is by weight. Just take a new spring out of the package and weigh it on your powder scale. Then you can sort by weight as required. A pound of rating is 5-10 grains of spring wire mass. This really works only on springs of the same material and wind pattern, say Wolff Progressive.

perry shooter

Hello I made one using digital fish scale from Cabela's and a polished rod that was the same size diameter as recoil spring guide but about 12 inches long with one large bushing /stop that I can put in a vise and a nut and washer on other end . I marked the rod for full compression the length on a GOVERNMENT model and Commander and officers . I agree that many off brand springs don't come close to advertised spec's