Recoil, and other springs, in the 1911 should be replaced periodically. And while a spring may be rated at a certain compression rate that does not mean that it is at its rated spring rate. Or, you may have a few springs lying around and need to know what their spring rate is. For my use, I simply wanted to know what rate recoil spring came with a new 1911 pistol. I needed a way to measure them and then transfer that knowledge to readers of my firearm reviews. I also needed to know what recoil springs were in other semi-automatic pistols. What I need was a means to measure spring rate. I found several videos on making a recoil spring tester from scratch. And while that information is useful, and I could have made a spring rate tester from scratch given I had a metal shop available to me, this new product (to me) gave me two things; a means to measure recoil and other firearm springs, and something else to write about. What I do for my readers!
First, let us look at the manufacturer’s claim about the product.
“This tool helps sort recoil springs as well as other types of firearm springs by pull weight so you can use the correct spring for your load. This tester comes with a digital scale. Use is simple, just insert spring on bolt, insert in tool, attach coupler and scale. Pull until proper compression is achieved. Tool is marked with a line at 1.625″ which is the Mil-Spec compression length of a 1911 recoil spring. Beginning February 1, 2013, the Spring Tester will include the NEW adapter, Model #11539 to check mainsprings, firing pin springs etc.” – Source: Secure Firearm Products
The Spring Tester w/Digital Scale Kit, Model Number 11490-SR-D arrived with the following components in a large zip-lock plastic bag with some components packed in a separate zip-lock bag or in a box (scale unit):
- Large bolt for recoil spring.
- Coupler that fits the large and small bolt.
- Small bolt for testing smaller springs (mainsprings, firing pin springs etc.).
- Small bolt nut and centering washers.
- Digital Scale (battery not included). 2-each AAA batteries are required.
The Scale (Gauge)
The scale, a digital unit, is an accurate weighing unit with a hold (stable) feature and an LCD display. It offers a unit selection (pounds and kilograms), automatic power off, and zeroing capabilities.
Instruction are provided in two languages; Chinese and translated Chinese to English.
Put the scale in a vertical position without weight and press the POWER button. Two seconds later, the display will indicate 0.00 (pounds), 0 (grams), 0.0 (ounces), or 0.000 (kilograms) and the selected unit (see Unit Selection). The scale will be ready for weight.
The Tare button allows the zeroing of the scale.
When the weight data is stable, this stable data will be locked, and a “Hold” sign is indicated on the display. (Author’s Note: This “stable data” is extremely hard to achieve.)
The unit key provides a means to select between different units; pounds (lb), grams (g), kilograms (kg), or ounces (oz), as indicated on the display.
The LED exhibits several indications:
- Solid red during power up and then extinguishes.
- Flashes during measurement pull.
- Solid red when final measurement is achieved (see also, Hold Function).
Automatic Shut Off
The unit automatically shuts off after 60 seconds of non-use.
The front panel is an LCD (Liquid Crystal Display) type that is capable of display 4 number and a decimal. The backlighting appears for 2 seconds after power on and then goes off. The display shuts off after power is removed from the unit (automatically or after manually power off).
The hook is suspended by a short length of chain. The hook can be stored in the rear of the unit. During use, the hook is looped through the adapter that is attached to the rod.
Using the Spring Tester
The cylinder is market at with a line at 1.625″ which is the Mil-Spec compression length of a 1911 recoil spring.
To use the spring rate tester for measuring recoil spring rates, perform the following.
- Slide the recoil spring onto the large bolt.
- Insert the bolt and spring assembly into the cylinder.
- Attach the coupler to the bolt. Screw the coupler onto the bolt. There will be free play of the spring/bolt assembly. The free length prior to compression is not important.
- Attach the digital gauge to the coupler.
- Push the POWER button to apply power to the digital gauge. The red LED will illuminate, and the display will be active.
- Hold the cylinder in one hand and pull the gauge by the strap until the head of the bolt reaches the 1.625″ mark, note the display on the digital gauge. The value indicated on the display is the rate of the spring in in the selected unit (pounds, grams, kilograms, or ounces).
- When completed measuring, press the EXIT button. The digital gauge turns off.
The Good, the Bad, and the Ugly
The stability while trying to measure a spring rate with this device is well, questionable at best. When you are trying to hold the tube while pulling on the strap of the scale, and trying to read the display, is not the most stable platform. I decided that something, the tube, the scale, or both had to be stabilized. I have several metal shelves and the loop of the scale was looped around the top of one of the end posts. That served well enough to stabilize the scale. All I had to do was pull the rod (no jokes, please!).
The first spring that I decided to test was a new, Wilson Combat #16 spring for a full-size 1911. Unfortunately, the spring was too long to fit fully into the tube and placed the head of the bolt (approximately) 0.5 inch above the tube. That put me off for a bit. I did realize that new recoil spring would be longer than one that is used, as springs will shorten by usage and constant compression. Pushing the bolt head into the tube would add some compression, but not much to speak of when pounds are being considered. I secured the strap of the scale, pulled the tube, and 16.4 pounds was indicated on the scale at the 1.625 mark. Lo and behold!
The second spring to be measured was a new, Wilson Combat #20 recoil spring for a “Commander-Length” 1911. The spring and rod assembly fit well within the tube. I had made a mark on the tube at 1 7/16-inch, since the spring length was 6-inches and that mark would be (approximately) 24.8% of the total length of the spring (see On Measuring Recoil Spring Rates for more information). Sure enough! The spring rate measured at 19.875 pounds. Kuhl!
The final spring to be tested was one that is currently installed in my Rock Island Armory FA Tactical 1911, which has had (approximately) 500 rounds run through it since a recoil spring change. I had replaced the original spring with a Wolf spring, but I could not remember what I replaced it with, a #16 or a #18. Hopefully, the tester would let me know. The spring length of the spring was 5.5 inches after being compressed for a while. At the measurement mark, the spring’s rate was (approximately) 15.75 pounds and that indicates that I may want to consider changing this spring out for a fresh one, although the recommended change is 2,000 rounds (see Replacing Springs for more information).
Now, note that these are not precise measurements like you would find in a laboratory. The measurements are simply close approximates; however, they are close enough to provide a relative indication of a recoil springs condition regarding its spring rate.
Thus far, there is mostly good, one bad, and no ugly.
On Measuring Recoil Spring Rates
While the Spring Tester with Digital Scale kit is not what I would consider a tool of a professional, it does the job it is intended to do – measure recoil and other spring rates, once you purchase a battery for the gauge, as a battery is not included. Some assembly required to use.
By using it I have learned what the relative spring rates are in my 1911 pistols, and several others whose recoil springs are not captive. Other non-captive recoil springs can also be measured. Although the line at 1.625″ is for 1911 ‘Government’ pistols, it can also be used with springs other than those found in a 1911. The distance also depends on if the recoil spring is a progressive spring or not. We need to look at springs in general.
The spring is (for the most part) wound steel and is defined by its rate. Rate is a measurement of the force required to compress the spring and is expressed in pounds per inch. For instance, a spring with a 100 lbs./inch rate will require 100 lbs. to compress it one inch. Each subsequent inch of compression would require an additional 100 lbs. of force. This is referred to as a straight or linear rate spring. The alternative is a progressive rate spring which allows a single spring to exhibit multiple rates. By utilizing varied spacing spring coils, the initial rate may be 60 lbs./inch, requiring 60 lbs. of force to compress it one inch. Then each subsequent inch of movement would require progressively more than 60 lbs. of force such as 75 lbs. more for the second inch, 100 lbs. more for the third inch etc. Progressive-rate springs become stiffer quicker as they are compressed.
With that said, calculating spring rates is a complicated affair that the Spring Tester w/Digital Scale Kit is supposed to make simple. If you are a geek that wants to know how spring rates are actually measured, click here.
What rate is the recoil spring in your 1911 supposed to be? In most cases, this might mean contacting the firearm’s manufacture to find the answer. However, there are some guidelines for the 1911. Here are some recoil spring and mainspring rates posted by Rock Island Armory for their pistols and can also serve as a guide to spring rates of other 1911 pistols, but you should verify the rate of springs in your specific 1911 with the manufacturer.
Recoil Spring Weights:
|Full Size||18 lbs||16 lbs||12 lbs||7 lbs||7-8 lbs||20 lbs|
|Mid-Size||20 lbs||20 lbs||14 lbs||9 lbs||N/A||24 lbs|
|Compact Size||24 lbs||20 lbs||16 lbs||N/A||N/A||N/A|
Mainspring (Hammer Spring) Weights
|Full Size||18 lbs||18 lbs||18 lbs||17 lbs||17 lbs||25 lbs|
|Mid-Size||20 lbs||20 lbs||18 lbs||N/A||N/A||25 lbs|
|Compact Size||24 lbs||22 lbs||18 lbs||N/A||N/A||N/A|
As you can see, the shorter the barrel on the 1911, the greater the spring rate for the recoil and mainspring. Of course, the rates shown are for manufactured pistols. If you are running hot ammunition, you may have increased your recoil spring rate to handle the increase in power.
The spring rate of my Ruger 1911 CMD-A Lightweight Commander should be around 20 pounds. The pistol has been shot, with (approximately) 500 rounds going down the pipe after a spring change, and it is possible that the spring has shortened, and the spring rate has decreased with use, but it will serve well enough as a test spring. I also have some new and still in the package Wolf springs for the 1911 that are rated at 18 pounds and 20 pounds by Wilson Combat. They will also serve as test springs.
There are still several unknowns. Although I do know where the 1.625″ mark on the cylinder of the spring rate tester was derived from, I do not know what the original specification was derived from. “While 1911 Auto recoil springs are available in a variety of weights, 16 pounds is considered the standard for full-size guns with 5″ barrels. Just how is this figure of 16 pounds determined? In full recoil, the space available for the recoil spring to occupy is 1.625″. At this point in its compression, its stored energy is 16 pounds. A 15 pound spring would store 15 pounds of energy when compressed to 1.625″, etc.”
Since a Commander 1911 recoil spring is shorter than a Government recoil spring, do I use the same 1.625″ mark, or would it be shorter? What is the standard length of a Government 1911 pistol’s, recoil spring? One source cited that a Government model 1911 recoil spring length is 6.55 inches long with 30 coils when new at a spring rate of 18 pounds per square inch.
So, let us consider the above for a bit. 1.625 inches is 24.8% of the recoil spring’s length of 6.55 inches. Does that percentage apply to shorter recoil springs? Read what follows.
Another source states that similar pistols but with shorter slides, such as Commander or Officer’s ACP-length models, require springs that are not only shorter, but have different compression weights. A standard Commander spring is 18 pounds when compressed to 1.125″ (1 1/8”), while the Officers ACP spring system must store 22 pounds of energy when compressed to .700″. The free length prior to compression is not important, if it fits within the available space.
Wilson Combat recommends changing the recoil, firing pin spring, and mainspring at the following intervals:
- Recoil spring every 2,000 rounds
- Firing pin spring every 5,000 rounds
- Hammer spring every 25,000 rounds
Another measurement that I had read regarding recoil springs is to replace the spring if it is ¾ of its length as compared to when the spring was new.
Now, I do not know about you, but I am a bit lax at measuring the length of the recoil springs in my 1911 pistols (or any semi-automatic pistol with a non-captive recoil spring) when I first get them, but maybe I should from now on.
Another source cites: “… changes in the weight of the slide and barrel combination, addition of barrel weights or compensators, optical sights attached directly to the slide, or changes to the ballistics of your ammunition may require a change in spring weight. The rule of thumb is to use the heaviest spring available while maintaining reliable function. A fair indicator is how far from the shooter the ejected cases land. Less than three feet may indicate the need for a lighter spring, while more than six feet may indicate the need for a heavier spring. Keep in mind that too light a spring may result in damage to your pistol.”
Also, take into consideration the angle of departure of expended cases, which may indicate either recoil spring tension or extractor issues or both. Some source claim that the proper trajectory of spent cases should be to the side and slightly rearward. I have tuned a few extractors and there is some validity to that. Again, we rarely, if ever, test the extractor tension when purchasing a new 1911 pistol and we rely on the manufacturer to get things right in that department. But, extractor tensions are not the subject of this article. However, you can find information about an extractor tuning system at: Weigand Extractor Adjusting Tools – Product Review.
While I did not want to take you on a journey regarding recoil springs, rates, lengths, etc. I do believe that I did, however. With that said, I hope that the information was useful.
The SPRING TESTER W/DIGITAL SCALE KIT from Secure Firearm Products does what it is intended to do, measure 1911 recoil and smaller 1911 springs.
As I mentioned previously, the SPRING TESTER W/DIGITAL SCALE KIT from Secure Firearm Products will provide relative and not precise measurement of you 1911 recoil spring’s rate. However, it is close enough to determine what shape the recoil spring is in, and that should give you some peace of mind.
As for the recoil spring in my Rock Island Armory 1911 FS Tactical, I have a few #16 springs on order.
Spring Tester w/Digital Scale Kit, Model Number 11490-SR-D: https://www.securefirearmproducts.com/Model_Details.php?modelno=11490-SR-D