Thanks. I went to the Wolff website and encountered many Java errors, so I switched to the no-frames version. I found the following FAQ and thought it might bear including here:
1. What is the difference between conventional and variable recoil springs?
The difference is both physical and operational. With a conventional spring, all the coils are spaced equally apart, except for the closed ends. In a variable recoil spring the space varies between coils with less space between coils at one end and more space between coils at the other end.
The way the 2 springs store energy is also different. For example if a conventional recoil spring is compressed 1/2", it might store 1 pound of energy. For every additional 1/2" this spring is compressed it would then store 1 additional pound of energy. When a variable recoil spring is compressed 1/2", it might store 1/4 pound of energy. The next half inch of compression might store 1/2 pound, the next half inch might store 3/4 pound and so on.
In other words, a conventional spring stores energy on a straight line and a variable spring stores energy on a curve. If both springs are rated at 16 pounds, they will both store 16 pounds when compressed to the same working length, but the way they get to 16 pounds is different.
2. Should I use a conventional or variable spring when both are available?
The choice is often very subjective. Conventional recoil springs are particularly beneficial when shooting heavier loads where keeping the slide closed as long as possible is desired. Variable recoil springs reduce the battery load values with increasingly greater recoil load values. This results in easier unlocking, improved recoil energy storage, dampening, feeding, breaching and lockup. Variable recoil springs are particularly beneficial with compensated pistols and when using light target loads where less recoil energy is available. The "correct type" of recoil spring is best determined through experimentation and your own personal preference.
3. What weight recoil spring should I use with a particular load?
This is a very common but hard question to answer in exact terms and in most cases an exact answer is not possible. There are many factors which influence the correct weight recoil spring to use. These factors include the particular ammunition brand and load, individual pistol characteristics, individual shooting styles and your individual, subjective feeling of how the gun shoots and should feel.
The factory spring weight is designed to operate the pistol with what would be considered average loads, plus or minus a little. It is not uncommon for manufacturers to specify what they consider a factory ammunition load.
In general terms, the heaviest recoil spring that will allow the pistol to function reliably is the best choice—tempered by the above factors. As a rule of thumb, if your spent casings are first hitting the ground in the 3 to 6 foot range, then the recoil spring is approximately correct. If you are ejecting beyond the 6-8 foot range, then a heavier recoil spring is generally required. If your casings are ejecting less than 3 feet, a lighter recoil spring may be needed to assure reliable functioning.
Taking these factors into consideration, it then comes down to how the gun feels and performs when shooting - in your judgment. However, using too light a recoil spring can result in damage to the pistol and possible injury to you.
4. How often should I change my springs?
The performance of your gun is the best indicator of when a spring needs to be replaced. Factors such as increased ejection distance, improper ejection and/or breeching, lighter hammer indents on primers, misfires, poor cartridge feeding from magazines, frequent jams, stove pipes and other malfunctions are all possible indications of fatigued springs or improper springs.
Springs such as magazine springs, striker springs and recoil springs are subjected to higher stress levels and will require more frequent replacement than other lower stressed springs such as firing pin springs and hammer springs.
Wolff springs are made with the highest grade materials and workmanship. Most Wolff [recoil] springs will remain stable for many thousands of rounds. Some recoil springs in compact pistols, especially where dual springs are used or are replaced by a single spring may require changing after 500 - 1500 rounds. Springs that become rusty, bent or otherwise damaged should always be replaced. Again, changes you observe in your firearm's performance are the best indicators that a change is needed.
5. How often should I change magazine spring? Should I unload my magazines, rotate magazines, load with fewer than the maximum rounds?
Magazine springs in semi-auto pistols are one of the most critical springs and are the subject of much debate and concern. Magazines which are kept fully loaded for long periods of time, such as in law enforcement and personal/home defense applications, will generally be subject to more fatigue than the weekend shooter's magazine springs in which the magazines are loaded up only when shooting.
Magazine design and capacity also affect the longevity of the spring. In many older pistol designs, maximum capacity was not the always the goal such as with the 7 round 1911 Colt magazines will last for years fully loaded. There was room for more spring material in these guns which reduces overall stress and increases the usable life of the spring.
More recently higher capacity magazine have become popular. These are designed to hold more rounds with less spring material often in the same space. This puts more stress on the spring and will cause it to fatigue at a faster rate. Unloading these magazines a round or two will help the life of the spring. Rotating fully loaded magazines will also help the problem somewhat but it is not always practical.
In applications where the magazine must be kept loaded at all times, a high quality magazine spring such as Wolff extra power magazine springs, will provide maximum life. Regular replacement of magazine springs will provide the best defense against failure from weak magazine springs. Regular shooting of the pistol is the best way to be sure the springs are still functioning reliably.
6. My spring got shorter after I used it for a short time. Is it bad?
Most new springs will take a set when they are first compressed. That means they will shorten up. This is a normal event and you should not be immediately alarmed. The greater the stress on the spring, generally the more set that will occur. All Wolff springs take this set into consideration. The ratings of the springs you receive are the ratings after the set has occurred. After set has taken place, the spring should remain essentially stable for the life of the spring.
7. My lighter [recoil] spring is longer than the heavier spring for the same gun. Is this a problem?
Wolff offers many springs in different weights for the same use. Factors such as the size of the wire, the number of coils, the outside diameter of the spring as well as the free length determine the strength of a particular spring. Often, lighter springs are longer than heavier springs because lighter wires and/or a different number of coils are used. Free length is then adjusted to achieve the exact strength desired.
8. The spring I purchased is longer than the original spring so I don't think it will fit.
The free length of a spring is not the most important factor in determining whether it will fit. Many Wolff springs are longer than factory springs. This is normal and the spring will fit.
The more important factor in determining whether a spring will fit is the number of coils in the spring times the diameter of the wire. For example, take 2 springs—one is 7 inches long and the other is 4 inches long. If both springs contain the same number of coils and use the same size wire, both springs will compress to the same solid lengths. The strengths will however be quite different but both springs will fit in the same application.
