FROM STI website
Q:
What is the recoil spring weight in my gun?
A:
My Local Copy of FAQ:
Frequently Asked Questions
1. What is the
difference between conventional and variable recoil springs?
2. Should I
use a conventional or variable spring when both are
available?
3. What weight
recoil spring should I use with a particular load?
4. How often
should I change my recoil spring?
5. How often
should I change magazine spring? Should I unload my magazines, rotate
magazines, load with fewer rounds?
6. My spring
got shorter after I used it for a short time. Is it bad?
7. My lighter
spring is longer than the heavier spring for the same gun. Is this a
problem?
8. The spring
I purchased is longer than the original spring so I don't think it will
fit.
9. What is
the difference between a firing pin spring and a striker spring?
10. I can't
find the spring I need, can Wolff make me a custom spring?
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 two 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.
9. What is the difference between a firing pin spring and
a striker spring?
A firing pin spring is actually a return spring as it
returns and keeps the firing pin
retracted. The firing pin spring works in front of
the firing pin pushing the firing pin away from the primer usually
keeping it retracted in the slide. When the firing
pin is struck by the hammer the impact force of the hammer
overcomes the retraction force of firing pin spring and drives
the firing pin into the primer.
A striker
spring is actually the spring that causes the firing pin to striker the
primer. The striker spring works behind the firing
pin. When the gun is in the cocked position, the striker
spring is compressed behind the firing pin. When the trigger is pulled
the firing pin is released and the striker spring pushes the firing pin
into the primer. While technically incorrect, a striker
spring is often referred to as a firing pin spring.
10. I can't find the spring I need, can Wolff make me a
custom spring?
Unfortunately,
we do not make custom springs on a individual basis due to the set-up
time and costs involved. If however you should need production
quantities of springs, we will be please to quote.