COMPS competition spring

Description

Magazine spring family engineered for competition shotguns. Available in factory, medium and light version.

Less loading resistance means increased loading speed and success rate. And correct magazine spring rating is important for the functionality of your shotgun.

In other commercial shotgun magazine springs there can be even a 30% or more variance in force output between brands and even production batches/years as manufacturers change the specifications. COMPS gives you fixed standards, they are high quality shotgun magazine springs, made to exact specifications, every production batch tested and measured for output spring force. COMPS is also available with different ratings and data is collected and published to help you tune your competition shotgun.

Specifications:

• Length for light 1200mm, medium 1200mm and factory 1250mm
• Light for most modern semi-auto competition shotguns with up to 12 shell tube
• Medium for most pump-action shotguns with up to 12 shell tube, or increased feed reliability for semi-automatics
• Factory rating for pump action shotguns without feed modifications, very long tubes and increased reliability for all platforms when dirty or other problems with feeding
• High quality steel spring wire with color marker (spring steel not colored, as in the picture)

Instructions:

• Remove any color/power markers or packaging material from the spring
• Assemble spring to the magazine tube and fully compress it 4-5 times (fill the magazine full of shells)
• Spring will take some set and shorten approx 40-90mm
• Cut the spring to preferred length, after the spring has taken a set
  • • You can always leave the spring longer than recommended minimum, this will add reliability
    • For auto-loading lifter users, see FAQ
    • Recommended minimum for Light in 12 shell tube: tube length + 350mm (no need to cut)
    • Recommended minimum for Light in 10 shell tube: tube length + 300mm
    • Recommended minimum for Medium in 12 shell tube: tube length + 250mm
    • Recommended minimum for Medium in 10 shell tube: tube length + 200mm
    • Recommended minimum for Factory in 14 shell tube: tube length + 250mm
    • Recommended minimum for Factory in 12 shell tube: tube length + 200mm
• Make sure your magazine tube and follower is clean and smooth
• Always test the functionality of your setup in training
• Ready to rock&roll

 

Comparison chart

 

 

Advanced instructions:

Cutting the spring shorter than recommended will increase the magazine capacity by approx 1mm per cut coil. If this is not absolutely needed, do not do it. Total spring force and work required to fill the magazine tube will anyway remain very similar, as springs will become stiffer when coils are cut. Cutting the spring will only reduce the spring force on the first shells so magazine capacity is the only reason to go below minimum recommendation. Depending on the shotgun, additional 4-8mm of magazine capacity could be achieved by cutting the spring below recommendation, while the shotgun still remains operational.

Timing of the shotgun shell feed is a combination of gun, ammunition and also the shooter physique (recoil control). Always test your setup in training!

Q&A can be found below

 

 

Collected data

Last updated 26.9.2021

 

Model	Feed timing modifications	Mag tube	Spring	Comments
Benelli M2	–	12 and 10	COMPS-LIGHT + 350 and 300mm	OK for some users, but some shotgun/shooter combinations have problems
Benelli M2	–	12 and 10	COMPS-MEDIUM  + 250 and 200	OK
Beretta 1301	–	12 and 10	COMPS-LIGHT + 350 and 300mm	OK
Beretta 1301		10	COMPS-LIGHT + 100mm	Does not always feed the last shell
Benelli SuperNova	King Competition RSB2	10+T	COMPS-MEDIUM + 200mm	OK (telescope inner tube is 10 shells)
Benelli Supernova	King Competition RSB2	10	COMPS-LIGHT	Occasional feed speed problems with full tube and loose/relaxed shooting stance
Benelli Supernova	Innovatac RSB3 (reduced overlap)	10+T	COMPS-LIGHT + 300mm	Works with 28g birdshot, but is on limit. MEDIUM spring is recommended.
Benelli Supernova	Innovatac RSB3 (reduced overlap)	12	COMPS-MEDIUM + 220mm	OK
Remington Versamax	–	12	COMPS-LIGHT + 350	OK
Remington 870	DIY welded (reduced overlap)	10+T	COMPS-LIGHT+ 300mm	Works with 28g birdshot, but is on limit. MEDIUM spring is recommended.
Winchester 1300	–	10+T	COMPS-LIGHT + 350	Occasional feed speed problems
Winchester 1300	–	10+T	COMPS-MEDIUM + 30mm	OK with 28g loads, feed problems with 34g loads
Winchester 1300	DIY modified (reduced overlap)	10+T	COMPS-MEDIUM + 200mm	OK up to 34g loads
Browning A5	–	12	COMPS-LIGHT + 250	Test gun works with all competition ammo even with spring shorter than recommendation
Mossberg JM PRO	–	12	COMPS-LIGHT + 200	Test gun runs OK even with spring shorter than recommendation
Benelli Nova Speed	–	12	COMPS-LIGHT + 250	Test gun runs OK even with spring shorter than recommended. This shotgun is different from other pump action shotguns and will work with a light spring.
Winchester X3		11	COMPS-MEDIUM + 250	OK

*T = telescoping magazine tube

 

Q: “how to fit the spring for auto-loading lifter shotgun”
A: ” auto-loading lifter will require additional magazine spring force to operate the bolt release. Add +200mm extra for light spring and +150mm for medium spring. Shotgun with very smooth parts can operate with shorter magazine spring than this, but it must be tested. Start with extra length”

Q: “will the spring work in shorter magazine tube?”
A: “yes, and you can cut extra -50mm off the spring if using a 8 shell tube vs. 10. Shorter tube is always easier to tune to be reliable”

Q: “should I put the closed or cut end inside the follower?”
A: “The spring will compress more nicely inside the tube if you put the cut end inside the follower, but it will work either way”

Q: “how much I can cut the spring?”
A: “depends how much resistance you shotgun feed system (shell latch, tube, follower) has for the last shells. Stay with the recommendations if possible.”

Q: “what is my current spring rating from other manufacturer”
A: “Can be anything, likely it is 70-100% in the spring scale, there is a big variance between spring manufacturers and production batches”

Q: “I am running 32g loads or heavier”
A: “spring designs are sufficient for the additional mass of 32g, however they are optimized for typical 28g competition loads. Always test your setup before a match. Increase the spring rating if you are shooting very heavy loads.”

Q: “why does longer magazine tube require a spring with stronger rating”
A: “because additional shells and the additional inertial mass will slow down the feeding”

Q: “I have a sticky magazine tube”
A: “check that it is clean, follower is suitable and the inner connection between the tube and tube extension is smooth”

Q: “do I need to upgrade the feed timing on pump-action shotgun?”
A: “no, If you do not pump too fast”

Q: “why does pump action require stronger spring?”
A: “because of the two shell latch design that will cut of the feeding at the during the action travel. Unlike modern semi-auto shell one latch design that will remain open the whole action cycle”

Q: “does longer spring mean stronger spring with shotgun mag tube springs?”
A: “no, length of the spring mostly relates to pre-load that is needed to feed the last shells. Actual spring strength is a combination of wire, diameter, pitch, material etc.”

Q: “what spring to use with telescopic magazine tube?”
A: “the inner tube spring is recommended to be lighter when compressed than the telescoping spring, for the telescope to work in the right sequence. Light or medium is typically ok. Strong factory spring can create problems in a telescopic tube.”

Q: “can I make the spring lighter just by cutting it”
A: “no, you can only reduce the pre-load by cutting a spring shorter. This means that the first few shells will be lighter to load and will feed with less reliability. With a cut spring you will still get almost the same resistance when more than 2 shells are inserted.

Q: “is it possible to leave the color marker on the spring”
A: “no problems reported of leaving it in, it will take up a few millimeters of capacity though”

Q: “I experience feed problems with recommended spring rating”
A: “a lot of data of numerous users has been collected to find working combinations in different shotgun types and it is also updated when new information is available. Reasonable safety margin has been designed in to the spring ratings, so there is room for the shotgun to get dirty or have a little sticky feeding. However if the feeding in the shotgun is very sticky, a reduced power spring can bring out problems. Recommended solution for this is smooth out the feeding inside the shotgun. If this is not possible, the other option is of course change in to a stronger spring that will push shells through any scratches, notches or other edges that can catch and stop the shell. However if the shells catch inside the shotgun, there is no guarantee that even a strong spring will feed reliably.”

Q: “I have a sticky receiver”
A: “It is not uncommon for the shotgun to have edges inside the receiver that can catch the rim of the shell and stop the feeding. These edges can also form over time when using the shotgun. Check for any edges that can catch the shell rim and smooth them out. Edges can be found in the shell latch, lifter, receiver body etc.”