Underworld Arms
140mm Mag Spring 120% 11 Coil
140mm Mag Spring 120% 11 Coil
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2011 17rd and 20rd round magazines use the same length spring. Owners often find that this results in less than optimal spring power in their 20rd magazines, which can result in feed inconsistencies and failure to lock back on empty. Our 11 coil 120% spring for 20rd magazines solves this issue and also allows you to add a +3 extension to your 140mm 20rd 9mm magazine tubes and your 140mm 13rd .45acp magazine tubes.
These springs are manufactured by AQS the factory that makes springs for Noveske, Apex, Sig, CMMG, POF-USA. We lucked out and our shop just happened to be ten minutes from their factory.
Specifications
Compatible with Staccato/Mac/Tisas/Kimber/Prodigy 140mm tubes
Material: 17-7 Stainless Steel
My Prodigy came with (1) 17 rd mag and (1) 20 rd mag. Apparently, they both used the same spring, at least in early model production. After acquiring additional mags, I noticed a difference in springs especially in the 20s. Springfield may have fixed that long ago and started sending out better springs in the 20s. I was having lock back issues with my factory mags, so put these extra power springs in a standard 20 and there you go! No issues even 1000 rds later. For my purposes, I also got the Underworld Arms +3 base pads, so these became a vital upgrade, and now live happily in all 6 of my mags! Great option, great service and availability, shipping was fast and will buy again to have some spares.
They were perfect for upgrading my magazines
Amazing springs work well with my Atlas tooless guide rod also the Cerberus frame mounted compensator shoots extremely flat when adjusted to the spring weights
I replaced the stock springs on Tisas Night Stalker 17-round and Atlas 20-round mags with the 140mm 120% springs, and they have worked perfectly.
Prompt shipping. Springs are great in my magazines for my Kimber 2k11. Ordered the MK2 mag extensions today
