My Account (Sign in)
Your basket is empty.
0
Basket
contact us by phone Help and contact
Free standard delivery over £199
100-day return policy
My Account (Sign in)
Wish list
Your basket is empty. (0)
Basket
Newsletter Newsletter
Sale

Over 300,000 customers - we say thank you!

4.93/5 "Very good" (1400+ reviews)

40,000+ products for hunting and shooting sports

Handgun Parts Frame Parts Mainspring Parts Mainsprings ISMI 17 LB. C/S SPRING Support

The ISMI 17 lb. mainspring offers superior durability and consistent trigger pull, engineered from chrome silicon or stainless steel for reliable performance.

ISMI 17 LB. C/S SPRING

445105017
Variations
Filters:
Variations:

Variations:

The ISMI 17 lb. mainspring offers superior durability and consistent trigger pull, engineered from chrome silicon or stainless steel for reliable performance.
1911 MAINSPRING - 17 LB. C/S SPRING
19.9 GBP 0 £19.90 *
Backorderable
Make: 1911 Model: Government, Commander Product no.: 445105017
Backorderable
19.9 GBP 0 £19.90 *
-10 %
The ISMI 1911 Mainspring offers maximum durability and reliability, designed to aerospace specs for consistent trigger pull and reliable ignition.
1911 MAINSPRING - 15 LB. C/S SPRING
17.9 GBP 14 £17.90 * £19.90
In stock
Make: 1911 Model: Government, Commander Product no.: 445004014
In stock
17.9 GBP 14 £17.90 * £19.90
-10 %
Experience unmatched reliability and consistency with ISMI's 22 lb. 1911 mainspring, crafted from durable chrome silicon or stainless steel for optimal performance.
1911 MAINSPRING - 22 LB. 1911 S/S SPRING, EACH
17.9 GBP 5 £17.90 * £19.90
In stock
Make: 1911 Model: Government, Commander Product no.: 445000023
In stock
17.9 GBP 5 £17.90 * £19.90
Achieve maximum reliability and consistency with the ISMI 19 lb. stainless steel mainspring, engineered to aerospace specs for durability and performance.
1911 MAINSPRING - 19 LB. S/S SPRING, EACH
19.9 GBP 0 £19.90 *
Backorderable
Make: 1911 Model: Government, Commander Product no.: 445105191
Backorderable
19.9 GBP 0 £19.90 *
Experience unmatched reliability and durability with ISMI's 1911 Mainspring, designed for consistent trigger pull and ignition, crafted to aerospace specs.
1911 MAINSPRING - 19 LB. S/S SPRING, 5-PAK
Not available
Make: 1911 Model: Government, Commander Product no.: 445105195
Not available
34.9 GBP 0 £34.90 *
17.9 19.9 5 GBP
19.9 GBP £19.90

Prices inclusive of duty & VAT.

Product no.: 445105017

Mfr. No.: 17MS

CAD designed and built to Aerospace specifications from chrome silicon, corrosion resistant, stainless steel or chrome vanadium for maximum durability, consistency and reliable performance. Built to aerospace specifications; heat treated, shot peened and fully stress relieved to minimize spring set. 1911 AUTO MAINSPRING - Stainless steel (SS) or chrome silicon (CS); wound in the very popular 19 lb. and 17 lb. rate for lighter, consistent trigger pull with reliable ignition.
Backorderable
3/5 - 2 Customers
1
2
3
4
5
6
7
8
9
10+
£19.90

Prices inclusive of duty & VAT.

1
2
3
4
5
6
7
8
9
10+

Backorderable, delivery time approx. 4-12 weeks from the USA warehouse.

100-Day Return Policy

Backorderable, delivery time approx. 4-12 weeks from the USA warehouse.

100-Day Return Policy
No charges until we ship
No charge:
Your credit card will not be charged when you place your order.

No commitments:
You are under no obligation until the goods are shipped. You can cancel your order at any time before shipping - free of charge.

Not until shipping:
Your credit card will only be charged once we ship your order. Not before.
  • Maximum durability and reliability
  • Consistent trigger pull
  • Corrosion resistant materials
Wish List Ask question
17.9 19.9 5 GBP
Description Specification Customers reviews Accessories

ISMI 17 LB. C/S SPRING

19.9 GBP £19.90

Prices inclusive of duty & VAT.

1
2
3
4
5
6
7
8
9
10+
£19.90

Prices inclusive of duty & VAT.

1
2
3
4
5
6
7
8
9
10+

Backorderable, delivery time approx. 4-12 weeks from the USA warehouse.

100-Day Return Policy

Description:

Enhance your 1911 with ISMI's premium mainspring!

The 1911 MAINSPRING, ISMI 17 LB. C/S SPRING is engineered for maximum consistency and reliability, making it an essential upgrade for your firearm.

Product Features

  • Material: Available in chrome silicon or stainless steel
  • Durability: Designed to aerospace specifications for exceptional performance
  • Heat Treatment: Heat treated, shot peened, and fully stress relieved to minimize spring set
  • Trigger Pull: Wound in popular 19 lb. and 17 lb. rates for a lighter, consistent trigger pull with reliable ignition

Specifications

  • Chrome silicon or stainless steel round wire
  • Chrome vanadium flat wire

Upgrade your 1911 with the ISMI mainspring and experience improved performance and reliability on the range!



Attributes

  • Model: 
    Commander
    , 
    Government
  • Weapon type: 
    1911
  • Delivery weight: 0.005kg
  • Shipping height: 1mm
  • Shipping width: 83mm
  • Shipping length: 146mm

Item details

Made in USA

Customers reviews

Customer ratings (2)

3 / 5
Not recommended

Brownells USA Too weak... 09/03/2015

this ISMI 15 lb mainspring is so weak cannot ignite the primers…15lb of Wolff is way better and would ignite any primers….I have 3 and its still sitting gathering dust….

Definitely recommended

Brownells USA GOOD BUY! 28/01/2014

I used this in conjuction with an 18.5 lb recoil spring in a High Standard 1911, Also used a Wilson Combat hammer and sear. This mainspring will lighten your trigger pull, seems to be of good quality.

Variations:

The ISMI 17 lb. mainspring offers superior durability and consistent trigger pull, engineered from chrome silicon or stainless steel for reliable performance.
1911 MAINSPRING - 17 LB. C/S SPRING
19.9 GBP 0 £19.90 *
Backorderable
Make: 1911 Model: Government, Commander Product no.: 445105017
Backorderable
19.9 GBP 0 £19.90 *
-10 %
The ISMI 1911 Mainspring offers maximum durability and reliability, designed to aerospace specs for consistent trigger pull and reliable ignition.
1911 MAINSPRING - 15 LB. C/S SPRING
17.9 GBP 14 £17.90 * £19.90
In stock
Make: 1911 Model: Government, Commander Product no.: 445004014
In stock
17.9 GBP 14 £17.90 * £19.90
-10 %
Experience unmatched reliability and consistency with ISMI's 22 lb. 1911 mainspring, crafted from durable chrome silicon or stainless steel for optimal performance.
1911 MAINSPRING - 22 LB. 1911 S/S SPRING, EACH
17.9 GBP 5 £17.90 * £19.90
In stock
Make: 1911 Model: Government, Commander Product no.: 445000023
In stock
17.9 GBP 5 £17.90 * £19.90
Achieve maximum reliability and consistency with the ISMI 19 lb. stainless steel mainspring, engineered to aerospace specs for durability and performance.
1911 MAINSPRING - 19 LB. S/S SPRING, EACH
19.9 GBP 0 £19.90 *
Backorderable
Make: 1911 Model: Government, Commander Product no.: 445105191
Backorderable
19.9 GBP 0 £19.90 *
Experience unmatched reliability and durability with ISMI's 1911 Mainspring, designed for consistent trigger pull and ignition, crafted to aerospace specs.
1911 MAINSPRING - 19 LB. S/S SPRING, 5-PAK
Not available
Make: 1911 Model: Government, Commander Product no.: 445105195
Not available
34.9 GBP 0 £34.90 *

Customers also bought

Alternative items

Oops! Something went wrong.

We encountered an error while loading this content. Please refresh the page to continue. If the issue persists, contact our customer support.

Site Navigation
Product Categories
Ordering
Customer Service

Welcome!

to Brownells UK, your destination for anything gun related. With our roots in a genuine passion for firearms, we bring you an unmatched selection of Gun Parts, Firearm Accessories, Gunsmithing Tools, Scopes & Red Dot Sights and Expert Knowledge.

Whether you're looking to maintain, repair, or upgrade, we've got what you need!

For Shooters, By Shooters
We share your enthusiasm and know exactly what you're looking for because we're part of the community.

Massive Selection
From the essentials to the unique, find everything under one roof.

Our blend of tradition and innovation
Shop with the convenience of modern technology, backed by a legacy of experience.

Browse our collection and discover why we're the trusted name in shooting sports & hunting.

Brownells Norge - Komplett utvalg av ladeutstyr, våpendeler, kuler, hylser, kikkerter, optikk og luftvåpen Brownells Österreich - Einer der größten Lieferanten für Waffenteile, Büchsenmacherzubehör & Schießsportzubehör Brownells Switzerland - Einer der größten Lieferanten für Waffenteile, Büchsenmacherzubehör & Schießsportzubehör Brownells Deutschland - Einer der größten Lieferanten für Waffenteile, Büchsenmacherzubehör & Schießsportzubehör Brownells France - Le plus grand fournisseur d'Accessoires pour le tir, Pièces détachées & Outils d'Armurier Brownells Iberica - El mayor proveedor de accesorios para el Tiro, Piezas y herramientas del armero. Brownells Sverige - Världens största leverantör av Vapendelar, Vapensmide Verktyg & Skyttetillbehör Brownells Suomi Brownells Italia - Il negozio del più grande rivenditore di componenti e accessori per armi da tiro, difesa e caccia Brownells Polska - Największy na świecie dostawca części broni, narzędzi rusznikarskich & akcesoriów strzeleckich Brownells Česko - Největší světový dodavatel součástí zbraní, střeleckého příslušenství a zbrojního nářadí
*
Prices inclusive of duty & VAT.

© 2025 Brownells UK
Part of the Brownells Europe Group

Logo Brownells
Classical viewClassical view Mobile viewMobile view
Back to top