1911 Recoil Spring, Ultra Compact

The SIG SAUER 1911 Ultra Compact Recoil Spring (Part Number 1911147-R) is a factory-original replacement part designed specifically for the 3.3-inch barrel "Ultra" 1911 models. This specific spring is critical for managing the high slide velocity of sub-compact .45 ACP pistols to ensure reliable cycling and prevent frame damage.

At a Glance:

• Compatibility: Designed for SIG SAUER 1911 Ultra Compact pistols.
• Caliber Support: primarily .45 ACP, but also compatible with Ultra models in 9mm, .38 Super, 10mm, and .40 S&W.
• Material: High-tensile steel with an unfinished/natural color.
• Design: This is a single, round-wire recoil spring designed to work with the Ultra Compact's specific guide rod and plug system. 

Proper maintenance of the recoil spring is more frequent in compact 1911s than in full-sized models due to the increased stress on the shorter spring.

• Replacement Interval: Users and experts on the SIG SAUER website suggest replacing this spring approximately every 1,000 to 1,500 rounds to maintain reliability and prevent feeding or ejection issues.
• Function: It regulates the slide's rearward travel and provides the necessary force to strip a new round from the magazine and return the slide to battery.
• Installation: While it is a direct drop-in part, Midwest Gun Works recommends that all factory parts be installed by a qualified gunsmith to ensure safe function. 

Regularly replacing this spring is the most effective way to prevent the "sluggish" slide feel or "failure to return to battery" common in high-mileage compact 1911s.