[Chico]

In general, the more powerful the load the greater the need for a more powerful spring. Bullseye shooters with light loads will use the springs down toward the 10 lb range. I load my full-sized 1911 for IDPA and IPSC, both requiring power factors of greater than 165,000 (velocity times bullet weight) and use a 16 lb spring. The 16 lb spring is considered "stock". If you are shooting hotter or more powerful loads, then 18 or 20 lb springs will likely be needed.
There are two things to consider, the first being the most important- battering of the parts. The next is the speed & "slam" of the slide returning to battery.

 

[eljay45]

My understanding is the gun should throw brass 6 to 8 feet. spring too weak, brass goes further,spring to strong or heavy the brass doesn't go as far. I changa my spring every 2000 rounds. I have heard to do it when the spring is about 1 inch shorter than a new one

 

[eljay45]

I never get to be the first one to post a reply ,guess I need tping lessons

 

[Joe D]

Most of the top guns in the IPSC game use light springs (11-12 lb.) with thick shock buffs. Makes the slide cycle very fast without frame damage. I tried it in both .40 and .45. The brass ejects forward. I have not shot the light springs enough to determine if I like the feel of the recoil cycle.

 

[LenB]

Isn't the mainspring also a factor? Yeah, the slide is recoiling against the recoil spring, but it's also going against the mainspring.

 

[shane45-1911]

As mentioned, stock weight is 16 lbs. in a 5" model, 18 lbs. in Commander length. When to change them depends on how hot your loads are. A general rule of thumb is every 2000 - 3000 rds.

You will know if you have too light a spring by brass ejecting too far, and by possible smear (tear-shape) firing pin marks on your primers. You may also be experiencing some FTF with the bullet nose jammed into the feed ramp, or vertical into the top of the barrel hood/chamber.

Too heavy will cause FTE more frequently.

LenB mentions that the mainspring (hammer spring) factor is also involved, and it is to some degree. If you have a lighter mainspring than stock, you may need to go to a lighter recoil spring. The hammer tension against the slide does play a small factor.

[This message has been edited by shane45-1911 (edited 09-05-2001).]