View Full Version : Lighter mainspring?

February 2, 2000, 06:27 PM
Check this out. Anything wrong with this scenerio.

I wanted a lighter trigger pull on my springfield 1911 "loaded". I did not feel confident enough to do it myself, nor did I want to spend $$ to get a smith to do it (only a few in my area, and from my and others experiences, I do not think they know what they are doing).

What I did was replace my factory mainspring with one from Brownells rated at 15#. I have yet to fire it. The trigger pull is lighter, but not as light as most other pistols I have handled with trigger jobs.

Could this cause any immediate or long term problems?

By the way, I onlt shoot casually at our local range.

Thanks for any responces.

Mike Baugh
February 2, 2000, 06:58 PM
I never go lower than 18# on a 1911 mainspring . You might be ok with the 15# but if I were going to carry the gun or use it for home defense I would go up to an 18# just in case you run across a hard primer . Good luck , Mike...

February 2, 2000, 07:00 PM
15# seems kind of lite for a mainspring, especially if you are shooting near normal loads. 19# is more what I would use. The mainspring works with the recoil spring to control slide lock/velocity, so any time you change the main spring, you need to up the recoil spring to compensate. This sometimes generates a little controversy, as most folks don't realize that the mainspring has anything to do with slide lock/velocity, but if you think about it carefully, you will see why. The slide has to compress the recoil spring as well as push the hammer back against the force of the main spring. When the spring rates are off, the slide will unlock too soon & move too fast, battering the gun un-necessarily & sometimes not pick up the next round in the magazine.
Try tuning the sear spring by bending the left leg back a little to lessen the pressure on the sear. Proceed carefully. A little goes a long way. Test by loading 1 round per mag & test fire. If the hammer doesn't follow the slide, load 2 rounds. Test fire again. Then load 3, etc.

George Stringer
February 2, 2000, 09:49 PM
Ehenz, 15# is a bit light. The lightest I install is 17# and I normally recommend a 19#. BBBBill made a good point about the springs relationship to the others in the gun. You should keep that in mind. George

February 5, 2000, 01:50 AM
While I agree a 15# spring MAY be a little light, also consider adding a titanium firing pin. You get a consistent fp strike every time and it should speed lock up time. Jim

James K
February 5, 2000, 10:25 PM
Good point, BBBill.

You are right that very few people consider that the hammer does help impede the slide. But fewer realize that the hammer does not remain in contact with the slide. The fast moving slide actually kicks the hammer back so that it continues on its own inertia until stopped by (in the 1911 type) the grip safety. The hammer then bounces off the grip safety and strikes the bottom of the firing pin tunnel, where it leaves a mark after a lot of shooting.

For an example of actually using the hammer in retarding a blowback action, check out the Astra 400 and 600, where the hammer is deliberately placed at a high mechanical disadvantage to help slow the slide.