Springfield 1911 9mm Loaded Target to 40 S&W begins.

[Quack]

those that has an SA Loaded 9mm 1911, have you noticed the main spring cap (which connects with the strut), appears to be larger than normal? I compared it with my 2011 pistols and it is longer....I could not fit an ISMI mainspring a a result.

Yes, because SA has the ILS in the MSH.

[RPatton]

I can't recall ever seeing a factory open ended mainspring.

[jimbullet]

So it appears that I need to trim the ISMI main spring to get it to fit into the SA. that should be okay right?

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[BeerBaron]

Cutting the spring effects its weight.

Better bet is buy a new msh and spring cap.

Just be aware if you fit say a 17 or 19lb main spring you may get light strikes.

Springfield set the gun up with a very heavy hammer spring and use a titanium firing pin a very strong firing pin spring.

So with a more conventional power mainspring you may not get good primer strikes. It's a system so if changing one part you need to change the firing pin spring and ideally fit a steel firing pin.

The reason they set them up that way is since they don't have a drop safety using a strong fp spring and lightweight firing pin makes a drop fire very unlikely.

One benefit is heavy hammer spring keeps the slide in battery longer during firing. Another claimed benefit is with the light firing pin is shorter lock time. Ie time from when trigger is pulled to when firing pin hits primer. With heavy hammer spring and titanium fp (low inertia) it should be faster but we're talking probably milliseconds.

You just need to bear this in mind when tuning 'the system'. Most people swap them out with 'known' parts.

Steel firing pin

Wolf or ismi firing pin spring

Change out msh

Spring cap

Hammer spring 17 or 19lb

But you can make it work with stock parts too.

Edited January 25, 2016 by BeerBaron

[robertg5322]

When I got mine, I put a new MSH/Magwell in it, with stock cap and 17lb IMSI (I think) mainspring. Has worked fine for about 4k rounds so far.

I figured if I had light strike issues, I'd change the firing pin and/or firing pin spring, but the need hasn't popped up yet...

Firing pin is one of the few small parts that I didn't replace (Ejector, extractor and barrel link being the others) in my quest to make the gun better. Still loose as hell but shoots real nice.

[Aircooled6racer]

Hello: Cutting the spring will not effect it's spring weight at all. If you use a 17lb ISMI mainspring you will have to use a extra power firing pin spring. Thanks, Eric

[zzt]

You can convert the existing SA MSH to standard just by swapping out the parts. Several people at the club have done just that. One runs a Loaded with an 18lb mainspring and the original firing pin and spring and has no ignition issues with factory ammo or reloads using WLPs.

[StraightSh00ter]

So it appears that I need to trim the ISMI main spring to get it to fit into the SA. that should be okay right?

Sent from my iPhone using Tapatalk

The spring length is not a problem. I just changed out the hammer spring in one of my guns with a Wolff 17lb spring, and the spring was much longer like in the pic above. While the spring is longer, the wire is also a bit thinner and there are more coils. This lets the spring compress more, and for the same 17lbs spring allows for less stress in the spring steel. This creates a spring that lasts longer.

It is a popular misconception that cutting coils off a spring reduces the power. The only thing it changes is the preload and the available amount of travel.

[RPatton]

Cutting coils may not affect the weight but it will affect the force with which the hammer hits the firing pin. Cut off enough and it won't fire.