Sig P226 40 to 9

[brucecrain]

I have a Sig P226 in 40/357 and was wanting to drop in a 9mm with a 15lbs spring. Will this work? I heard of people doing it but had some accuracy issues. I plan on buying a factory 9mm barrel and spring. Advise?

 

[BehindBlueI's]

Will it work? Yes, it will safely function.

Now, you didn't say what your intended use is for this post-conversion pistol, so you might find this matters and it might not.

1) Sights aren't going to be right. Sig uses different height sights for .40 and for 9mm guns. You will change your POI about 2" at 25y.
2) Lockup won't be as consistent. The external dimensions are slightly different, allowing more wiggle room. Your 2.5" at 25y gun is more likely to be a 5-6" gun at 25y. Or it might not be. Depends on tolerance stacking to some degree.

There are two better options. A dedicated conversion barrel or a Sig X-change slide. Both will have proper lockup, giving you better accuracy. The slide will also come with the correct 8/8 sights. The conversion barrel might still require a sight change, and could require gunsmith fitting (also depending on tolerance stacking).

So if you want factory siglight night sights, the x-change slide is a good option. If you're going to swap out sights anyway, a conversion barrel is fine. If you don't care about anything other than "it goes bang" and accuracy & precision are irrelevant, the factory barrel and spring swap is the cheapest way to get there.

 

[brucecrain]

Thank for the info. Looking in to Sig X-change slide