While I am not likely to convert my P229/357/40 to a 9mm, I was just wondering tonight exactly what is required! I know this topic has been discussed in the past, but for whatever reason I'm unable to find threads covering my specific questions, so here goes:

My P229/357 is a non-railed version with what most folks call a "Legacy Slide". I also have a .40 S&W barrel for it in the event I wish to shoot that caliber instead. I got to thinking about the possibility of converting it to 9mm temporarily for cheaper target practice, so I started wondering EXACTLY what is required, and whether it was worth the effort to do so!

I do know that a new recoil spring and magazines would be mandatory. It would also be a good idea to change the front sight from a #6 to a #8, but not completely necessary like different recoil spring and mags would be! So here are the things I'm unsure about...

1. Is a simple switch to a 9mm barrel for the P229 sufficient, or is a "conversion" barrel required?

2. I've read that this change requires the use of a 9mm locking block, so will the 9mm locking block be okay if/when I go back to .357 SIG/.40 S&W, or do I have to swap out the locking block every time?

3. Will the slide/extractor function properly with the 9mm round, or will I experience problems with the 1mm diameter difference?

I feel like I'm missing something regarding questions, but that's all I can think of at the moment. Thanks for your help on this subject!

Just buy a 9mm conversion barrel from Bar-Sto or other. No change to locking insert is required. 9mm rounds will feed reliably from 357/40 magazines. Recoil spring change is not always needed. I have fired my P229s using the conversion barrel without issue.

The purpose of the 9mm conversion barrel rather than a factory 9mm barrel is so that the 357/40 locking insert can be used.

Sometimes 357/40 magazines work with 9mm ammunition; sometimes not. If purchasing 9mm 229 mags, get the wider -1 type rather than the older ones intended for use with the original 9mm P229/P228. The narrow ones may work, but there’s no reason to not use the proper ones unless you have a bunch of the older ones.

Sometimes 357/40 recoil springs work with 9mm ammunition, especially hotter loads. They may not, however, with the typical loads used with wimpy 115 grain training stuff.

Changing a front sight from 6 to 8 will move the point of impact by only about 2 inches at 25 yards, and less at closer distances. Is that really necessary for the type of shooting you will be doing with the gun? I don’t worry about sight changes when swapping between 357 SIG and 40 S&W.

Many people have made the type of conversion you’re considering, and I have never seen a report of failures due to not changing the extractor.

Sometimes --minor fitting of the feed ramp is required. You drop the conversion barrel in. It may hang up on the feed ramp.
Some barrels drop right in. Some barrels hang up on the corners of the feed ramp.

I’ve been successful in using conversion barrels in my 229 and 239 as well as my G23. Never had a problem with any of them and all I did was use the conversion barrel, no other changes

I have a 9mm Barsto conversion barrel for my .40 P229 (like yours, mine is old-school, pre-rail with a legacy slide). The conversion barrel dropped right in, no fitting required.

The Barsto barrel is great quality, and extremely accurate. It feeds reliably with the .40 extractor, and even from the .40 mags (although the rounds are a bit "looser" and rattle a bit more than the .40). I haven't noticed a need to change the sights, either. While it has been reliable for range use in this configuration, I swap it back to the factory .40 parts for carry.

There are two negatives I've noticed. One is the price...iirc, mine was $225, which is kinda painful for a handgun barrel. Second, the Barsto barrel has a very tight throat. If you shoot factory ammo, it won't be an issue, but it's something you'll have to be mindful of if you reload, and use short, narrow ogive bullets.

Thanks for all of the helpful responses! It appears that I'll start with a simple 9mm conversion barrel and see if any other changes need to be made.

Thanks again!!!

I have had quite a few of the barsto conversion bbls in the past and just used the 9mm spring and 228/9-9mm straight sided mags with no issues. This was all before the standardization of the frames to the 9mm “-1” mags. Since the -1 mags have been created i have always kept a supply around.

Several years ago the market was flooded with surplus p228-9mm police trades that had everything but the frames sold as “parts kits”. The condition was that the frames were destroyed so the kits were plentiful and reasonably cheap.

I purchased one to use as a 9mm conversion for any of my p229-357/40 guns. To use the 228 parts slide on the 229-40/357 the 228 locking block also has to be used.
The parts kit i received showed lots of bbl wear so i picked up a new 228 bbl.

While the barsto conversion bbls always performed well with no issues and the sights were good enough i just liked having the 228 slide, bbl, recoil spring, guide rod and locking block assembly with the 229-9mm bottleneck mags as my conversion bbl assembly.

My only regret which i new would be the case at the time was not buying more on the 228-9mm parts kits when they were plentiful and cheap.

The 9mm conversion bbls, 9mm spring and the 229-1/9mm bottleneck mags are the way to go imo. As mentioned some of the bbls need fitting and some don’t.

While i have personally never owned or used one of the Lonewolf converion bbls many here have reported using them with the same reliable and accuracy results as the barstos at a cheaper price point. Which if i were needing a conversion bbl today is probably the way i would go.