I have a P229 in 40S&W, I believe I can go to a 357 SIG with just a barrel change and spring. My question is can I also go to a 10mm with just a barrel and spring, I guess I'm wandering about the extra power generated by the 10 and the 229s ability to stand up to it. I think I would need a different slide to go to a 9mm is that correct? I really doubt that I would go down to a 9 anyway, just curious. I have a lot of nice handguns but that sig 229 is as accurate and reliable as any of them. Thanks

If for no other reason, the 10mm Auto cartridge would not be usable in the P229 because its overall length is too great to fit into the P229 magazine. In addition the Grayguns conversions and then the factory 10mm pistols were based on P220s with steel frames. It was evidently thought that aluminum frames as the P229 has were not strong enough for the 10mm cartridge.

To convert a 40 S&W P229 to 357 SIG requires only a new barrel. Magazines and recoil springs are the same.

Converting a 40 229 to 9mm is more complicated. Current 9mm P229-1 magazines are evidently sized to fit the wider 357/40 P229 magazine wells, but the original 9mm and 357/40 P229 locking inserts were different, so a simple slide and factory barrel change wouldn’t work. I don’t know all the details about such a conversion today, but many users did convert from 357/40 to 9mm with an aftermarket conversion barrel.

Thanks, the 357 Sig is what I'm most interested in. RIA sells a 10MM 1911 for about what the conversion would cost probably and I'm not sure I even want a 10MM. If I want to get that serious, I'll get the 41 Mag or 44 Mag out. I guess the 357Sig barrel doesn't need to be fit ?

No, its just a "drop in" the barrel and "go".

As sigfreund stated, you just swap the barrel and you can use the same magazine for .40 or .357Sig rounds. No fitting required.

Just make sure you only shoot the 357Sig from the 357Sig barrel and vice versa.

quote:

Originally posted by glider:
I guess the 357Sig barrel doesn't need to be fit ?

I have actually encountered a factory 357 SIG barrel or two that was a tight fit in the 40 slide. It shouldn’t require any fitting, but until it gets broken in a bit, it might be hard to cycle by hand.
I have found the best “fitting” is to get the gun assembled with the 357 barrel, ensure the slide will go fully into battery even if it takes some pushing, and then shoot the gun with the new barrel. Any tightness will then loosen up to normal.

Thanks!

If I understand this correctly, the 9mm will not work if 'dropped-in', regardless of recoil spring?
Would I have to buy an entire 228/229 top-end in 9mm?

If you have a P229 in .40 or .357 Sig and want to go 9mm with that pistol, get a Bar-Sto 9mm semi-fit conversion barrel and 9mm magazines.

You won't need a different recoil spring, but the Bar-Sto barrel will need to be carefully fitted to avoid damage and ensure proper cycling and accuracy.

I had that done with my P-229. SigArmorer Robert Burke only needed to do a tiny bit of fitting the Bar-Sto barrel and the pistol runs like a champ.

Thank you, that sounds far less burdensome.
I appreciate it.

quote:

Originally posted by snoris:
If you have a P229 in .40 or .357 Sig and want to go 9mm with that pistol, get a Bar-Sto 9mm semi-fit conversion barrel and 9mm magazines.

You won't need a different recoil spring, but the Bar-Sto barrel will need to be carefully fitted to avoid damage and ensure proper cycling and accuracy.

I had that done with my P-229. SigArmorer Robert Burke only needed to do a tiny bit of fitting the Bar-Sto barrel and the pistol runs like a champ.

Thank you snores for this info.

I’ve been looking for a while at the conversion to 9mm capabilities &
read somewhere going with the .40/.357 slide would not work due to the size of the breechplate being larger to accommodate a larger shell.

It was advisable ( fr this source)to get the 9mm slide too…I suppose for the slightly smaller breechplate(?)

POA and POI for 40 differ from 357. Adjust sight picture.

quote:

Originally posted by 4MUL8R:
POA and POI for 40 differ from 357. Adjust sight picture.

Correct.

Interestingly (well, at least to me as I'm easily amused), the reason for this may not be entirely apparent until you think about it, Why would the flatter shooting .357 hit lower than the slower, heavier 40? The answer lies in the 357 Sig round being considerably faster than the 40, and thus spends less time in the barrel.

Immediately following ignition, the barrel and slide will be moving back together for a short distance, in relation to the frame, during JMB's ingenious short recoil action. The barrel chamber end is also moving downward in relation to the breech to affect unlock. This has the same affect on the projectile, still in the barrel, as if the muzzle were moving upward. The faster .357, spending less time in the barrel, will have its POI less affected by this barrel tilt phenomena than the slower 40. Thus, as noted, shooting .357, in a gun sighted for 40, will see the .357 POI different than the 40 POI for the same POA. The 357 will hit lower.