To the best of my knowledge and recalling a conversation with Willard, the P225a1 locking block would be the same as a P239. That being said I believe they are caliber specific but don't quote me on that. The P225 locking insert would be it's own animal, but someone with more experience on that particular platform would be able to tell more.

Edit to add: From what I can tell, the P225 locking block is specific to the P225. I am not sure of the dimensions.

 

This thread might help some

https://www.sigtalk.com/threads/p225a1-parts-sourcing.459493/?post_id=6593479#post-6593479

 

I should have elaborated better, this was for a 226, but it was much too short, so I tried to find the closest locking insert I could to its size. The 225 is the smallest I have.

 

Ah, gotcha! If it is of any help, I checked the two 40 S&W original P226 guns that I have and they do not have that "40" marking on them. That being said, I went down the rabbit hole on locking blocks a few years ago and I think my head is still spinning understanding all of the changes Sig made to them over the years. My interest was mainly on the P220 guns however.

 

Thanks for checking. I believe sigs locking inserts are the same for the corresponding pistol regardless of caliber.

 

Should be an older P229 .40/.357 locking insert. Remember 9mm P229’s used to use the P228 locking insert (these were stamped 29). Current P229’s all use the same locking insert (hence the P229-1).

That’s a machined insert. All new locking inserts are MIM.

 

Should be a P229 .40/.357 locking insert. Remember 9mm P229’s used to use the P228 locking insert. Current P229’s all use the same locking insert (hence the P229-1).

Thank you.

 

I have a 229 with 40 stamped on it. I can not get a 357 barrel to go into battery on that 229. However, other 229's with no #'s (40, or anything else but maybe dots) will accept a 357 barrel just fine. My guess it's for a 229.

 

I got a p229 with the "40" stamped on the locking block insert and it will use my 357 sig barrel i picked up fine. Have you tried switching slides to make sure its not a slide lock up issue and not the frame??

 

I don't know anymore. I put a nice nic in a brand new 357 barrel attempting to rack the slide.
I used to think I was pretty smart. Now I just think I'm on borrowed time.