I just made a 357 SIG barrel for my P-06 this last week.
I test fired it Saturday.
I did go to gunsmithing school 30 years ago so I am a bit above amateur, but it wasn't too hard.
I was able to do the work on my beat up old Atlas 12" lathe, with a 4 jaw chuck..
I started with a 9mm barrel for the P-01 or PCR.
I got the chamber reamer from Brownells on sale for $60 and the Go/No-Go gauges from Manson for $30 each.
You have to be very careful when reaming the chamber.
It is very very easy to go too deep and destroy your barrel.
To get close on the lathe I measured how far a 40 S&W cartridge stuck out of the breach end of it's barrel and used that as a target for my barrel.
Once I was getting close a had to pull the barrel from the lathe, assemble the gun and try the Go gauge.
The 3rd time it locked up perfectly.
The trick to using a 9mm barrel is silver soldering on a collar to index on the larger barrel bushing on the P-06 slide.
The 9mm barrel is 0.500" OD exactly, while the 40 S&W barrel measured at 0.544".
I wanted to see how tight I could get the barrel to the 0.552"ID bushing so I made it too tight and them stepped it down gently until it fit perfectly at 0.549".
The collar is 0.675" long and tapers to the muzzle.
The only issue I had at the test fire was the Speer Lawman 357 SIG ammo was a tiny bit too long for the CZ mag and tended to drag it's nose as it fed.
This led to many jams until I learned to make sure I seated the ammo all the way in each time, then it fed fine.
I will be hand loading for this and can manage my OAL precisely.
Recoil was about 10% stronger than 40 S&W from the same gun.
Accuracy was stellar.
I'll try a stronger Wolff spring to see if it cycles a little smoother.
Overall I am very pleased with the outcome.https://www.flickr.com/photos/129065511@N02/26803648055/in/album-72157667736963411/