Info of value: SAAMI dimensional standards

Chamber neck diameter: 0.3789” +0.002”
Cartridge neck diameter: 0.378” -0.008”
Bullet Diameter: 0.357” -0.003”

0.9 thou isn’t much clearance, but enough. But a minimum spec 0.3789” chamber with 0.0378” case neck around a 0.357” bullet with 2 thou neck tension... 0.378-0.357+0.002 = 0.023”, divide by two, that’s 11.5 thou case neck thickness. If you buy brass with 12.5-13.5 thou wall thickness, you have to either ream/turn necks or size bullets.

Alternatively, a maximum spec chamber at 0.3809” less 0.0009” clearance, 0.380” cartridge neck, less .357” bullet plus 0.002” tension gives 12.5 thou case neck thickness. Still thin.

Sizing to the 180 HotCor to .356” would certainly chamber - only pulling it down to .357” should fit, but .356” absolutely should unless the barrel chamber is out of spec.