Can anyone answer for me a few questions.

1. When threadind a barrel on a CZ550 do you need to leave a shoulder to butt against the receiver? I'm thinking that it isn't nessasary since the action looks very simular to a C-Ring Mauser 98 action.

2. Anyone know the thread sizes for the barrel/receiver?

CZ factory barrels have a shoulder and are set up for a 0.002 crush fit at the breechface. The barrel thread is M28x2sp3 for the magnum and M26x2sp3 for the '06 bolt face.

If this helps at all, Model 70's and Model 700's don't have an inner ring and stop against the receiver face. The CZ with it's inner ("C") ring would probably be OK with no front shoulder as long as the threads were tight going on to prevent any lateral motion. In my opinion, I would at least put a minimal shoulder to butt the barrel against. As Head Trauma said, you make the barrel shank .002" shorter than the receiver face to inner ring measurement and allow for a crush fit to take up the .002" and have the barrel touch both the inner ring and the receiver face. Just good insurance!

Thanks for the help. I'm trying to use a Douglas barrel that I have the OD of the barrel is 1.060" and I think the threads come up to 1.015" OD. I'm thinking that would give me .045 for the crush fit your talkinf about. Depending on how accurite my verneers are.

I'm trying to save a few hundred $$$ and have the gunsmith who will do the install use the barrel I have.