Here's a .22 cal can I just built. The baffle is 1 inch x 7 inches. With the outer tube it is 1 1/8 inch in diameter. I made it the same way as the Whisper can above, but of course threaded it at 1/2 x 28.
Here's the completed baffle
The baffle and outer tube
After press-fitting the baffle into the tube--no need for welding with a precision fit