That looks good, nice and even gap all the way around.
Next, bring it into battery (cylinder locked into frame and cylinder locked in the cylinder notch) and use a light as best possible and look down the barrel to see if you see any of the cylinder. You should not see anything except a nice clear path from the muzzle to the recoil shield. If you have a .38/.357 range rod, insert it, it will tell you if there is any misalignment.
Then cock the hammer and pull the trigger and hold the trigger back and look at the barrel again to see if you see anything out of the ordinary. Also, while you have the trigger held back, grab the cylinder and try to rotate it to see if there is any play in the cylinder notch and the cylinder latch.
If you don't see/feel anything out of the ordinary, take it out and shoot some lead bullets (standard 158 gr round nose will work fine or whatever you have on hand). If you get the blow back, then open the cylinder and see if there is any evidence of lead shaving/building up on the rear of the barrel and on the left side of the forcing cone/barrel.