Here's a photo of mine showing the same gap. If I hold the gun up to light, it's more apparent but you can see the top of an obvious gap in the photo:
Looking closely at it in person, it looks to me like that area of the barrel, the rear face of the top rib, may be slightly angled away from the frame, perhaps by design. Or maybe it's the upper front face of the frame that tapers slightly away from the barrel.
As for the cylinder gap, you can measure it with feeler guages. If you don't have those handy, try to take a good look at the gap holding the gun up to some light to see if the cylinder face and the face of the cone are at least parallel.

Looking closely at it in person, it looks to me like that area of the barrel, the rear face of the top rib, may be slightly angled away from the frame, perhaps by design. Or maybe it's the upper front face of the frame that tapers slightly away from the barrel.
As for the cylinder gap, you can measure it with feeler guages. If you don't have those handy, try to take a good look at the gap holding the gun up to some light to see if the cylinder face and the face of the cone are at least parallel.
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