Decoding Lothar-Walther Website

I am looking at barrels found here: https://www.lothar-walther.com/gun-barrel-blanks/airgun-barrels/?p=4

Im having trouble decoding what the differences are in all these barrels, because for each barrel spec, there exists seemingly-identical products with different pictures for the same price.

1. What is a “blank?” It’s obviously rifled with a twist rate, so, the term “blank” is lost on me.

2. What’s with the “wind” icon in the second picture?

3. What’s with the “black doodle” in the third picture?



4. For slugs, would an UNCHOKED barrel be ideal?

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