When I select to infuse one of my EGtW firearms(Palm Pistol/Pepperbox/Bad News/etc.), only the Enhanced Weapon infusion works while the Repeating Shot will not show any options for any aforementioned firearms except the DMG firearms.
That is correct. The Repeating Shot infusion requires that the weapon has the ammunition property with all of its associated rules. The Exandrian firearms use different rules, and so therefore do not have that weapon property. Yes, they use ammunition, but they do not have the ammunition rule.
When I select to infuse one of my EGtW firearms(Palm Pistol/Pepperbox/Bad News/etc.), only the Enhanced Weapon infusion works while the Repeating Shot will not show any options for any aforementioned firearms except the DMG firearms.
That is correct. The Repeating Shot infusion requires that the weapon has the ammunition property with all of its associated rules. The Exandrian firearms use different rules, and so therefore do not have that weapon property. Yes, they use ammunition, but they do not have the ammunition rule.
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