I don't own a 365XL.....yet. But I found these today.
https://lakelinellc.com/shop/p365-magazine-fill-sleeve-for-use-with-15-round-mag-flared/
These sleeves fill that god awful gap the 15 Rd mags leave at the back of the grip. I've handled one at my LGS and it just felt wrong. I don't know the purpose of why SIG does this. It seems every other manufacturer with a compact or smaller size grip make a sleeve that fills the up grip.
With the sleeve.
I know nothing about them other than they are $15 and out of stock.
https://lakelinellc.com/shop/p365-magazine-fill-sleeve-for-use-with-15-round-mag-flared/
These sleeves fill that god awful gap the 15 Rd mags leave at the back of the grip. I've handled one at my LGS and it just felt wrong. I don't know the purpose of why SIG does this. It seems every other manufacturer with a compact or smaller size grip make a sleeve that fills the up grip.
With the sleeve.
I know nothing about them other than they are $15 and out of stock.