i did have to send the gun back to umarex for barrel warranty and it had the velcro stirps on the riser. they gave me no issues what so ever about things being modified. i've heard some makers would not honor warranty work when mods are done.
Probably more questions than answers about the Gauntlet....but did post:https://www.gatewaytoairguns.org/GTA/index.php?topic=175947.0