Things do go wrong with guns, it's true. Take this quote from an ad for a JR Carbine in 9mm which just went up today on the EE:
Or this from Youtube, a JR Carbine in .45 with FTF problems:
Or this short review/warning from a Canadian owner of a more recent JR Carbine. Chews up magazines, very fussy to maintain, gets very filthy with modest amounts of shooting. Says it's accurate which is cool. Charging handle came loose after less than 100 rounds with a live round stuck in the chamber at the range because he didn't have an allen key with him (allen key? for an AR-style rifle charging handle? HUH? what is this, a Browning .22lr pistol?). Anyway, see for yourself:
I could go on and on. Googling 'JR Carbine problem' brings up loads of results, same as checking the same for 'TNW ASR problem' or similar. Or just about any other gun really. Sometimes you get a lemon. Sometimes it's user error. Sometimes just a disagreement with a particular ammunition and a particular gun. I know airguns a lot better, and have for example seen one type of pellet which which spirals absurdly from a PCP rifle which will deliver slightly larger than pellet-diameter groups at 10 metres with a different pellet. I've no idea which of these or what other problem might be involved with the TNW carbine you have, but yeah, if mine was doing that persistently I'd probably feel like selling it too. Given my history with airguns though... it's more likely I'd keep tinkering with the mechanisms until it worked flawlessly. But not everyone is up for that, so by all means sell it. Maybe it'll work better for a buyer using different ammo.