What upper/barrel? If its a frankenstein build with cheap parts, then I'd disassemble and make a new one if you're on a budget (if you're not, then I wouldn't even consider asking this question, so I assume that you are - like the rest of us 
).
If its a quality name-brand barrel/upper combo, then you might be better off selling and replacing or buying another upper and keeping both (either way, I'd keep it together instead of separating since it would most likely be more valuable together).
If its a frankenstein build with hand-picked high quality parts, then I'd keep it for sure - it takes too long to find "the good stuff" for replacement parts to get it back.
).If its a quality name-brand barrel/upper combo, then you might be better off selling and replacing or buying another upper and keeping both (either way, I'd keep it together instead of separating since it would most likely be more valuable together).
If its a frankenstein build with hand-picked high quality parts, then I'd keep it for sure - it takes too long to find "the good stuff" for replacement parts to get it back.
