If you're talking about pistol barrels; buy a cheap case (rifle or large pistol case). Make sure the case is deep enough to store two layers of guns. Go to the fabric store and buy some new foam layers and cut them to fit the shape of each barrel or each barrel with their scopes. This way you can stack two layers of scopes and lay them opposite each other on each layer. Depending upon how long or deep of a case you buy, you should be able to store quite a few barrels this way. Plus, you can always wrap them in a Bore Store while they're in the case....and of course, this makes them ready to take into the field or to the range. If you plan on taking them to the field of range in this case, you may want to invest in a nice case such as an SKB or a Pelican case.
I don't know if it's right or wrong but that's how I've stored mine for quite some time.
With carbine barrels, I just line them up along the inside of the safe and maybe Bore Store them in case they fall or bang into each other.