On several of my clone rda's the barrel was too tight on the deck. Yesterday I found a solution. The rubber o-rings used on most rda's are standard, mostly the chord is 1 mm in diameter then there are various diameters from say 22 mm and getting smaller in 1 mm increments. If the barrel is too tight around the deck use an o-ring that is 1-2 mm smaller in diameter. By stretching the o-ring farther it will stand off less from the deck and the barrel will slide on and off more easily. This has worked on a couple of my rda's.
fasttech sells packs of rubber o-rings for e-cigs in the common sizes for a dollar or less per 20 of each size so for perhaps $10 it's possible to have most every o-ring size that might be needed to adjust tightness of rda parts that are set by o-rings. Found 69 o-rings (Product Type: O-rings) at FastTech - Worldwide Free Shipping
fasttech sells packs of rubber o-rings for e-cigs in the common sizes for a dollar or less per 20 of each size so for perhaps $10 it's possible to have most every o-ring size that might be needed to adjust tightness of rda parts that are set by o-rings. Found 69 o-rings (Product Type: O-rings) at FastTech - Worldwide Free Shipping