Y'all make it harder than it needs to be. I have a 5' Cold Steel Big Bore, and the 2' Extension. All I do is remove the mouthpiece, and endcap, then take a 7' piece of string, paracord, or sisal cord (or even fishing line...), clip a pinch-on fishing weight to one end, tie a 12 ga. shotgun swab to the other end (with a slip knot), and soak it in alcohol (rubbing...). Holding the blowgun vertically, I drop the weight down the barrel, which pulls the string after it. , Then, I grab the weight at the other end, and slowly pull the swab through. If necessary, I change the swab and repeat the process several times, until the swabs comes out clean. Then, I run one more dry patch through it, and then one more sprayed very lightly with Break-Free, or WD-40. My bore stays clean as a whistle. It works on my .40 cal, also. I just use a smaller .40 cal swab. I take the Break-Free soaked patch loose from the string, then finish the job by wiping the outside surface with it. I let it set for a few minutes, then wipe off the excess with a clean swab. Or, sometimes I will wipe the outside with a silicone-soaked gun cloth.
I avoid using hot water because of the danger of it warping the barrel.
Keeping the barrel cleaned and lubed helps your speed. Last time I chronographed mine, I was getting 310 fps with bamboo darts, and 293 fps with the steel spearpoints. The slowest was the large broadheads at 247 fps. This was using the 'Tee' blow method. The 'Whoo' method resulted in slightly slower speeds, but the dart seemed to retain more energy at the target. Probably due to a longer, more sustained acceleration down the barrel. When hunting, I usually use the 'Whoo' method, because it is smoother, and has less chance of barrel jerk. It sort of like squeezing the trigger on a firearm, as opposed to jerking it.
By comparison, my compound bow set at 55 pounds, with a 26" draw gets 280 fps with Easton xx75 Gamegetter arrows.
Needless to say, I Iove my blowgun.