[beta678]

From what I've read and seen, the buffer tube should be Milspec, some airsoft stocks won't fit.

PS. Found some numbers for tank size and shots, apparently its relatively accurate.

Gas Air Efficiency on HPA / CO2

Official Numbers from Tippmann.

Shots per source:

12 g Co2 = 80 shots
9 oz Co2 = 1700 shots
20 oz Co2 = 3800 shots
68 cu in HPA @ 4500 psi = 4400 shots
48 cu in HPA @ 4500 psi = 3120 shots
48 cu in HPA @ 3000 psi = 1920 shots

(actual results may vary due to atmospheric conditions, tests performed at 72°F)

Though nothing on the 13/3000, dunno if scaling down the 48/3000 would be accurate but its about 520 shots if you do? Don't know much about HPA tanks so might be completely wrong.