I just fill mine with sand.... It's alot easier that way Though the weight come out heavier than the real one. However, since I don't have IIIA on rest of the part the complete weight is only few hundred grams off the real vest (IOTV)
One thing I will say, you gotta watch your weight distrubiton otherwise you'll look crap (if you have hydration system, might want to consider keep the back plate lighter or empty)
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