I use an F4 illustrator w/ a 14" barrel & expansion chamber
I would recommend a longer barrel.
This product is durable, and very CO2 efficient. The volocity is very consistant from shot to shot. Thi gun is also very accurate. In two games I shot my brother twice with only three paintballs. Both shots were at least 50ft away. Great gun!
The gun seems to lose alot of CO2 when unscrewing the tank. Might just be my O rings.
This is a great buy. It's perfect for playing with friends and if you wanna bring it to a real coarse it will shoot better than most guns people have.