I can attest that barrel suck is true..
I have 2 G3s one is the sg1 and the other is the sas version. I was having issues with the sg1 in regards to the mechbox, so swapped the front ends. what ended up happening was a gun that was shooting about 310fps with .2s ended up not even being able to launch a projectile far enough to hit the targets at the new old flag raider's chrony stations. this effect is discussed on this site, it's basically because the sas has a different cylinder (has air holes in it) than the sg1.