Dreamline Gen1 vs Gen2 Question

I am the proud owner of a Gen1 Dreamline .22 tactical bottle version and would like to try the 21/23 gr slugs.I have been told that the Gen1 is only really good for shooting pellets because the valving is smaller than the Gen 2 .Just wondering if any of you Gen1 owners have any info to add with your experience.By the way I have the powder plumun installed and a 600mm barrel on order.Your comments please.
 
When slugs are shot out of a barrel they like they do not have to be traveling at high velocities. My .25 Impact 700 slug liner shot several of the NSA and VK slugs at MOA at 100 yards at 740fps and the JSB King heavies shot just as well. They did not do well past 125 yards though. It just depends on the barrel. 

Still most slugs are meant to be shot at higher speeds and longer ranges and for the most part they do better that way.