also with the Echo 1 M4 RIS what bb should i use that will be the most accurate?
Try them out, it's different for each gun.
I've seen guns that shoot perfectly for the longest range with .20's (KWA SR-12, I think it's a fluke gun though)
I use .28's in my SR16 shooting at 510ish fps with .20's and they're just barely heavy enough to keep the shots accurate.
I've found that you can shoot .23's out of almost any gun and have stable, somewhat high fps shots. They're great until you get up around 410 or 415fps (with .20's)... and then you need .25's or higher.
You'll get plenty of people that say you should go way high (.28's in regular guns), and some people (like me) that say only go as high as you need to (I run .20's up until around 375fps and then move on to .23's or .25's, and move up slowly until I get a round that's stable in the gun).
Long story short... My experience... Try out the different weights/brands and see what works for you. If it's a completely stock Echo 1, Unless it's one of the hotter ones (Most echo 1's are around 350 fps, though some are over 400) you will be fine running .20's... and likely won't see much of a difference moving up to .25's other than a significant decrease in velocity.
And the batteries, he was spot on. mA h rating and your particular gun, as well as your play style, and how long it's been since you've charged it, and the quality of the battery are the parts that affect how many shots you get from a battery. Personally, I haven't run out of battery in a day unless I was holding full auto for extended periods or using sub-par batteries.
