I ending up getting an adams arms evo ultra lite  16" carbine upper for xmas.  It didn't come with any instructions or diagrams or anything so i was taking it apart just to see where the gas flows and where's i'll anticipate cleaning and lubing.  

In comparing what i have to the adams arms website, i see that their kits come with spring on the rear of the operating rod.  But i don't have one on my evo upper?

I see on the website that the upper recievers are drilled so it doesn't require a spacer bushing, but do i need to spring to help move the op rod forward during it's operation cycle?  I know the bolt will eventually push it forward, but i wasn't sure if i needed the oprod spring too?

My guess is i don't need it since the receiver is drilled to the proper hole size.  The spring is only used to keep the bushing in place while operating?  

I just built an upper with the Adams Arms .750 light piston system, 6.8 SPC Spec-II 16" Bison Armory SS Recon Profile barrel (OD Green gun kote) & a Sampson EVO 9-EX rail, which is very close to what you have and I installed the spring on my piston rod. The bushing tapped in from the inside of the receiver is usually pounded in with a mallet or hammer and the supplied installation rod to do the job. It says in their instructions that if the bushing is loose to use red lock-tite to install the bushing on the inside of the receiver and let it cure before operation, therefore the spring does not hold the bushing into the receiver. The spring is between the barrel nut teeth and the piston rod bushing on the piston rod going towards the piston gas block.The spring never really touches the slide-bushing inside the receiver at all.

There may be a possibility that since you are using the AA upper reciever that you might not need the spring on the piston rod but it seems like there should be a spring there to help the piston rod return back to the original position.

Sounds kinda confusing but thats the best way I can think of explianing it.

Yea that's what i was thinking.  An adams built upper doesn't need the bushing since it's already drilled for the proper size hole.  

So the spring pushes up against the teeth of the of the barrel nut? Because my upper definitely did not come with a spring.

Your rifle does not need the spring to operate correctly, but the spring keeps the rod from rattling. I would just call adams arms, they will most likely send you one for free. In the meantime, you can shoot it without damaging anything.

how do you like it...i'm just about to order one

Well i haven't taken it to the range yet, but so far so good.  It's very light weight and easy to point.  I have a spike's lower and PSA MOE lower builld kit on it.  It weighs 6.8 lbs total, maybe i'll throw up some pics.  

So far i like the handguard alot, it's comfortable to hold, and doesn't have the added weight of rails in places i'll never use.  I only plan on adding a light and front BUIS to the rails.  Fit and finish are very good.  The barrel is melonited inside and out, so is the piston group/rod and BCG it seems.  Looking forward to shooting it.  

Mine came from western sports, receipt in the box said it was $799 with free shipping(fedex).  Took 2 days for western sports to process the order and took 3 days of transportation from texas to pa.  Overall very satisfied with western sports.  

I'll hold judgement on the upper to until i shoot it.  I would stick with the carbine unless you need the extra sight radius and length for another $100.

http://home.comcast.net/~nesethkong/evo1.JPG
http://home.comcast.net/~nesethkong/evo2.JPG
http://home.comcast.net/~nesethkong/evo3.JPG
http://home.comcast.net/~nesethkong/evo4.JPG
http://home.comcast.net/~nesethkong/evo5.JPG
http://home.comcast.net/~nesethkong/evo6.JPG
http://home.comcast.net/~nesethkong/evo7.JPG

It does not need the spring to operate, but it is supposed to have a spring (smooths felt recoil), I would call AA tell them what you are missing.

Sounds like you are also missing a spring cup. Are you sure it dod not fall off
of the op rod?  It may be laying in the botton of the rail assy.

Definitely did not fall out, i was very careful in taking it out, i would have seen it fly out if it had any tension on it.  I also checked all around the handguard, nothing fell out or around there.  I also keep my workspace very clean and maintain all my guns on a large white sheet specifically for this reason, found nothing in the area.

It for sure didn't come on my gun from the factory,  the real question is was it supposed to on the EVO model or not?

I'll email adam's arms for the answer.

I just checked my Evo Ultra Lite and there is DEFINITELY a spring on the operating rod
I did want to add that I ABSOLUTELY LOVE my Adams Arms Evo Ultra lite...I am sure you will too!

Yes, please let us know what AA CS says about it. I was seriously considering this upper also.

oh sorry i didn't update.  AA customer service is excellent.  I sent them an email and an hour later i got a response asking for my address so they could send me the spring and bushing.  The next day it was in the mail through fedex.  :-)  I've always heard great things about their customer service so even if you buy their upper and it doesn't work, they'll make it right.

Glad to hear about their customer service. You will LOVE it!