Need Help! Echo 1 M4 Stag-15 Series

I have had this problem for a long time and I am wondering if anyone had a similar problem and fixed it. When I try to pull back the delta ring to open the battery compartment it takes great force. I have to pry it open with an army knife because I cannot do it with one hand. It feels scratchy when I am pushing it down with both hands and sounds sorta like rusty and old oil. I have tried lubing it but its the same problem. Anyone know whats going on?

I have the gun, under the delta ring, there is a huge spring, which I found out the hard way by removing my delta ring. *Note, to prevent what I did, DO NOT TURN THE DELTA RING WHILE PUSHING IT BACK*

Any hoo, it seems like you need to put some ol'WD-40.
Put some of the ol' WD-40 on it, wait a few minutes, then try it again.

is the Stag -15 M4 plastic? because my experiences have told me that WD40 is a big no-go with plastic. silicone lubricant will work better if it is plastic.

noo
jarhead no listen to what I said
Under the delta ring is a METAL SPRING.
It might be old and rusty.
Try spraying WD40 at it.
Just get the red tip nozzle, point it under the delta ring, and PRESS THE BUTTON!

i'm terribly sorry; let me elaborate.
does it have a plastic body?

if you hit any plastic parts with the WD-40, it's gonna get "Watch your language" up.

Yes it does.
Okay, now that I've looked at it, it does have a plastic body.
Get a tissue, and spray WD40 at it.
Carefully wipe the metal spring without removing it.
This does require removing the delta ring off.
If you don't know how to take it off or put it back on, PM me, and i'll give you pics, and a very detailed explanation to take it off.

No it does not have a plastic body. The delta ring is metal too. I do not know how to remove it and because if I did I would have