Socom Gear DD RIS install in CA
 

I'm planning on getting the CA M15A4 blowback: http://www.thewarstore.org/airsoft/a...-blowback.html
I'm also interested in getting a socom gear DD RIS rail. http://www.redwolfairsoft.com/redwol...l?prodID=26246
I've read that you may have to rethread the upper receiver, which is something I'd rather avoid just to install a rail set. Does anyone know if I'd have to rethread the CA or is this procedure required only on certain M4s?

Redwolf says that the only receivers that don't need to be rethreaded are Systema and Prime. But I was wondering if anyone has come across a receiver that didn't need rethreading either.