Iam new to this site and new to the .22 tactical rifles. I have a M4 carbine ordered and waiting for it to arrive. I have been looking at the mods and upgrades everyone is doing, and iam wanting to change the polymer handguard for a quad rail. I have searched everywhere and i seen someone saying the 6.5" carbine length AR15 drop in rails will fit with my delta ring system. Can anyone confirm this before i buy parts? Iam also looking to remove the carry handle and put a scope on it. I guess i should have ordered the m4 ops but i didnt know the differences until i already purchased the carbine.