How to upgrade HK416 handguard

Hey so I bought the LDT HK416 and I was thinking about converting it to a CQB variant. Also wouldn’t mind changing some of the crappy nylon to metal haha.

So if I were to buy a 4inch hand guard , would I need to buy some sort of adaptor kit? What about the barrel what size would be needed for such a short handguard ? Is there any other parts that’ll need to be replaced to accomplish this?

Cheers

The 416 uses a different hand guard to m4’s because of the gas operated piston vs gas tube. The top rail sits higher to clear the pushrod. Your options are going to be very limited . If you use an m4 hand guard there will be a step down between the top of the receiver and the hand guard top rail.

Thanks for the response,
Ahh that is super annoying. Maybe I should build a M4 CQB blaster from scratch? Seeing as I would be changing most of the parts for metal.