I've got a friend that I'm redoing a 450 bushmaster upper for that I own.  I'm kind of going backwards as he wants to install a non free floating Magpul moe handguard.  Currently, the rifle is fitted with a low profile .750 gas block, midwest handguard with it's barrel nut, and a mid length gas tube.  I haven't used a Delta ring type retainer in many years and have no idea how to set this upper up for this handguard.  I imagine I need a delta ring assembly with barrel nut.  The gas block kind of has me confused though as the gas block is what holds the front of the handguard in place.  What gas block do I need and will a standard front handguard cap work?  He definitely doesn't want any type a a post front site as the rifle will have a scope.  TIA.

This https://www.brownells.com/rifle-parts/gas-system-parts/gas-blocks/ar-15-gas-block-front-sight-prod21446.aspx

Later tonight I will did through my parts been.  As many free floats i have put on my rifles I should have a few rings and front plates.  You will still needs a front base sight though.

Send you IM regarding parts.

You will need a Delta ring assembly and a front handguard endcap. The muzzle device will need to be removed followed by the gas block and gas tube (still attached to the gas block) will have to be removed, then the barrel. If it has a standard barrel nut, that is good. If not, you will need a standard barrel nut as well. The barrel nut (if not already in place) will slide down over the barrel and rest against the barrel extension. The Delta ring assembly will then need to be installed. Once this is done, you can install the barrel, making sure that the barrel nut and Delta ring assembly are aligned with the gas tube hole in the upper receiver. You will then slide the endcap on followed by the gas block/gas tube combo. Make sure that the gas block is aligned with the gas port and tighten. Re-install the muzzle device and tighten. You are now ready to install the mid-length MOE handguard.

There are a plethora of reasons why I wouldn’t do that.

I know how to do the swap, just need the right parts so it will all work.  He definitely doesn't want to use a gas block with a flip up sight as the gun won't have any buis.  If anyone has all the parts they want to sell, please contact me.  I'm sure someone does as this is what most take off.  It's what he wants so it is what it is.  Already have the gas tube.

I got nothing. I can’t find the ring I had.

The gas journal probably isn't cut for a handguard retainer.

Trying to be 100% sure of what you want:

(1) a low profile AR gas block (low profile w/out FSB or rails.)
(2) a forearm retainer plate,
(3) a MOE carbine handguard (or is it midlength?)
(4) Standard AR barrel nut
(5) Delta Ring & Spring.

You already have a carbine length gas tube you plan to use.

does he plan to trade in the current set up, or he just wants to buy parts.

Thanks for the clarification!

BIGGER_HAMMER