I should be getting my new rail setup here Monday or Tuesday and I'd like to install it right away. The Grenadier Precision ARM-R says it can be installed in 5 minutes without any special tools, but I take it that's on an AR15 that's had the delta ring/spring and retaining cup next to the front sight base removed (I dunno what the proper term for this retaining "cup" is). Since I don't have any armorer's tools and a vise, I take it I'll just have to cut the delta ring and handguard retaining cup off? How can I loosen/remove it from the barrel nut before I cut it? And how do I loosen/remove the handguard retaining cup next to the front sight base before I cut it too?

I tried searching for a guide but came up empty handed. The US Army manuals and similar documents that I looked at didn't discuss removing these (since I guess they expect only certified armorers to do it).

Thanks for the help!

If the rail clamps around the barrel nut then cutting the delta ring (I think thats is what you are calling a cup) off the uppers is the easiest way.
If you have a dremel tool with a cut off wheel it will take a couple of minutes to cut through the aluminum delta ring. Mask the front of the upper receiver with a few layers of heavy masking tape or duct tape in case you slip. After you make 2 cuts through the delta ring it will come off and revel a spring which you will have to also cut. Then there is a snap ring you can pop off with the correct pliers for them or a couple of pointy tools (careful as those clips enjoy making you gore yourself with out the proper tool).

Thanks for the info!

By retaining cup though, I mean the round thing attached to the front sight base that holds the handguards on the rifle at that location. I didn't notice any pins holding it up next to the front sight base. It has to be removed because it blocks access to the thumb screws that allow the top of the rail to be removed.

Quoted: Thanks for the info! By retaining cup though, I mean the round thing attached to the front sight base that holds the handguards on the rifle at that location. I didn't notice any pins holding it up next to the front sight base. It has to be removed because it blocks access to the thumb screws that allow the top of the rail to be removed.

Pull the gas tube, knock the FSB off, throw the handguard retainer on the bench, put the FSB back on, reinstall the gas tube with new pin... the retainer is just trapped between the FSB and a small shoulder on the barrel.