OK so as someone that has been on the hunt for a FF handguard that will work with the XLP I bought a Midwest Ind. Gen 2 SS.  After getting it together the barrel nut will not clear the spring bushing at all.  I then removed the spring bushing leaving only the spring, and used a sanding barrel to clear a shallow channel into the barrel nut.  With that everything seems fine.  I'll be taking it for its maiden voyage this weekend so I'll report back how it works, but based on function check I believe everything will be fine.  I contacted AA about leaving the spring bushing off and while they haven't tested it, they said they expect the only possible downside might be a shorter life for the spring.  Being only a few dollars I can live with that, and frankly I probably don't even need it for function and may try removing it and seeing how it runs without it.

As an aside, in another post here, someone has asked about "smooth" rails that will work.  An AA rep said the AP Customs carbon fiber rail would and I went with that originally, only to find out it will not clear the top of the gas block and the piston.  I think it could be clearanced from the inside but being a plastic based product probably would not hold up well without major clearance, and at that point it's no longer "guarding" your hand.  

So... the purpose of this post, and I hope it sticks around, is to share what has worked and what has not as AA has basically nothing to share yet, so as an AA fan I'm trying to help others out there by centralizing the list of "gos" and "no-gos."  So, now it's up to you, the hive, and hopefully AA will chime in as well as they come to find compatible handguards with the XLP system.  

My suggestion is I will start a "go" list in my next post, and a "no-go" list in the one after that.  As you find what does and does not work please quote the appropriate list and add to it, with any notes like "with mods" as I describes above.

So that's it... GO!

the "GO" list

Midwest Industries Gen 2 SS will work with clearance created in the barrel nut for the op-rod spring and running without the op-rod spring bushing.

"NO-GO" List

AP Customs Carbon Fiber FF handguard is a nice piece but will not clear the op-rod or gas block.

A "GO LIST" should be a list of ONLY rails that will work without modifications to the rail or barrel nut to make it work.

If you have to make mods to a rail or barrel nut it should go into a "Modifications" required list.

A lot more rails can work with piston systems if we have to modify the rails. A useful list would be set in three categories.

Troy Industry Rails won't work because they need to rotate to secure onto the barrel nut, its impossible as the piston cylinder etc is housed in the milled out picatinny section.

Troy rails that require rotation to seat the rail to the barrel nut as there is no pass-through for the op-rod with the XLP

Samson rails are GTG.

Now that's what I'm happy to see!  WTG AA.  Let's keep it going...

OP or AA rep, can you please post pictures of the modification to the Midwest rails? I have 3 MI rails, all SSK. Thanks in advance!

Yeah I wish I'd taken pictures before I put it all together... long story short though once you have the nut properly torqued you have to dremel out a little channel on top of the nut right up to the "teeth" of the nut.  You also have to put a flat on the bottom of the op-rod spring bushing to allow it to sit right up against the teeth of the barrel nut.  I did it all with a sanding drum but it's slow and tedious with the bushing.  If you have a belt sander and a pair of vice grips it would be much faster.  Just make sure the op-rod isn't at any sort of angle.  If you have to flex it at all to get it to go onto the male part of the piston/gas block you haven't gone far enough.

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It will only work if you put the rail on first then finagle the piston kit in while the rail is installed because you can't have the piston kit on and rotate the rail in place, then once you get it all set up you have to cut the rail out of the bottom into order to get all three set screws in. If you modify your rails in anyway the rail company will not cover them under warranty if something did happen.

You have to modify the rail TacBlade

Got mine towork.

Warranty issues aside I wonder if it would be worth the effort to weld a boss to the MI barrel nut to support that collar better.

The Samson Evolution rails are what the railed AA rifles come with.  Personally, I love those.  They are stout, lightweight, and pretty simple to install.  Plus, they are very reasonably priced.

Did anyone find a smooth, free float handguard that worked without mods besides the Samson Evo?