I have been away from this forum for a while busy with life and a new granddaughter in the family, but I have recently picked back up on my XM177E2 build. I was about to pull the trigger on a complete H&R gray XM177E2 upper but they went out of stock. But fortunately my email notification rang with a H&R gray stripped blem upper, and I jumped on it (out of stock right after I ordered). I received it today and honestly I cannot find the blem. The gray matches up really well with my lower H&R XM177E2 purchased over a year ago. If I can remember how to post photos, I will post a photo. I have all the parts (Luth-AR teardrop foward assist assembly, gray H&R charging handle,
H&R M16A1 ejection port cover assembly, H&R gray delta ring, PSA AR15 snap ring, PSA AR15 weld spring, H&R 6 hole drop in carbine handguard, H&R XM177E2 flash hider, and the retro H&R XM177E2 aluminum 2 position stock). I
just lack the M16A1 rear sight assembly and the barrel assembly. The rear sight assembly is out of stock with PSA currently and I am still considering the H&R 14.7 barrel and having my gunsmith cut it down.
I obtained a 12.75” barrel, and am going with the long flash hider/pin-weld on mine.
If I can ever find time to put something together.
KAK has the faux moderators and if you go for the shorter look you either need p/w or SBR paperwork.
I have the H&R faux moderator ( flash hider). I am waiting to see if the Senate includes the SHORT Act in the Big Beautiful Bill, but I am not opposed to going the NFA SBR route if I have to.
Where can I find the rear sight assembly for the M16A1 upper?
you’re right the colors match very well. it looks like you’re well on your way with this build. keep up the good work, and welcome back. we’re glad you returned!
Brownells and Midway USA both show A1 rear sights in stock. Brownells lists two different options, is either one correct for your build?
This one is labeled “retro”?
I am still trying to decide which A1 sight assembly to purchase.
KAK and Luth-AR don’t necessarily have the best reviews. Linemount, TNTES, and Retro Rifles have them, but they are black and not gray color. Any more advise is greatly appreciated!
KAK has always been gtg for me.
Does anyone know where i can get a retro complete upper with the triangle handle been able to find some with 20" barrels but i was hopping for 16"
Doubtful you will find a 16" retro.
welcome to the forums @Albarranadolfo we’re glad to have you. I dont know if anyone is producing the 16 inch but H&R is where i would look first.
Psa makes one but they always seem to be sold out this last time it was in stock i just couldnt fit it in the budget 
https://palmettostatearmory.com/blem-psa-16-m4-5-56-nato-1-7-nitride-triangle-classic-upper-with-bcg-ch-and-carry-handle-black.html
Also thanks for having me glad to be on the forum