I have just been bitten by the retro bug, and want to put together an XM177E2 clone. Problem is, I'm not really clear on what parts I need to acquire to do so. I'm not concerned with the rifle being all original/all Colt. I would also like to avoid the 1/12 barrel twist if I can. Thank you all in advance for any help you can provide.

You may need to wait until parts are back in stock around the world but depending on how original vs repro you want it to be will determine a lot.

You could start with a carbine gas system M4 barrel of any twist and have it reprofiled to pencil or you could buy someone's "barrel kit" like Model1 Sales or Retro Rifle offers. Lots of options, not all authentic.

Look at Brownell's "retro" line in the meanwhile.

"Retro Rifles"......research that one before spending your money there.

Thanks for the replies and the guidance! I'm sure I can build the lower as I have built several. The barrel and gas tube are going to be a new thing. I would really like to get my hands on a 1/7 or 1/9 "pencil" barrel and have the fake moderator pinned and welded. Once I get that done I think I can take it from there. Saw mixed reviews concerning Retro Rifles. I'll probably pass.

https://www.brownells.com/rifle-parts/barrel-parts/rifle-barrels/ar-15-12-7-a1-carbine-barrel-assembly-prod97901.aspx?avs%7cManufacturer_1=BROWNELLS%2bMILITARY%2bBARRELS

If you get someone like John Thomas to pin on a reproduction XM moderator, it comes out to just a bit over 16. They are out of the 1x7's at the moment. I went a similar way to what you are thinking of, retro except for the barrel twist so that I can run heavier stuff if that's what I feel like doing. Probably my favorite AR. A year after I finished it I still pick it up and think 'hell yes'.

This is exactly what I used on mine  - 1/7 and all. I had ADCO do my pin/weld job, but I wouldn't hesitate to recommend John either - he did my Proto furniture work and it's incredible.

Note that the assembly Brownells has isn't quite right for an E2 - they had a delta ring and not a slip ring - but that's an easy and cheap fix.

AR15sport.com sells XM gray delta rings

If you want a vinyl acetate car15 stock that is cheap essential arms makes a really nice copy. Make sure you order the castle nut and buffer tube at the same time though for proper fitting.

Do you mean the coated Aluminum stock?

I used a NOS Bushmaster 1-9 LW barrel I had laying around.

What barrel configuration should I be looking for? .625 16" carbine? Anything from 1:7 to 1:9 twist is fine with me.

Whats up with the new barrel they have. Says it's 12.7in, 1-12 twist, "rifle gas system"? How's there a rifle gas tube on a 12.7in barrel?

Typo, probably

If you want to buy a build-ready barrel, Brownell's and Model1 Sales have XM177 setups ready to roll. 1-12 is correct and average but 1-7 is an option albeit out of stock at Brownell's. I don't like M1S's moderators, Brownell's repro moderator is accurate.

If you want to build from scratch, there are a few pencil options out there, stock is scarce right now.
Ballistic Advantage has a 1-7 carbine gas 16" pencil barrel that you can have cut down to 11.7"

The other way is to buy an 16" M4 carbine gas barrel in your desires twist and have it reprofiled and cut down.

Sample of one, but I ordered a repro fiberlight for my clone before I had read the bad reviews.  Shipped the next day. Debating on rilling the dice again to order some more parts.

OP- brownells has a great deal on 1/12 chrome lined 11.5 barrel assembly with flat delta assembly etc.  I fear they may stop selling some of these so I would jump fast on the barrel if you are interested and will be happy with the original 1/12.

I have a 1/7 pencil barrel And flash hider/grenade ring from Brownells on a CH code upper with the original charging handle. Let me know if you want it. Barrel is new and currently has the A1 birdcage on it. Shot 2 rounds to test.

Spikes,Doublestar makes 1-7 11.5 pencils I think

IMO, the first thing you have to consider, with any retro, is how "original" do you want to go.  Sounds like you're there, you don't need to track down all Colt parts.

The second thing, specific to an XM177E2, is how "authentic looking" do you want to go.  An E2 had an 11.5" barrel with a moderator; this did not add up to the 16" of barrel length that the ATF requires for a civilian rifle.  So, if you want the authentic E2 look, you are in SBR territory.  Your other option is to go with a longer barrel (approximately 12.7" assuming a 5.5" faux moderator) and have them pinned and welded to make the ATF happy, but you'll have people telling you the barrel is too long and it doesn't "look right."

(EDIT: forgot to add the pistol option as opposed to SBR.  The problem with this route is that there really isn't a "factory" pistol brace that looks good on a retro.  A member here is 3D printing one, but his availability is limited.)

At the end, my advice is always, "you do you."  If you don't want to (or can't for some reason) mess with an SBR, then build it 16".

For the record, I went the non-SBR route; at the time I was planning my upper, my state did not allow SBR's, and by the time that was changed, I already had the barrel, so I wasn't gonna change.



Brownell's slickside upper, Brownell's 12.7" barrel, Brownell's faux moderator.  Pin & weld by JT at Retro Arms Works.  The barrel is a 1:12, if I remember right; this was the first run of these barrels they did, where they goofed up and put a triangular handguard cap on.  I bought one as a "blem," since I wanted a 607-style carbine-length triangle handguard anyway.  So mine looks even less "right."  

Hey, if anyone has a lead on an A1 lower please let me know. Stripped or not, doesn't matter. Thanks!

Abandon hope all ye who enter here.

Run!

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If you go with a 16" pencil barrel, you can use a slipover-style XM flash hider. Gives you the look of  a short barrel w/o the ballistic loss.