The Brownells’ version of the XM177E2 is a near-faithful reproduction of the Colt carbine of the 1960-1970s era. One thing you notice immediately upon handling is just how lightweight this period-correct carbine is. This is interesting given that today many are attempting to lighten the AR platform by using alloys, polymer, pencil diameter barrels and furniture resembling cheese graters. Improved 21st century technology aside, it seems to me our fathers may have been on to something. The XMBR177E2 weighs in at 5 pounds, 13 ounces, or over a full pound less than its already lightweight M16A1 brother.

A 12.7-inch barrel sits in place of the original XM177E2 11.5-inch, and features a pinned and welded, correct-looking moderator muzzle device to appease barrel length restrictions. This rifle is built with all new parts, not having to rely on surplus-part channels to complete a rifle.

The pencil diameter barrel is 12.7 inches long with a bayonet lug and permanently attached muzzle device that brings the barrel to BATFE legal length. The muzzle device is for aesthetics only, as it has no internal baffles like the original. OAL is a compact 34 inches. The XMBR177E2 retains the two-piece, interchangeable handguards, the tiny CAR-15 two-position stock, and fixed carry handle on the upper receiver. However, the receiver extension is the contemporary 6-position versus the original open-closed 2-position. The A1 version pistol grip is smooth, with the rarely used sling swivel protrusion on the bottom front. The sights are the A1 type, with both the front and rear sights being five-position, adjustable via the tip of a typical carbine round. The forged aluminum receivers are finished in a black matte, with the lower bearing a Brownell’s stamp. Controls are in the usual positions, with a teardrop forward assist and mil-spec single-stage trigger, which broke for me at a better than expected 4.75 pounds. The safety is marked only safe and semi-auto. The XMBR177E2 comes in a padded cardboard “Retro” marked box, with the period-correct, cartoon-style M16A1 service manual, and a standard capacity 20-round aluminum magazine.  

At 50-yards, using only the rifle’s iron sights, the Brownell’s turned in a very respectable 1.25-inch five-shot group with Federal 55-gr. XM193

Firing the XMBR177E2 demonstrated few surprises. The original XM177 had a 1:12” barrel twist, making it suitable for the standard 5.56×45 NATO, 55-grain XM193 ball ammo of the time. Anything much heavier than that would likely require a more aggressive barrel twist to have reasonable accuracy, namely 1:7” to 1:9” as current AR15/M16 variants have. I therefore chose two different military rounds, Federal 55-gr. XM193, and the current 62-gr. Federal M855 green-tip ball, with some civilian MFS 55-gr. ball for testing. As I was using only iron sights and 50-year old eyes, my accuracy tests were conducted at just 50 yards from a bench. In any case, the Brownells’ XMBR177E2 shot well, with the best five-shot group being turned in by the Federal 55-gr. XM193 at a hair over an inch and slightly right. Averages for both 55-gr. loads were in the 2- to 2.5-inch range. As anticipated, the 1:12” twist barrel did not like the heavier 62-gr. at all, throwing 5+ inch groups about eight inches right of POA, with many keyholes indicating loss of stability.

Extending to 100 yards just to check it out, groups opened up to around five inches with XM193, but still within the acceptable, minute -of-man area. Ejection was consistently at 1 to 2 o’clock with all loads, demonstrating some over-gassing unmitigated by the standard weight buffer. Reliability was flawless throughout, utilizing the issue 20-round aluminum mag, as well as other 30-rounders from Troy, Magpul, Lancer and aluminum mags. Overall, I enjoyed shooting the Brownells’ Retro XMBR177E2, and would recommend it both to collectors or anyone wanting a very lightweight, vanilla AR-style rifle for defensive purposes. You can order your XM177E2 ($1,049.99 to $1299.99) directly through Brownells for delivery to your dealer at: Tel.: (800) 741-0015; Web: