Why it matters: Belt-fed uppers for standard AR-15 lowers became a practical civilian category once forced reset triggers were cleared at the federal level, and price has been the main barrier. Lima Six sells one for about $3,000, and this review is a detailed account of what that price means in use.
The YouTube channel Brass Facts has published a long-form review of the Lima Six belt-fed upper, an AR-15 upper receiver that feeds 5.56 ammunition from linked belts. The host, who calls himself a belt-fed enthusiast, says he bought the short-barreled variant with his own money. He ran it through drills, shot it to 500 yards, used it in a forced reset trigger match and finished with a 500-round burndown. The question he sets for himself is whether the compromises needed to reach the price leave a usable civilian belt-fed or, in his words, "more of a toy."
Lima Six lists complete 12.5-inch and 18-inch uppers at $2,999.99 and build kits from $1,999.99. The host's point of comparison is the FightLite MCR, the established belt-fed upper for AR-15 lowers, which he puts at about $8,000 and describes as "pretty finicky." He credits forced reset triggers with letting civilian belt-feds run "more or less as beltfeds were intended" after years as semi-automatic curiosities.
Lima Six belt-fed design: direct impingement and a stretched receiver
Most belt-feds use a gas piston with a regulator. The Lima Six uses direct impingement with a RifleSpeed adjustable gas block. The host calls this a compromise: the block is hard to adjust on a hot gun and will carbon-lock over time. He also says it tunes more usefully than the MCR, which he says runs reliably on only one of its three settings. On the gas tube, a known failure point in sustained fire, he argues that Lima Six's straight, reinforced tube would only rupture after something like 1,000 rounds of continuous fire, a point where other parts are also failing. He reports his Lima Six held its lubricant through about 1,000 rounds over several months, while his suppressed MCR tends to dry out in a single range trip.
The feature he was most interested in is the stretched receiver. He says it gives the bolt carrier about three-quarters of an inch more rearward travel than legacy designs, which he puts at about half an inch; Lima Six advertises 23 percent more carrier travel. In his account, the extra run-up lets the carrier strip rounds from M27 links without the heavy buffers, stiff springs and extra gas he says MCR owners often use.
He praises the feed lid's fit, reporting no rotational play, and says the gun held zero for the entire review at roughly 3 to 4 MOA. He also credits the bolt carrier's full-size cam, enhanced firing pin and dual ejectors, noting that his MCR's firing pin broke at 4,000 rounds.
Feed tray, charging handle and reload problems on the Lima Six
Most of his criticism is about handling. The feed tray is pinned in place rather than pivoting. He says that blocks access to the area in front of the chamber during complex malfunctions and traps loose cases and links underneath. He says the tray's raised edges are sharp enough to cut bare hands and wear through gloves. The charging handle is fixed to the bolt carrier, so it reciprocates and gets hot, and he says it has cut him too.
His main objection is the feed arm, the part that turns bolt movement into belt feed. On many belt-feds it collapses; on the Lima Six it is fixed, so the lid cannot close with the bolt forward. Combined with no last-round hold-open, that means every reload starts with locking the bolt to the rear. He calls reloading from an unsupported position "an absolute nightmare" and estimates a collapsing arm would add $150 to $200 to the price, which he calls "a no-brainer." He does not fault the lack of a quick-change barrel, saying it makes sense at this price.
Lima Six reliability record and burndown test results
“The host's heaviest criticism is not reliability but the reload: with no hold-open and a fixed feed arm, every belt change starts by locking the bolt to the rear.”
J.D. Whitfield, The ReticleThe first unit he received was a prototype with a fixed gas block. He says its reliability dropped to about one malfunction in 25 rounds whenever conditions were less than ideal, and it was replaced with the adjustable-gas-block version. He acknowledges viewers may suspect the replacement was hand-picked, and says he reviewed it on the assumption that it represents production guns.
The second unit logged about 3,800 rounds. There was one malfunction in its first 1,000 rounds. After about 1,300 more, rain stripped its lubricant and caused surface rust, followed by a couple of major malfunctions back to back. It had four malfunctions in the next 1,000 rounds without cleaning or lubrication, then none in the 500-round burndown. He says two other owners report similar results: reliable when lubricated, less so when dry. His summary is that the MCR is somewhat more reliable run dry, the maintained Lima Six is more reliable overall, and the MCR is easier to clear.
The burndown used his short-barreled, suppressed configuration, which he calls close to the worst case for heat. It was 100 rounds of continuous fire, then 400 rounds in three- to five-round bursts with pauses, averaging 107 rounds per minute over about six minutes. The first cookoff came about 20 seconds into a pause after roughly 300 rounds, with two by 400 and repeated cookoffs at intervals of about five seconds by 500. He recorded pierced primers, which he blames on the gun's heat, but no popped primers. Every round hit paper at 110 yards; groups opened to 6 or 7 MOA hot and returned to 3 to 4 MOA cold, with zero unchanged. His conclusion is that the gun is useful at an elevated rate of fire up to about 300 rounds, and a "major liability" beyond that. He now locks the bolt open during pauses to prevent cookoffs.
The review also covers the Hydra lower from Hydra Weaponry, which the host says was provided free. He says it moves the belt adapter closer to the centerline but gives up dual feed. The video's sponsor is Venture Surplus. The host says he spent more than $6,000 on the video and does not take payment for reviews. His verdict is that the Lima Six "does a good job of being sort of the everyman's" belt-fed, provided owners accept its maintenance needs and change how they use it to match its heat limits.
For context
- In May 2025 the Justice Department settled its litigation with Rare Breed Triggers, ending federal efforts to treat forced reset triggers as machine guns; a number of states still restrict them.
- The FightLite MCR is a piston-driven belt-fed upper that fits standard AR-15 lowers and can feed from belts or magazines, and it is the best-known civilian belt-fed upper.
- Civilian semi-automatic belt-feds fire from a closed bolt, leaving a round in a hot chamber between strings, which is what makes cookoffs possible; military light machine guns such as the M249 fire from an open bolt.
- M27 links are the standard disintegrating links used to belt 5.56 NATO ammunition.
