Single loading the AR-15 for slow fire strings presents the same opportunity for failures to feed—jamming—as does shooting rapid fire. Replacing the standard magazine’s follower with a single round follower can help prevent such stoppages, and another solution is the “sled.” A second advantage to both sled and single round follower is that we can handload cartridges to a longer overall length for best precision, not restricted to magazine length.
Single loading a standard, unmodified magazine during a slow fire string requires dropping the cartridge in the ejection port then pushing it downward to seat into the mag below the feed lips. The AR-15’s comparatively small ejection port can make this difficult for some, especially those with large hands, and failure to do this properly results in the cartridge jamming in the action on bolt closure. While mostly an annoyance when slow firing offhand, when shooting prone slow fire at 600 yards, the shooter then must break position to clear the jam and, with only 20 minutes for 20 shots for record—and maybe your target puller isn’t the liveliest you’ve ever seen and is eating into your time—it can be a real problem. Plus, the jammed cartridge is now damaged and may result in a flyer, so it must be discarded.
Single Round Follower
When scoring for other competitors, we still sometimes see them single-loading standard magazines, but most have installed a single round follower in a spare magazine or gone to a “sled.” The single round follower replaces the standard magazine follower and is configured to align the cartridge with the rifle’s chamber so that pushing the cartridge down into the magazine is not necessary—just drop the cartridge on top of the single-round follower and press the bolt release.
I have used these, but sometimes the bolt failed to lock back after firing, requiring breaking position to cycle the charging handle. Also, a dropped-in cartridge would sometimes ride atop the follower’s left side, against the upper receiver left wall, then jam the bullet nose against the receiver extension upon pressing the bolt release.
Sledding
A sled is a false magazine configured to fit the rifle and permit only single loading. Sleds for the AR-15, M-14/M1A, M1 Garand and others are available, and I found online a 3D-printed sled for the Ruger 10/22 and other rifles that accept the 10/22 magazine. Sleds are typically made of some kind of synthetic that has less friction than aluminum followers, offering slicker feeding, and a wide, rounded trough formed into the top holds the cartridge in alignment with the chamber.
Topping the “Best of the Best” list for the AR-15, the Original Bob Sled is a hefty chunk of CNC-machined Delrin that slips easily into the mag well and locks firmly into place. Three features make the Original Bob Sled superior to others. First, the trough where the cartridge lays is significantly wider and deeper than that on the AR-15 single round followers I’ve seen, so the sled is less fussy about how the cartridge is dropped in. Secondly, the faux feed lip on the left side is chamfered to preclude the above-mentioned jamming; if a dropped-in cartridge lands atop the faux feed lip, it rolls off, into the trough. Third, a plunger assembly at the rear of the Bob Sled positively engages the AR-15’s bolt catch lever to hold the bolt open after firing, and being rounded and spring loaded, easily permits the bolt to move forward to close when the bolt release is pressed.
Easy Fix
I bought my Original Bob Sled maybe 20 years ago and can’t even begin to estimate how many thousands of rounds it has fed through my ARs for competition and load development. Some time back, it began failing to hold the bolt open after firing a shot. A close examination showed the bolt hold-open plunger assembly to be threaded for height adjustment, but it obviously requires a dedicated, split-bladed or prong-type tool to turn the plunger assembly. An email exchange with the manufacturer, Bob Hahin, had an appropriate adjustment tool and spare plunger assembly on the way to me for just a couple of bucks, and the Original Bob Sled is sledding again like new.
Original Bob Sleds are also available for the AR-10, FN-FAL and in the AICS configuration. The “6mm-15” model for the AR-15 works for cartridges with cases of diameter larger than that of the .223 Remington/5.56 mm NATO, such as 6.5 Grendel, 6.8 SPC and similar. You can purchase an Original Bob Sled directly from the maker, as well as from many of the well-known suppliers of competition shooting sports gear, such as Creedmoor Sports ($44.95 for an Original Bob Sled configured as an AR-15 20-round magazine).
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