A pistol buffer tube and SB Tactical SBX-K pistol brace are what comes with the FN 15 Pistol, but we took the opportunity to test the awesome new SB Tactical 4-position-adjustable SBA3 brace/buffer tube kit here. Controls are Mil-Spec and a Magpul MOE grip is standard. Although a Lancer magazine is shown, the pistol actually comes supplied with one 30-round Magpul PMAG instead.

Most of the subsonic ammunition functioned without issue, the only exception being some 240-grain SMK from Doubletap Ammunition and 220-grain RUAG. To be fair neither runs consistently unless the gun is over gassed. It had no issues with the Lehigh Defense 194-grain or the new Hornady 190-grain Sub-X. Sig Sauer’s 220 was clean, reliable and soft shooting, with consistent ejection—a great practice round. 

Barnes 90-grain Range AR was very reliable and clean shooting without some of the recoil you get with full-boat loads, another perfect practice round. Black Hills 125-grain TMK was the harshest, but it’s loaded about as hot as you can load a 125-grain 300 BLK. Everything supersonic ran well, including the 110-grain Barnes TAC-XP, an excellent self-defense load.  

50-yard performance with supersonic loads was stellar across the board, best tightest with SIG’s 125-grain Elite Match, producing this 0.75-inch group

SureFire’s Pro Comp has been around a long time, and this is the second rifle I’ve tested with one in a month. Originally designed with working professionals in mind, it has very little blast directed toward the sides and shooter. As brakes go, it’s one of the most comfortable shooting. It sends downward pressure evenly for those using bouncy bi-pods lending to consistent accuracy. Recoil reduction is noticeable—not as good as dedicated brakes, but it does not shake your teeth loose when you shoot it, or drive debris into the next zip code. Fired next to snow on a vehicle it moved the snow, but not like some others. Shooting off snow-covered barricades, car hoods and obstacles, it never distracted me from the target. Make no mistake, it’s loud, just like any other brake, but not to you, and with barrels this short that’s critical. Flash suppression with clean ammunition was excellent. The best part about this brake is the retail price ($59), a great buy these days and it may be the least expensive thing SureFire makes!

Testing subsonic loads, the SIG brand snuck out a win again, producing this 0.70-inch 5-shot group with the 220-gr. OTM offering.

The pistol’s barrel length (12 inches) is about perfect for usable ballistics, a tad longer than most AR pistols in 300 BLK. It takes a bit more effort working in and out of the car or in tight spaces but it functions with most ammunition. While 300 BLK works better than most calibers out of a 6-inch barrel, it does not cross over well from supersonic to subsonic. Using the 12-inch barrel makes it reliable and clean running with both.  Loading up a single 30-round magazine with a mix of everything tested, it did not miss a beat. You give up a bit of convenience and concealment but gain reliability. More importantly, you get as much effectiveness as possible with this caliber using hunting and self-defense ammunition. Most subsonic ammunition is over penetrative and under expansive in general, worse from shorter barrels. Same problem with supersonic in a typical 6- to 9-inch barrel. With the 12-inch barrel you get optimal expansion for design on both sides.

SB Tactical is the innovator for the pistol brace and their devices are excellent. One of the downsides of pistol braces has been the inability to adjust for length. Partially restricted by the initial ATF decisions, subsequent rulings make it lawful. If you have short, thick or odd-sized forearms, its really tough to get a solid hold with a fixed brace.   Their latest, the SBA3, adds the ability for some length adjustment as well as a QD attachment for a sling. It lets you move that brace to the best spot on your forearm for a solid, single-handed hold. It also eliminates the drop at the rear from the original, letting you line things up straighter.

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