While popping rounds into the magazine of my first 6.5 Grendel rifle, I looked at those cases and contemplated necking them to .224 caliber and adding a fast barrel twist to handle heavy-for-caliber bullets. Gun-savvy friends reminded me this would simply create a 22 PPC – though that round used a much slower rifling twist. I wasn’t the only one to ponder this idea, as the 224 Grendel was eventually thought of by inquisitive gunsmiths like Jack Allman of Upriver

Precision Arms in Santa, Idaho. Allman started work on the 224 Grendel years ago, building rifles with fast 1:7-twist barrels to handle long, high-ballistic coefficient (BC) bullets for long-range shooting. Justin Stout, who introduced me to Allman and the 224 Grendel, began successfully using both the wildcat cartridge and Allman’s custom rifles in Precision Rifle Series competitions.

Allman created the 224 Grendel by necking 6.5 Grendel brass to .224 caliber via a series of bushing dies, with no other dimensional changes applied, maintaining the round’s 30-degree shoulder and leaving neck length as it emerged from sizing – about .26 inch. This created a case with an approximate 10 percent improvement in powder capacity over the 22 PPC. All this work started well before Hornady introduced the 22 ARC in 2023. The announcement of the new round elicited some small amount of anxiety, but ultimately Hornady submitted the exact chamber dimensions for the Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI) approval as Allman had used (Hornady’s free-bore specifications slightly shorter). So, the 22 ARC it is.

Allman’s initial loadings revolved around minimizing wind drift at long ranges for steel-plate shooting, followed shortly with experimentation with lighter varmint bullets, and finally, options for feral hogs. Allman hunts hogs with family in California, while Stout has accompanied me to Texas, where these experiments act as proving grounds for the 22 ARC as a big-game round. This isn’t a stretch, the 22 ARC convincingly outpaced the 224 Valkyrie that was touted as big-game ready upon its introduction. This is contingent on the right bullets, of course.

I’ve taken hogs up to 300 pounds using the 22 ARC loaded with bullets like Hornady’s 88-grain ELD Match and 90-grain A-Tip Match sent at around 2,900 feet per second (fps). These bullets certainly weren’t ideal, particularly at ranges inside 200 yards as they tended to open too aggressively after encountering bone – even ribs – creating large entry wounds and essentially shotgunning vitals without exiting. Those hogs died quickly, but there was worry of eventual failure.

Controlled-expansion bullets posed an obvious solution – monolithic copper or bonded lead-core numbers that have become more widely available and typically requiring every bit of the fast rifling twist that is a 22 ARC standard.

The test vehicle for this series was a parts-build AR-15 fitted with a somewhat heavy 22-inch Shaw Custom barrel with a 1:7 twist. This started with a redundant 224 Valkyrie AR-15, believing I could get into a 22 ARC cheaply and quickly – neither of which occurred. The bolt carrier and magazine required appropriate replacements (Aero Precision’s 6.5 Grendel bolt in this case). The initial shooting resulted in excessive smoke/fouling (especially with a suppressor installed) and occasional jams, though accuracy with Hornady factory ammunition proved satisfactory. I ordered a heavier H3 buffer, new buffer spring and tube to encourage slightly longer bolt lock-up time, all of which were, of course, backordered. After the parts arrived, the rifle’s adjustable trigger began discharging when pulled and released, producing annoying double discharges. It was replaced with a 3-pound Velocity Precision Engineering MPC Trigger. A FAB Defense R.A.P.S. fully-adjustable buttstock was added and all my tribulations came to an end. Or so I thought…

As varmints will remain a primary target with this rifle (hog hunting will involve a thermal-imaging unit), I mounted a Huskemaw Blue Diamond 5-20x 50mm long-range scope in Precision Hardcore Gear four-hole 30mm Force Recon Tactical rings. These rings included an integral bubble level and high configuration suitable to AR geometry. This is a second focal plane (SFP) scope designed to simplify long-range shooting, including an exposed 1/3-MOA elevation turret and HuntSmart Reticle for quick wind corrections.