In the case of this particular rifle, switching to a free-float fore-end resulted in an accuracy improvement of 50 percent. This half-inch group was fired with 75-grain Hornady TAP.

I opted for the U.S. Army’s current issue Aimpoint M68 CCO (Close Combat Optic)/M68 3X Magnifier combination ( www.aimpoint.com ). The M68 system comes with a quick-release mount that allows the magnifier to be removed, literally, with the twist of a wrist, which makes this a perfect sighting system for situations where both close combat and long-range shots may be required.

I also like the Aimpoint system because it is simple to use. You just place the dot where you want to shoot and press the trigger.

For targets, I used three-inch Shoot-N-C dots from Birchwood Casey as they would offer a nice contrasting background for the red dot of the Aimpoint.

I selected Hornady 75-grain TAP boattail hollowpoint (www.hornady.com ). This new 5.56 load is designated the T2 because it was designed especially for enhanced performance in carbines.

Used extensively by Special Forces Units in Iraq and Afghanistan, the T2 load differs from other loads in that it takes into account the direct gas action system of the AR-15 and its sensitivity to ammunition.

The T2 bullet has a unique ogive shape designed to facilitate feeding in M4 weapons systems. A cannelure was added to the bullet to facilitate case-mouth crimping and resulted in bullet push/pull forces that meet or exceed mil-spec standards. Hornady also uses a mil-spec primer (due to the free-floating firing pin) and crimped it in the case to preclude primer back-out and thereby limit unintended discharge.

The standard 75-grain Hornady TAP load has proven to produce one-minute accuracy out of 20-inch AR rifles, so I had little doubt that it would prove to be quite accurate in the short-barreled Model 3.

I benchrested the Model 3 on my Blackhawk Battle Bag and shot a series of five-shot groups. The temperature was 77 degrees with a negligible breeze that was coming from the rear. My best group measured 11⁄4 inches, my worst, 21⁄4.

I then sent the gun off to Mark at Stag Arms and waited for its return, which didn’t take long. Stag installed the new gas block and fore-end in a day, and I was back at the range later that week to resume testing.

The first thing that I noted about the Model 3 as I took it from the shipping box was that it was noticeably heavier. This was due to the aluminum versus the plastic fore-end, which is also twice as long as the standard two-piece plastic unit. I also noticed that the trim profile of the JP/V-TAC fore-end was more pleasing to my hand.