The Rock Island Armory Ultra FS is a .45 ACP semi-automatic pistol built on a steel 1911 frame with a parkerized finish. It ships with G10 grips and an adjustable rear sight. 
 

Key Specifications 

• Brand: Rock Island Armory 
• Model: Ultra FS 
• Caliber: .45 ACP 
• Capacity: 8 rounds 
• Barrel Length: 5 inches / 127 mm 
• Overall Length: 8.75 inches / 222 mm 
• Width: 1.3125 inches / 33 mm 
• Height: 5.5 inches / 140 mm 
• Weight: 2.49 lbs / approximately 40 oz 
• Action Type: Semi-Automatic 
• Frame Material/Finish: Steel, Parkerized 
• Sights: Dovetail Fiber Optic Front, LPA MPS1-Type Adjustable Rear 
• Trigger Pull Weight: 4-6 lbs 
   

Detailed Features 

The five-inch button-rifled barrel with six grooves gives consistent performance at range distances. The parkerized steel frame resists corrosion without looking flashy. G10 grips keep the gun from shifting under recoil and hold up in wet conditions. The fiber optic front sight picks up light quickly, and the LPA MPS1-type adjustable rear lets you dial in your zero. 
 
At 2.49 lbs this is a full-size, all-steel pistol. It is heavier than polymer-frame guns, which keeps muzzle flip moderate with .45 ACP. 
 

Usage 

The Ultra FS fits well in IPSC or IDPA classes where the 1911 platform is allowed, and the adjustable sights help dial in competition zeros. For home defense the .45 ACP caliber and single-action trigger provide a straightforward manual of arms. At the range the manageable recoil and comfortable grip make longer sessions practical.

Most owners of the Rock Island Ultra FS in .45 ACP come away satisfied, though a few recurring critiques are worth noting.

On the positive side, build quality gets consistent praise. The parkerized finish holds up to regular use, and the pistol feels solid in hand. Trigger feel is a frequent high point — owners describe it as smooth and with a clean break, which helps with accurate shots. The weight, while substantial for a carry gun, is seen as an asset at the range since it absorbs recoil well.

On the negative side, some owners mention a break-in period during the first few hundred rounds where feeding isn't fully reliable. Magazine compatibility can also be an issue — certain aftermarket magazines work better than others. A handful of users point out that the feature set is basic compared to modern striker-fired pistols, which is expected for a traditional 1911 at this price point.

Overall the consensus is that it punches above its price for a steel-frame .45 ACP 1911 and is a reasonable first 1911 purchase.