The Beretta Px4 Storm Special Duty is a semi-automatic pistol chambered in .45 ACP, built on a polymer frame with a Flat Dark Earth (FDE) finish. It uses Beretta's DA/SA (double-action/single-action) system with a rotating barrel. 
 

Key Specifications 

• Brand: Beretta 
• Model: Px4 Storm Special Duty 
• Caliber: .45 ACP 
• Action: Single/Double Action (DASA) 
• Capacity: 10+1 rounds 
• Barrel Length: 4.5 inches 
• Weight: 1.8 lbs (28.60 oz) 
• Finish: Flat Dark Earth (FDE) 
• Grip Type: Interchangeable backstrap with FDE finish 
• Sights: 3-Dot White 
   

Detailed Features 

The rotating barrel system reduces recoil by converting some of the rearward bolt thrust into rotational energy. Interchangeable backstraps let shooters adjust grip circumference for fit. The ambidextrous firing pin safety blocks the firing pin unless the trigger is pulled. Three-dot white sights work across a range of lighting conditions. 
 
At 1.8 lbs. the frame is lighter than comparable all-metal pistols in .45 ACP. The 4.5-inch barrel is full-size service length.

The Px4 Storm Special Duty in FDE .45 ACP draws mixed but generally positive feedback. The ergonomics and comfortable grip are frequently mentioned as positives -- the interchangeable backstraps help it fit different hand sizes. Reliability and accuracy at range get good marks, and the .45 ACP caliber is a preference for shooters who prioritize larger projectile diameter.

The rotating barrel and reduced felt recoil get positive mentions, though some users note the DA/SA trigger is heavier in double-action than they prefer. The size is the main practical concern -- the Px4 Storm is a full-size pistol and is bulkier than compact carry options, which makes IWB concealed carry more challenging.

The FDE finish gets positive aesthetic feedback. Overall the gun is viewed as a capable service pistol; the target buyer is someone who wants a full-size .45 ACP for home defense or range use rather than a slim carry piece.