The Leupold Tactical Prismatic Scope comes with an integrated mounting system, making it readily mountable on standard Picatinny rails. The mount comes with spacers to adjust the height above the receiver. It took only a few minutes to clamp our scope on the integrated Picatinny rail of the Kel-Tec. Leupold's included mounting screw was designed to accept a ratchet on the inside of the screw head and socket on the outside.
After mounting, one focuses the eyepiece so a well-defined reticle floats in the field of view, then fixes the focus in place with a locking ring. We adjusted it once and this adjustment worked for a wide variety of testers.
Our optic did not have any internal glare or reflections, regardless of the light source or ambient light. It was superimposed on the target with both eyes open. The shooter enjoyed a seamless, glare-free field of view.
Leupold uses a DiamondCoat2 scratch-resistant coating, designed to increase light transmission and abrasion resistance. When we first mounted the Leupold we tested the coating. We were getting ready to mount it during a test, when we … er … um … dropped it. Okay, perhaps this was an impromptu test but the optic did land directly, yes directly, on the corner of a rock. This was a "one-in-a-million" type of accident — not because optics testers lack butterfingers but because Leupold really recesses its lenses inside the metal case. Our ocular lens hit the corner of a rock on the center of the optic from several feet off the ground.
The rock mishap was separate from the other abuse users routinely give optics products. It did, however, prove one thing: The DiamondCoat2 scratch resistance works (and boy, are we glad). The Leupold Tactical Prismatic Riflescope was subjected to a number of other abuses, but none as harsh as smacking it on a rock.
Kel-Tec designed the SU-16 from the ground. Some of the features — like a reversible safety button — are a dramatic improvement in combat carbines. Kel-Tec has capitalized on some of the advantages of the front piston semi-auto design. For example, they make a pistol version (the Kel-Tec PLR). AR-15 pistol "clones" need a buffer tube in order to function, which sticks out of the back of a pistol version. Many manufacturers try to camouflage the buffer tube, which looks like an unsightly horizontal broomstick jutting out the back end. Kel-Tec's design separates it from this grouping, and as a result the pistol looks and works better.
The SU-16 was subjected to a significant amount of abuse, including allowing dirt and sand in the receiver and firing magazine after magazine. The synthetic receiver was designed to be forgiving, adding to its reliability and almost nonexistent recoil.
The Kel-Tec worked in dusty conditions when primed with a dry lubricant. We used the Smith & Wesson Dry Lube with Cerflon (distributed by Brownells). It was suitable for dry areas but we switched to Smith & Wesson Advanced Gun Oil when it wasn't dusty.
The SU-16 was not designed for precision matches, but it has acceptable accuracy at carbine ranges. It uses a simple trigger mechanism which was designed for safety and utility, not shooting matches. At 50 yards, it routinely produced 5-shot groups that could be covered by a quarter. Out to the 100-yard mark, it will center mass a torso-shaped target every time, which is all that should be asked of carbines. Most importantly, at high-risk car-stop distances, it was a precision instrument. With the Leupold Tactical Prismatic Riflescope, officers prevailed in multiple target scenarios.
However, the testing team generated some minor design suggestions for the SU-16. First, the team liked the way the firearm folds in half but wished it could pivot so that the entire trigger guard fits inside the magazine better to aid in protection. Second, the assembly pin, which is removed to pivot the rifle, should protrude a little with a ring so the user can grab it, rather than poke it through. The team suggests attaching this pin to the rifle, such as with a lanyard. The pin is one of those things that an officer should have extra in the pocket. The design suggestions have little to do with the unit's performance, of which there are no complaints.
For some reason the SU-16 is much louder than other carbines with similar features. Everyone noticed. It could be that impinged gas systems like the AR-15 carbines are just inherently quieter.