Low-profile is a term with several meanings.
Low Profile usually refers to the height of the receiver on an over and under shotgun. There is wide variation in receiver height among today's over and unders. The current Citori and the original Superposed (designed by John Moses Browning) each have a mid-range profile height as measured from the top point of the receiver the to bottom of the receiver.
In some cases it refers to the profile of an open sight system on a rifle. See the description at bottom of this page for more detail.
Low Profile Receiver.
The Citori 725 and the Browning Cynergy have lower profiles than the average height. The Cynergy, with it's special receiver design is the lowest profile receiver ever offered by Browning and possibly the lowest in history. The Citori 725 also has a significantly reduced receiver height.
Take the Citori 725 for example. There are several advantages to a low profile receiver that can be explained using the Citori 725 as the example. The new Citori 725 is the evolution of John M. Browning’s legendary B25 Superposed, now with the modern performance advantage of a low-profile receiver. The new 725 receiver is significantly lower than other Citori 12 gauge receivers, yet the 725 shares the renowned durability of generations of Citori over and unders with the rugged full-width hinge pin and tapered locking bolt design. So what happens when a receiver is lower? Lowering the receiver is done by positioning the barrels lower in the receiver which effectively moves your forward hand closer to the bottom barrel and also to the top bore centerline. This changes the relationship of your cheek and eye to the rib itself putting face, eyes and hands more in line (closer) to the centerline of the gun. This "in-line feeling" presents an uncanny sensation of fit and natural feel when you shoulder a 725. You might think this is merely subjective, but it is a primary comment when shooters try out a low profile gun like the 725 for the first time.
Improved recoil control and less muzzle jump are also two of the big benefits of a low-profile receiver. There is also the "one with the gun" feeling that makes the shotgun act like an extension of your body. The image below -- showing the reduction in height -- details a Citori 725.
Low Profile Sights. Low profile can also refer to the height of a rear sight such as found on many BLR rifles. The advantage of a low profile sight in this instance is that it reduces the possibiity of the sight snagging as it is pulled in and out of a scabbard or case. A lower rear sight also allows the front sight to equally low on the barrel. BLR rifles are often used hunting from horses, and the ability to flawlessly remove the rifle from the scabbard is an important part of successful hunting from a horse. For that reason, a low profile sight (front and rear) is preferable.
The rear sight shown below is from a BLR Takedown.
The Tech-Term "Low-Profile" is referred to in the following products: