Question: The TT-30 pistol was developed in the early 1930's as a replacement to a revolver designed by who?

Context paragraphs:
Smith &amp; Wesson Model 13: The Smith & Wesson Model 13 (Military & Police Magnum) is a .357 Magnum revolver designed for military and police use.  It is based on Smith & Wesson's K-frame—specifically, it is a .357 Magnum version of the heavy-barrel variant of the .38 Special Model 10 (originally called the Military & Police).

Protector Palm Pistol: The Protector Palm Pistol is a small .32 rimfire revolver designed to be concealed in the palm of the hand.  It was unique in that the revolver was clasped in a fist with the barrel protruding between two fingers and the entire handgun was squeezed in order to fire a round.

Colt Dragoon Revolver: The Colt Model 1848 Percussion Army Revolver is a .44 caliber revolver designed by Samuel Colt for the U.S. Army's Regiment of Mounted Rifles.  The revolver was also issued to the Army's "Dragoon" Regiments.  This revolver was designed as a solution to numerous problems encountered with the Walker Colt.  Although it was introduced after the Mexican-American War, it became popular among civilians during the 1850s and 1860s, and was also used during the American Civil War.

TT pistol: The TT-30 (Russian: "7,62-мм самозарядный пистолет Токарева образца 1930 года" , 7,62 mm Samozaryadnyj Pistolet Tokareva obraztsa 1930 goda, "7.62 mm Tokarev self-loading pistol model 1930", TT stands for Tula-Tokarev) is a Russian semi-automatic pistol.  It was developed in the early 1930s by Fedor Tokarev as a service pistol for the Soviet military to replace the Nagant M1895 revolver that had been in use since Tsarist times, though it ended up being used in conjunction with rather than replacing the M1895.  It served until 1952, when it was replaced by the Makarov pistol.

Webley–Fosbery Automatic Revolver: The Webley–Fosbery Self-Cocking Automatic Revolver was an unusual, recoil-operated, automatic revolver designed by Lieutenant Colonel George Vincent Fosbery, VC and produced by the Webley & Scott company from 1901 to 1924.  The revolver is easily recognisable by the zig-zag grooves on the cylinder.

Nirbheek: Nirbheek (lit.  "fearless") is a 6-shot cylinder revolver designed & manufactured by the Ordnance Factories Organization in Kanpur, India.

FN Barracuda: The FN Barracuda is a double-action multi-caliber revolver designed by FN Herstal.  It can be switched between three calibers (9×19mm, .38 Special and .357 Magnum) by changing parts of the cylinder.  FN decided to enter the revolver market, aiming to satisfy law enforcement customers on both sides of the Atlantic, and this gun represented their only attempt at doing so, in collaboration with Astra.  Production stopped around 1989 after poor sales.  The revolver itself is generally thought to be well-made, but it targeted a diminishing revolver market for law enforcement.

Colt Pocket Percussion Revolvers: The family of Colt Pocket Percussion Revolvers evolved from the earlier commercial revolvers marketed by the Patent Arms Manufacturing Company of Paterson, N.J.  The smaller versions of Colt's first revolvers are also called "Baby Patersons" by collectors and were produced first in .24 to .31 caliber, and later in .36 caliber, by means of rebating the frame and adding a "step" to the cylinder to increase diameter.  The .31 caliber carried over into Samuel Colt's second venture in the arms trade in the form of the "Baby Dragoon"-a small revolver developed in 1847–48.  The "Baby Dragoon" was in parallel development with Colt's other revolvers and, by 1850, it had evolved into the "Colt's Revolving Pocket Pistol" that collectors now name "The Pocket Model of 1849".  It is a smaller brother of the more famous "Colt's Revolving Belt Pistol of Naval Caliber" introduced the same year and commonly designated by collectors as the "1851 Navy Model" (and which was a basically a larger, .36 caliber of the Pocket Model, "belt pistol" referring to a weapon sized to fit into a belt holster, as opposed to the saddle holsters generally called for by Colt's larger cavalry combat models).  In 1855 Colt introduced another pocket percussion revolver, the Colt 1855 "Sidehammer", designed alongside engineer Elisha K. Root.

FitzGerald Special: The FitzGerald Special, "Fitz Special", or "Fitz Colt" is a snubnosed revolver modified for concealed carry.  The concept was pioneered by John Henry Fitzgerald (also known as J.H. Fitzgerald, J. Henry Fitzgerald, and "Fitz"), an employee of Colt Firearms from 1918 to 1944.  Fitzgerald was a well known and respected competition pistol shooter of the 1920s and 30s and a theorist and innovator of combat pistol shooting tactics.  In 1930, he wrote a book titled "Shooting", on the topics of pistol shooting techniques and tactics.  There are "authentic" Fitz Specials modified by Fitzgerald himself, though the term can more generally refer to any revolver with similar modifications.

Nagant M1895: The Nagant M1895 Revolver was a seven-shot, gas-seal revolver designed and produced by Belgian industrialist Léon Nagant for the Russian Empire.

Supporting paragraphs: TT pistol Nagant M1895
Answer: Léon Nagant