That is what EnCon enforces for hunting. There may be a town ordinance that is the same or even stricter for firearm discharges in general. Call your local PD for clarification? I would be interested in the answer they give.

Does this not apply?...

500 Foot Zone - It is prohibited to hunt with, shoot, or carry a loaded firearm within 500 feet of any building occupied by people or domestic animals, or used for storage of flammable material, or within 250 feet of such buildings when waterfowl hunting in tidal areas from land shooting positions or from floating blinds anchored adjacent to land or from rock positions, unless written permission for lesser distances is obtained from the owner and carried.

the 500 foot rule does not apply if he is target shooting. If it bothers you that much amend the lease and tell him to stop.

What you quoted is from the Hunting Regulations and is not intended to control target shooting, it specifies the "Behavior and actions of hunters":

HUNTING AND TRAPPING
26-66-1. Behavior and actions of hunters
(a) The method of taking wild birds and wild quadrupeds by hunting shall be restricted to firearms, high velocity air guns using a single ball or pellet type projectile, and compound, long, or recurved bow. In designated areas, by special permit, the commissioner may allow the use of modified versions of air guns or archery implements to achieve wildlife management objectives. No arrow or projectile which is coated with or contains any drugs, poison or known tranquilizing substance may be used or possessed while engaged in archery hunting.

(b) Use of crossbows is prohibited, except that a person who has a permanent physical disability to the degree that he or she cannot operate a long, recurve or compound bow may obtain a permit to take deer or turkey with a crossbow. A person applying for this permit must show proof that he or she has successfully completed the Connecticut conservation education/firearms safety advanced bowhunter education course or its equivalent, and must personally appear before the commissioner, or his designee, with certification from a licensed physician that he or she is so disabled. Upon satisfactory proof of disability, the commissioner may issue such a permit under this section which must be carried at all times while hunting. Such permit shall not be a replacement for and is valid only with any license or permit required for archery hunting under the provisions of chapter 490 of the Connecticut General Statutes or regulations promulgated thereunder. Any crossbow and bolt combination to be used for hunting as permitted under this subsection shall meet the following specifications: (1) The draw weight of the crossbow shall be not less than 125 pounds nor more than 200 pounds; (2) The crossbow shall have a permanent fixed rifle type stock, and a functional and/or fully operational mechanical safety device; (3) The bolt (arrow) length shall be not less than eighteen inches, excluding the broadhead; (4) The bolt weight shall be not less than 450 grains, including the broadhead; (5) the broad head shall have two or more blades with a width not less than seven-eighths of an inch at the widest point. In addition, any crossbow in a drawn and cocked position shall be considered a loaded weapon, whether or not a bolt is loaded on the crossbow.

(c) There shall be no hunting from one-half hour after sunset to one-half hour before sunrise, except that raccoon and opossum hunting is permitted after sunset on state-owned lands which are open to hunting and on privately owned lands where landowners have granted permission, and provided the open season for hunting migratory game birds shall be governed by the provisions of Section 26-66-4, and provided further that on the third Saturday in October, hunting shall commence at 7:00 a.m. e.d.t. (Eastern daylight time) except for waterfowl, turkey and archery deer hunting.

(d) There shall be no hunting with firearms, discharging of firearms or carrying of loaded firearms within five hundred feet of any building occupied by people or domestic animals or used for storage of flammable or combustible materials, unless written permission of owner of such buildings is obtained and carried while hunting to allow closer shooting distances, except that the above referred to distance shall be not less than two hundred fifty feet unless written permission of owner of such buildings is obtained and carried while hunting to allow closer shooting distances when waterfowl is hunted in tidal water areas from land shooting positions or from floating blinds anchored adjacent to land or from rock formations. The provisions of this subsection shall not apply to landowners, their spouses or lineal descendants when hunting within five hundred feet of buildings owned by them or, when hunting waterfowl, within 250 feet of such buildings, but shall apply when said persons are hunting within said distances of buildings not so-owned.

(e) No hunting weapon shall be discharged toward any person, building or domestic animal when the same is within range or from or across the traveled portion of any public roadway.

(f) Domestic animals, agricultural crops, signs, fences, installations and facilities of utility companies and other property shall not be damaged