Dear Rabbi, Please give me halachik understanding for allowance to carry a gun on shabbos. Are we allowed to carry on Shabbos? Thank you.

The prohibitions to be discussed regarding carrying firearms on Shabbat are as follows; the prohibition of Muktzeh (Items which may not be moved or handled on Shabbat), the prohibition of carrying from one domain to another, and the prohibiting of carrying out of Techum Shabbat (the Limit on Travelling more than 2000 cubits outside of a Town on Shabbat). Regarding the prohibition of Muktzeh there is a discussion among Halachic authorities whether this is considered a Keli Shemelachto L'isur (a utensil whose primary use is forbidden) because it's made to shoot with, or is it considered a Keli Shemelachto L'Heter (a utensil whose primary use is permitted) due to the fact that carrying it is intended as a threat. Therefore where there is no need, initially one should not carry arms even where there is an Eruv (a public area surrounded with walls, or poles and wiring, in order to turn it into one private domain where it is permitted to carry) unless it is for the purpose of the Keli itself or its placement as per the law of a Keli Shemelachto L'isur. In a case where it is necessary one can be lenient and carry arms where there is an Eruv as per the law of a Keli Shemelachto L'Heter .In a case where it is necessary due to fear of danger it is permitted to carry arms even outside the Eruv, and even to a Reshut Harabim (a public domain), and even beyond Techum Shabbat. If possible, one should carry the gun wearing it, which means strapped over his shoulder or a pistol holstered on his belt, in order to minimize Shabbat violation as much as possible. (שש"כ מהדורה מחודשת פרק כ סעיף יב הערה כט ופרק מא סעיף לא, שולחן שלמה ח"ב סי' שח ס"ק טז ד"ה מ"מ..., ושם ס"ק כז, ערוה"ש סימן שא סעיף נא, וע"ע תחומין ד 227, 236, 923).