Another Timely Question about שהחיינו and תתחדש

After the massacres near Gaza, and the subsequent massive demonstrations in many large American cities, which volubly and proudly encourage the torture and murder of Jews, this has become relevant. Judging by the fact that there is almost a minyan at my local gun shop whenever I've walked in during the past couple of weeks, I'm not the only one.

Do you make a "Shehechiyanu" on a new firearm, such as a pistol or rifle? If someone shows you his new shotgun, do you wish him "Oy, vee shein! Tischadesh!" ?

Everyone who reads this is knowledgeable enough to make his own decision. What I offer is this list of considerations to bear in mind.

1. YD 28:2

הגה מי ששחט פעם הראשון מברך שהחיינו על הכיסוי אבל לא על השחיטה דמזיק לבריה (במנהגים ישנים בשם ר' ידידיה משפירא):

Darkei Moshe there

 והטעם שמברכין על הכיסוי ולא על השחיטה משום דבשעת השחיטה מקלקל בריה אחת אבל בכיסוי הוי מתקן ע"כ מצאתי

Let me point out that even though we do not make a shehechiyanu on Shechita, as per the Rema, I can't imagine that anyone would say you don't make a shehechiyanu when you buy a beautiful new chalef.  A good chalef is a treasure, besides being expensive, and getting a good one is a special occasion.

2.  OC 223

מת אביו מברך דיין האמת היה לו ממון שיורשו אם אין לו אחים מברך גם כן שהחיינו ואם יש לו אחים במקום שהחיינו מברך הטוב והמטיב:

3. Ran and Baal Hamaor end of Pesachim and Teshuvos Harashba 126, no Shechechiyanu on Sefiras HaOmer because while it is a mitzva, it brings no joy, only agmas nefesh. 

First, that idea might only apply to mitzvos, not to physical things, as you see in the case of yerusha. What the svara to be mechaleik is I do not know, but that seems to be true. Second, there, there is no hana'ah at all. Here, there is hana'ah of protecting yourself and others.

4. The Rosh in the eighth perek of Bechoros, and the Meiri on 133b, and many others, bring a dei'ah attributed to Rabbeinu Tam that you don't make a shehechiyanu at a bris משום צערא דינוקא, probably because the tzaaar makes the parents sad. Other rishonim (like Tos Sukkah 46a) clearly disagree, because they only apply this factor to שהשמחה במעונו.  This distinction was also pointed out by the Rashba in Tshuvos 1:245.

5. Shabbos 63a, a weapon is a davar meguneh.

לא יצא האיש לא בסייף ולא בקשת ולא בתריס ולא באלה ולא ברומח. ואם יצא — חייב חטאת. רבי אליעזר אומר: תכשיטין הן לו. וחכמים אומרים: אינן אלא לגנאי, שנאמר: ״וכתתו חרבותם לאתים וחניתותיהם למזמרות ולא ישא גוי אל גוי חרב ולא ילמדו עוד מלחמה

Reb Moshe (OC IV:81) distinguishes swords from the pagers worn by Hatzolah.  I can't think of any reason to distinguish a firearm from a sword, so according to the Chachamim, a gun is a genai, not a tachshit. But as far as I know, being a genai is not a reason to not make a shehechiyanu. If you are grateful that you have it, if it serves an important purpose, you make a shehechiyanu. Like a laundry machine.

6. It could be said that the word שהחיינו is particularly appropriate for an instrument which was purchased specifically to preserve your life or the life of your loved ones. However, the nusach of the bracha is generally thought to pertain to the present moment - Thank you, Hashem, for letting me live to see this moment, allowing me to acquire this object/do this mitzvah. It is a ברכת השבח for זמן הזה, not a tefilla for the future. 

As an additional consideration, כבר הלכו בה הנמושות on whether the bracha Shehechiyanu in general is a רשות or a חובה.

ערו"הש רכ"ה:ה לחלק בין הבאים מזמן לזמן להשאר (which works well with Eiruvin 40b)

רמ"א רכ"ג:א

משנ"ב רכ"ה ס"ק ט

בה"ל סימן רי"ט סעיף ד

שבט הלוי חלק ד ס' כה