<entry id="2229783" stat="A" corpus="jmdict" type="jmdict">
<ent_corp type="jmdict">jmdict</ent_corp>
<ent_seq>2857899</ent_seq>
<k_ele>
<keb>片舷斉射</keb>
</k_ele>
<r_ele>
<reb>へんげんせいしゃ</reb>
</r_ele>
<sense>
<pos>&n;</pos>
<field>&mil;</field>
<misc>&hist;</misc>
<gloss>broadside (firing of all the guns on one side of a warship)</gloss>
</sense>
<info>
<audit time="2023-04-30 13:02:33" stat="A" unap="true">
<upd_name>Brian Krznarich</upd_name>
<upd_email>...address hidden...</upd_email>
<upd_detl>Not trying to remove entries just for the sake of it.  

片舷斉射 entry was the most common form I found on the now-deleted 半舷砲 entry. 

reverso translates this as "broadside", and also doesn't seem to have any better Japanese translations for broadside in reference to firing guns from a battleship.

if you search google for "片舷斉射" and "broadside" (or "fire a broadside") together,  you'll see this noted in various references.

dictionary references report this as をする, and examples also use を行う, neither of which we have notes for. (ngrams agree)

deleted reference was "broadside fire", but it appears that the english gloss should just be "broadside", with 片舷斉射をする becoming "fire a broadside". The simple gloss would then need some clarification in an [expl] or parens. The [expl] feels like the most readily comprehensible approach, but maybe is more verbose than we'd like.

More general and figurative uses of "broadside" appears to be handled by 一斉攻撃. ("b(悪口の)一斉攻撃.").  

I initially simplified "a firing of all guns" to "firing all guns".... but I guess a "broadside" is in fact a single volley.</upd_detl>
<upd_refs>Oxford Languages · Learn more
noun: broadside; plural noun: broadsides
1.a fierce verbal attack.
2.
HISTORICAL
a. a firing of all the guns from one side of a warship. &lt;- 片舷斉射 is only this one
b. the set of guns which can fire on each side of a warship.
c. the side of a ship above the water between the bow and quarter.

Actually have several reverso instances of this one.  This seems to be the correct term for the battleship usage.
https://context.reverso.net/%E7%BF%BB%E8%A8%B3/%E8%8B%B1%E8%AA%9E-%E6%97%A5%E6%9C%AC%E8%AA%9E/broadside#%E7%89%87%E8%88%B7%E6%96%89%E5%B0%84

https://ejje.weblio.jp/content/broadside
舷側、片舷斉射、(悪口の)一斉攻撃

研究社 新英和中辞典での「broadside」の意味
broadside
アクセント・音節bróad・sìde 発音を聞く
1【航海, 海語】 舷側.
2a片舷斉射.
b(悪口の)一斉攻撃.

This blog shows usage and confirms the reading. 
https://ameblo.jp/economirai88/entry-12648261685.html
戦艦ドレッドノートの基本諸元は、満載排水量２万１千トン余り、３０ｃｍ連装主砲５基搭載、最大装甲厚約２８ｃｍ、最大速力時速２１ノットでありました。主砲塔２番基、３番基は、艦橋横近辺に平行に備え付けられましたが、片舷（へんげん）斉射（せいしゃ）の場合には、４基８門の砲が敵を狙い撃つ能力を備えています。

https://www.wordreference.com/enja/broadside
broadside n	(military: gun attack from the side)	片舷斉射 名
 	The battleship fired a broadside on the enemy ship.
 

Here is a completely modern manga reference. If the subject is historic naval warfare, this seems to be a relevant term.
https://www.sbcr.jp/product/4797356328/
あなたのハートに片舷斉射！ 男女比 １：２００の船上で繰り広げられる「ボーイ・ミーツ・ガールズ」ストーリー！！


34 yourei examples:
https://yourei.jp/%E7%89%87%E8%88%B7%E6%96%89%E5%B0%84

Also verifies the へんげん reading for the 1st half (with matches the 1940s U.S. Military Reference):
nipponica. 海戦（海上で行う戦闘） maritime war
https://kotobank.jp/word/%E6%B5%B7%E6%88%A6%28%E6%B5%B7%E4%B8%8A%E3%81%A7%E8%A1%8C%E3%81%86%E6%88%A6%E9%97%98%29-1515671
...戦術運動や片舷(へんげん)斉射などをもって...</upd_refs>
</audit>
<audit time="2023-04-30 21:54:19" stat="A">
<upd_uid>jwb</upd_uid>
<upd_name>Jim Breen</upd_name>
<upd_email>...address hidden...</upd_email>
<upd_detl>No need to explain the gloss.</upd_detl>
<upd_refs>片舷斉射	213
新編英和活用大辞典, RP</upd_refs>
<upd_diff>@@ -11,0 +12 @@
+&lt;field&gt;&amp;mil;&lt;/field&gt;
@@ -14 +14,0 @@
-&lt;gloss g_type="expl"&gt;a firing of all guns from one side of a warship&lt;/gloss&gt;</upd_diff>
</audit>
<audit time="2023-05-01 15:44:43" stat="A" unap="true">
<upd_uid>robin1354</upd_uid>
<upd_name>Robin Scott</upd_name>
<upd_email>...address hidden...</upd_email>
<upd_detl>"Broadside" also refers to the guns themselves.</upd_detl>
<upd_refs>https://en.wiktionary.org/wiki/broadside#Noun</upd_refs>
<upd_diff>@@ -14 +14 @@
-&lt;gloss&gt;broadside&lt;/gloss&gt;
+&lt;gloss&gt;broadside (firing of all the guns on one side of a warship)&lt;/gloss&gt;</upd_diff>
</audit>
<audit time="2023-05-01 23:01:23" stat="A">
<upd_uid>jwb</upd_uid>
<upd_name>Jim Breen</upd_name>
<upd_email>...address hidden...</upd_email>
<upd_detl>OK</upd_detl>
</audit>
</info>
</entry>