{"id":2484,"date":"2025-02-18T11:08:26","date_gmt":"2025-02-18T11:08:26","guid":{"rendered":"https:\/\/c3junkie.com\/?page_id=2484"},"modified":"2025-04-20T22:45:52","modified_gmt":"2025-04-20T22:45:52","slug":"9mm-ar15-m16-ported-sd-vs-non-ported","status":"publish","type":"page","link":"https:\/\/c3junkie.com\/?page_id=2484","title":{"rendered":"9mm AR15 \/ M16 Ported SD vs non-ported"},"content":{"rendered":"
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Someone gave me a straight blowback SD upper a long time ago.\u00a0 I have always reloaded 9mm 147Gr for all my 9mm guns so I didn’t have to keep different rounds for suppressed vs non-suppressed.\u00a0 I recently decided to re-core the old SD can.\u00a0 Mainly because it was straight blowback and I wanted to go with the CMMG RDB system.\u00a0 I started off with a stainless 5″ Odin Works that I modified for the CMMG RDB system and then gradually drilled ports till 115Gr Federal Blazer went subsonic.\u00a0 I stopped at 6 ports.\u00a0 During this process, I also happened to have a 4.5″ stainless barrel from another blank supplier that I chronographed out of curiosity.\u00a0 To my surprise, it was already subsonic.\u00a0 I do see that Ballistics by the Inch only lists two different 115Gr loads but they are hot self defense loads: http:\/\/www.ballisticsbytheinch.com\/9luger.html<\/a>\u00a0 I don’t see any testing for ‘cheap’ 115Gr ball ammo.<\/p>\n

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Here are some chronograph results with the 4.5″ stainless barrel above, left.\u00a0 Notice how slow the 124Gr Aguila is.\u00a0 All data below was with the Octane9 suppressor mounted.<\/p>\n\n\n\n\n\n<\/colgroup>\n\n\n\n\n\n\n\n\n
115Gr Blazer<\/td>\n124Gr Blazer<\/td>\n\n
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124Gr Aguila<\/div>\n<\/div>\n<\/td>\n
115Gr 4.2Gr Bullseye<\/td>\n<\/tr>\n
1050<\/td>\n1051<\/td>\n986<\/td>\n1005<\/td>\n<\/tr>\n
1055<\/td>\n1063<\/td>\n993<\/td>\n1007<\/td>\n<\/tr>\n
1022<\/td>\n1047<\/td>\n944<\/td>\n1020<\/td>\n<\/tr>\n
1059<\/td>\n1068<\/td>\n967<\/td>\n977<\/td>\n<\/tr>\n
1066<\/td>\n1053<\/td>\n1006<\/td>\n964<\/td>\n<\/tr>\n
1050.4 Avg<\/td>\n1056.4 Avg<\/td>\n979.2 Avg<\/td>\n994.6 Avg<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Thinking this may have been a fluke, I got a second 4.5″ barrel from a different blank manufacturer (Green Mountain).\u00a0 I tested using the same lot of 115Gr Blazer.\u00a0 This time, higher velocities than the first barrel but here in Florida, it is still barely subsonic.\u00a0 Probably not subsonic in northern states or higher altitudes.\u00a0 https:\/\/www.weather.gov\/epz\/wxcalc_speedofsound
\n<\/a>According to the link above, 80 Degree’s F the speed of sound is 1138.52
\nData below is also with Octane9 mounted.<\/p>\n\n\n\n\n<\/colgroup>\n\n\n\n\n\n\n\n\n
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115Gr Fed Blazer<\/div>\n<\/div>\n<\/td>\n
124Gr Blazer<\/td>\n\n
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115Gr 4.2 Bullseye<\/div>\n<\/div>\n<\/td>\n
124Gr 4.2 Bullseye<\/p>\n
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<\/div>\n<\/div>\n<\/td>\n
\u00a0124Gr 3.7 Titegroup<\/td>\n<\/tr>\n
1094<\/td>\n1105<\/td>\n1077<\/td>\n997<\/td>\n935<\/td>\n<\/tr>\n
1117<\/td>\n1091<\/td>\n1062<\/td>\n1016<\/td>\n918<\/td>\n<\/tr>\n
1072<\/td>\n1059<\/td>\n1076<\/td>\n1028<\/td>\n953<\/td>\n<\/tr>\n
1106<\/td>\n1103<\/td>\n1043<\/td>\n993<\/td>\n949<\/td>\n<\/tr>\n
1134<\/td>\n1088<\/td>\n1024<\/td>\n1017<\/td>\n946<\/td>\n<\/tr>\n
1104.6 Avg<\/td>\n1089.2 Avg<\/td>\n1056.4 Avg<\/td>\n1010.2 Avg<\/td>\n940.2 Avg<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Pictured below is the 4.5″ 3 lugged barrel and it is super short and very lightweight.\u00a0 Going with a non-ported allows you to quickly change to different suppressors with varying levels of performance and backpressure.\u00a0 While there are several SD cans out there, they are all designed for a specific barrel and will most likely be longer than below.<\/p>\n

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An argument could be made that the SD has better weight distribution being less front heavy but in the picture above, that setup is super light and not front heavy at all.<\/p>\n

A ported setup ‘may’ be softer shooting but I cannot tell a difference at this time.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

Someone gave me a straight blowback SD upper a long time ago.\u00a0 I have always reloaded 9mm 147Gr for all my 9mm guns so I didn’t have to keep different rounds for suppressed vs non-suppressed.\u00a0 I recently decided to re-core the old SD can.\u00a0 Mainly because it was straight blowback and I wanted to go …<\/p>\n

9mm AR15 \/ M16 Ported SD vs non-ported<\/span> Read More »<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-2484","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/c3junkie.com\/index.php?rest_route=\/wp\/v2\/pages\/2484","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/c3junkie.com\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/c3junkie.com\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/c3junkie.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/c3junkie.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2484"}],"version-history":[{"count":10,"href":"https:\/\/c3junkie.com\/index.php?rest_route=\/wp\/v2\/pages\/2484\/revisions"}],"predecessor-version":[{"id":2625,"href":"https:\/\/c3junkie.com\/index.php?rest_route=\/wp\/v2\/pages\/2484\/revisions\/2625"}],"wp:attachment":[{"href":"https:\/\/c3junkie.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2484"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}