mofosheee Posted September 6, 2022 Share Posted September 6, 2022 Hello BE forum Seeking a starting load for; H&K Mp5 8.5"(ish) barrel with suppressor @ 7500' elevation. The 7500' ele is what gets me. I've never made adjustments for 7500' For powder my options are; AA#2, AA#5, W231 (HP38) and Titegroup. 147gr RN Berry's as a projectile. Of course I want to stay subsonic around 1000fps. Any and all advice appreciated. Yes, I will chrono. Thank you! Quote Link to comment Share on other sites More sharing options...
iflyskyhigh Posted September 7, 2022 Share Posted September 7, 2022 Speed of Sound Calculator Speed of sound has more to do with temperature than pressure altitude. 3.5 grs of TG is my sub load with 147 gr plated (one of the few areas where I’ve gotten exceptional accuracy from plated bullets). That’s my go to load. HP38 when i had it was about 3.7-3.8 for sale velocity. Custom built AR-9 with 5” suppressed barrel is right around 960. Plug some number in Quote Link to comment Share on other sites More sharing options...
Orlandoech Posted September 21, 2022 Share Posted September 21, 2022 (edited) I have an MP5A2 suppressed and this is my 147gr load data in Utah at 4400 ft ele. Your AA2/5 are close to burn rates of N340 and W244. Let me know if you can or read it and I can email it to you. Edited September 21, 2022 by Orlandoech Quote Link to comment Share on other sites More sharing options...
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