workingmanjeff Posted February 11, 2023 Share Posted February 11, 2023 Just started reloading 300 blackout subsonic, have been using standard primers, any benefits to using magnums instead Link to comment Share on other sites More sharing options...
NOSHMJ Posted February 12, 2023 Share Posted February 12, 2023 Not really. If thats all you have, go for it. You may have to reduce your charge down a bit is all. Link to comment Share on other sites More sharing options...
looking4reloadingdeals Posted February 14, 2023 Share Posted February 14, 2023 Iv always used CCI reg SRP and never had any problems Link to comment Share on other sites More sharing options...
K-Tex Posted April 3, 2023 Share Posted April 3, 2023 I use both type, but switched to mag only when using 296, h110 and lil gun. It holds about the same amount of powder as 44mag which I use mag primers in it also. Link to comment Share on other sites More sharing options...
willfully armed Posted August 30, 2023 Share Posted August 30, 2023 There is no benefit to using magnum primers in 300blk. Link to comment Share on other sites More sharing options...
K-Tex Posted September 9, 2023 Share Posted September 9, 2023 On 8/30/2023 at 10:11 AM, willfully armed said: There is no benefit to using magnum primers in 300blk. I use 450's due to the powder and bullet weights used. As far as more speed there wasn't any/enough change. @ primers used for comparing loads I've done are 400's and 450's. If it works for me, then I go for it. Link to comment Share on other sites More sharing options...
HesedTech Posted September 10, 2023 Share Posted September 10, 2023 The answer is, it really won't change your accuracy... much. In high power rifle the real difference will be found in changing brands of primers. There's lots of testing of this idea on YouTube and worth a watch. Here's a great video from a reloader testing the same brand of primers, CCI. Basically Magnum are harder cups and if you are pushing the max pressures you need to test your loads when changing brands or types. Link to comment Share on other sites More sharing options...
K-Tex Posted September 14, 2023 Share Posted September 14, 2023 Testing of 1 powder-bullet-seating depth combo can be misleading on this video and in actual. Also in different guns even if they're the same make and model. Still interesting on his testing. Link to comment Share on other sites More sharing options...
willfully armed Posted October 9, 2023 Share Posted October 9, 2023 On 9/9/2023 at 3:39 PM, K-Tex said: I use 450's due to the powder and bullet weights used. As far as more speed there wasn't any/enough change. @ primers used for comparing loads I've done are 400's and 450's. If it works for me, then I go for it. I've loaded about every offering for the BO, subs to supers, light to heavy... and for s#!ts and grins, standard and magnum primers. I've not seen a single instance of improvement over a standard primer, when a magnum was used. Thereby, I've not seen any need to use a component not intended for the caliber. Link to comment Share on other sites More sharing options...
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