Testing Results - Subsonic Rounds For HK SP5


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Special Hen Supporter
Sep 1, 2012
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I got some N320 powder in the other day, with the intent on trying something a little faster burning than my regular go-to pistol powder (CFE-Pistol), to try to find a good recipe for my HK SP5 while shooting suppressed.

I got several test loads worked up and made it to the range this afternoon. I found a pretty good node and was very pleased with the results.

Loading RMR 147gr round nose FMJ's, Vihtavuori N320 powder with a COAL of 1.150, I found a good node from 3.6gr to 3.8gr. Here's snapshot on the chrono data at 3.7gr. This is towards the max of the published VV load data, but the brass was still showing zero pressure signs, not even a hint of flattened primers, etc.


If it wasn't for shot #3 being a tad slower, the SD and Spread #'s would be even better (4.4 SD and 11 ES). Be that as it may, I'll take a single digit standard deviation from a pistol load all day. I'm happy to report the faster burning N320 seemed to run a lot cleaner with a can on the HK. I was especially pleased that I got zero gas to the face when shooting all loads of the N320, which for me as a lefty is huge!

All in all, I'm super pleased with the performance of the N320 and now understand why a lot of folks are using it for their suppressor loads.

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