6/24/2023 0 Comments Subsonic 7.62x39 loads![]() ![]() Highly dangerous excessive pressures as the fire builds up behind it, isĪs high as it is in any big magnum being loaded light with heavy bulletsĪnd slow powder. Microseconds only half engaged with the rifling, which can lead to The possibility of getting a bullet stuck for a few wrote:The 6.5 Creedmoor is one of those cartridges I would be carefull of when knapper On Friday,įebruary 28, 2020, 06:14:02 PM MST, Larry Bump Larry I am very interested in the development of the sub-sonic AR 15Īnd if it will preform as a true SUB-SONIC then i intend onĮxperimenting with my 6.5 Creed moor. On Sunday 01 March 2020 12:56:01 Dallas Richardson via Groups.Io wrote: The 180 grain round nose bullets seem to work better though, so that would be my suggested starting place. They are both accurate, with the Matchkings being exceptionally so. Both of these loads hit 12 to 14 inches lower than standard Wolf ammo at 100 yards. I use a Lee factory crimp on these, and crimp them med+. I had to open the adjustable gas block to 13 of 20 clicks. 11.5 gains of Accurate 5744 with a 174g Sierra MatchKing is also subsonic but requires more gas to cycle the AR. 11.5 gains of Accurate 5744 with a 180g bullet (I used Speer round nose soft points). This rifle has an adjustable gas block, but the 180 grain subsonic rounds cycle with it halfway open 10 out of 20 clicks. I was using a sturdy 9mm suppressor for testing. Those two shots did cycle though, ejecting and chambering the next round. I didn't mess with it without the suppressor beyond the first two test shots. This works reliably with a suppressor, but it did *want* to cycle without one. What I found was Accurate 5744 will push out a 180 grain bullet at subsonic speeds and still cycle an AR-15 with a 16" barrel. ![]() So I bought a new set of dies (I sold the last set after giving up) and tried a few different powders. Recently I had the urge again, It was either get this working or buy a 300 AAC. Considering the extra volume taken up by the bullet.I had been messing with the "Subsonic 7.62x39 in an AR platform" subject for a while and gave up after finding minimal success. If I recall, these Russian cartridges have like 22gn of powder in them. Plus the bigger 174gn bullet taking up more volume in the casing. All load data have a minimum and maximum. Plus, heavy bullets call for a lower powder charge anyway. But with the short barrel and heavy bullet, a standard charge would be pushing it at around 1700fps. You might want to investigate something called Secondary Explosion Effect. What do your manuals say about reducing Smokeless rifle powder charges below "tested" minimums? It is easy to work up loads out in the field. I think this should give it extra pressure to cycle as opposed to pistol powder that has a pressure drop by the time it gets to the carbine gas port. The bigger bullet takes up more volume in the case anyways and with a 10.5" barrel, you get that velocity drop you need to get closer to subsonic. I wonder if using the standard rifle powder but just less of it will work too. The casing would short stroke and go back into the chamber un-suppressed. It would be interesting to see if it will cycle :O. I did not have the concentricity rod on hand so I did not try it suppressed. Other subsonic loading data of ours can be found here: We got 1050FPS consistently at 65 degree temperature. 2.20" OAL (max for x39, left room for possible bullet setback.03" left before neck goes over into tapered bullet) ![]()
0 Comments
Leave a Reply. |