Subsonic 260's
- Thread starter jambau
- Start date
I actually am playing around with this, although the project is currently on hold. I came up with a subsonic load for my .308, so I wanted to play with the .260 too.
In the .308, with an 18" barrel, my load was Sierra 180 Round Nose bullets, 10.1gr Trailboss, Lake City Brass and standard Federal Primers. I assumed that I could lower the Trailboss charge to somewhere between 7-9gr and work with the 140 ELDs to see if they would go subsonic and stabilize. What I found was that at my lowest initial charge of 8ish (can't recall at this point, it has been a few months), the bullets were still breaking the sound barrier.
I don't want to lower my powder charge too much farther and risk not having enough of the case volume filled, so next step is a heaver bullet. I think someone is making some 160gr bullets, and a round nose would be ideal because they almost always stabilize (boat tailed bullets need velocity).
Hope this helps, if you make any progress let me know!
In the .308, with an 18" barrel, my load was Sierra 180 Round Nose bullets, 10.1gr Trailboss, Lake City Brass and standard Federal Primers. I assumed that I could lower the Trailboss charge to somewhere between 7-9gr and work with the 140 ELDs to see if they would go subsonic and stabilize. What I found was that at my lowest initial charge of 8ish (can't recall at this point, it has been a few months), the bullets were still breaking the sound barrier.
I don't want to lower my powder charge too much farther and risk not having enough of the case volume filled, so next step is a heaver bullet. I think someone is making some 160gr bullets, and a round nose would be ideal because they almost always stabilize (boat tailed bullets need velocity).
Hope this helps, if you make any progress let me know!
I would think this is a lot harder to accomplish with a more over bore cartridge like a .260
Isn't there a risk if getting too much fast burning powder and developing a nasty pressure spike trying to push it out a 6.5 bore?
just a thought I have heard with 5.56
Isn't there a risk if getting too much fast burning powder and developing a nasty pressure spike trying to push it out a 6.5 bore?
just a thought I have heard with 5.56
to be honest, I hadn't thought of that. When I shot the loads I had, they didn't seem to hiccup or anything, but they were definitely supersonic by at least a couple of hundred fps.
So I've been loading the 160gr. round nose Hornady over 9.5gr. of Trail boss. 10grs went supersonic. I haven't had any issues except for accuracy. I've taken it out to 100 yards and got about 5-6 inch groups. Not stellar accuracy but man is it fun! I posted the question in a suppressor thread about accuracy expectations. Has anyone tried anything different?
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