subsonic 308 loads

[Ds J]

A good reason to try it?

[Againstthegrains]

A bit off topic, but relevant.

Lead is significantly heavier than copper in terms of density.

Lead density: ~11.34 g/cm³

Copper density: ~8.96 g/cm³


So, for the same volume, lead will weigh roughly 1.27 times more than copper.

Roughly, a 150gr copper bullet will have the same volume as identical 190gr lead bullet.

But since most "lead" bullets have a copper cup and lead core, the ratio is less depending on the amount of gilding metal (95% copper zinc alloy) used in construction. So more like 1.2 times the volume, making a 150gr cup and core closer to a 180gr mono metal copper bullet. If you add plastic tips and cannulas and things, the ratio is potentially even less. Obviously design and bearing surface have an effect on stability in relation to twist ratio, but even if you go to a 130gr mono, the bullet volume and approximate bearing surface is that of a 150gr cup and core bullet, which stabilizes well in anything from a 1:10 to 1:13 twist barrel.

Going even lighter, a brass bullet (think Impala or Viper plains gold) will be even bigger in volume. A 132gr brass bullet is made from the same cut as a 140gr copper bullet, which is equivalent in volume to a 168gr bullet.

So going back to subsonics, a friend of mine suggested I use a 250gr bullet, so that most of the bullet will sit within the case volume, and help negate the need for fillers, as the space is filled by the bullet, and the remaining space is filled with the necessary powder to shift the heavy bullet. I just wonder how such a long bullet will stabilize at 800ft/sec from a 1:10 twist barrel, and weather it even matters on a live target?

[JamesNotBond]

Treeman had some very interesting quiet ammunition some years back, I recall we shot bricks with them. The results on the bricks were not impressive, some did not even break.

[Tripodmvr]

Less charge with a heavier bullet will assist in keeping the bullet subsonic. This should also give better penetration as momentum is higher. A 1 in 10 twist barrel should easily stabilize a 220gr bullet. The 250gr would have to be a flat pointed bullet to keep the length as short as possible. Lead bullets out of a large caliber revolver achieve incredible penetration through animal tissue.

[Treeman]

I could not get a 220 gr bullet to subsonic stabilize, they all key-holed. I only got 165 and 170 ? gr bullets one hole accurate - I even battled with 180 gr, it all worked alright but grouping was "iffy", but 170 gr? Frontiers were brilliant,  I will try again now that I have a .308 again.

[Tripodmvr]

I could not get a 220 gr bullet to subsonic stabilize, they all key-holed. I only got 165 and 170 ? gr bullets one hole accurate - I even battled with 180 gr, it all worked alright but grouping was "iffy", but 170 gr? Frontiers were brilliant,  I will try again now that I have a .308 again.

Just check your barrel twist rate.
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Last 308 was Israeli K98 mauser, this is a Musgrave, it will also be 1-10 twist

[223]

Just for reference, a friend built a subsonic load for his 300BLK Remington with 16" 1:7" twist barrel, suppressed.

He decided on a 220gn PMP bullet, as these were available.

Performance on paper was excellent, with small groups at 1000fps.

Terminal performance on the bushpigs was dismal.  The bullets zipped straight through with almost invisible exit wounds and no blood trail.  Some pigs, supposedly with decent hits in the vitals, were lost in the thick bush.
Not happy with this, he switched to 110gn Barnes X type bullets at around 2400fps and the pigs all dropped in their tracks.  Sound signature was louder, but that was a necessary compromise.

My personal preferred tool for this kind of job is a suppressed 44 Mag rifle, loaded with 320gn flat-nosed cast lead (and powder coated) bullets at 1000fps.  These also don't expand, but cut a decent wound channel and mostly exit, except on frontal shots on big animals.  Shot placement is still critical. Ideally you need to hit some bone, like skull (brain), the spine or at least front leg bones.  Lung shots are not effective and heart shots only slightly better.  Keep that in mind when trying smaller calibers.

I still think a bow with broad head tip on the arrow is far more deadly.  Also pretty quiet.

[Treeman]

Just for reference, a friend built a subsonic load for his 300BLK Remington with 16" 1:7" twist barrel, suppressed.

He decided on a 220gn PMP bullet, as these were available.

Performance on paper was excellent, with small groups at 1000fps.

Terminal performance on the bushpigs was dismal.  The bullets zipped straight through with almost invisible exit wounds and no blood trail.  Some pigs, supposedly with decent hits in the vitals, were lost in the thick bush.
Not happy with this, he switched to 110gn Barnes X type bullets at around 2400fps and the pigs all dropped in their tracks.  Sound signature was louder, but that was a necessary compromise.

My personal preferred tool for this kind of job is a suppressed 44 Mag rifle, loaded with 320gn flat-nosed cast lead (and powder coated) bullets at 1000fps.  These also don't expand, but cut a decent wound channel and mostly exit, except on frontal shots on big animals.  Shot placement is still critical. Ideally you need to hit some bone, like skull (brain), the spine or at least front leg bones.  Lung shots are not effective and heart shots only slightly better.  Keep that in mind when trying smaller calibers.

I still think a bow with broad head tip on the arrow is far more deadly.  Also pretty quiet.

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You have stated the absolute facts.
Subsonic =
Bigger calibre is better x 10
Flat faced lead is better than any expanding bullet, and bigger calibre is better
You MUST break bone (even head shots "duh!")
You must break bone, bigger is better and flat faced beats them all ---------------- and its still a kak idea.
 

[Ds J]

One area where this comes in handy is for culling in/near built areas. My brother helped with culling on an eco estate - a subsonic .22 cartridge causes too much trouble with insufficient penetration or too little damage.