I developed a load for my 308 with 173gr LRN bullets with MP200. It is the only Somchem powder which can safely be used for this application, according to a Somchem technician I once spoke to. I don't know about imported powders.

An old, very experienced hunter who culled substantially with subsonic cartridges told me to keep the speed at 800fps - 1000fps. His reason was that the cartridge speeds vary too much due to atmospheric influences, and that 800-1000fps stays stable.

I loaded in 0.5gr increments from 10.5gr down to 4.5gr, and settled on 4.8gr for 900fps.

Some averages:

10.5gr - 1482fps

8.5gr - 1294fps

6.5gr - 1097 fps

4.5gr - 853fps

I stuffed ½ a block of two ply toilet paper on top of the powder.

The LRN bullet pushes into the lands.

If memory serves correct the trajectory was something like spot-on at 20m, 2" high at 40m, spot-on at 60m and 2" low at 70m.

Treeman has experience with this as well - he will probably chime in as soon as he sees that I have posted ... someone needs to check me up 😉 😉

Last things for now:
- Going close to and over the sound barrier has a negative effect on accuracy,
- Remember that subsonic ammo has very little shock effect, if any at all. It just pokes holes, hence accurate shot placement is very important.

I developed a load for my 308 with 173gr LRN bullets with MP200. It is the only Somchem powder which can safely be used for this application, according to a Somchem technician I once spoke to. I don't know about imported powders.

An old, very experienced hunter who culled substantially with subsonic cartridges told me to keep the speed at 800fps - 1000fps. His reason was that the cartridge speeds vary too much due to atmospheric influences, and that 800-1000fps stays stable.

I loaded in 0.5gr increments from 10.5gr down to 4.5gr, and settled on 4.8gr for 900fps.

Some averages:

10.5gr - 1482fps

8.5gr - 1294fps

6.5gr - 1097 fps

4.5gr - 853fps

I stuffed ½ a block of two ply toilet paper on top of the powder.

The LRN bullet pushes into the lands.

If memory serves correct the trajectory was something like spot-on at 20m, 2" high at 40m, spot-on at 60m and 2" low at 70m.

Treeman has experience with this as well - he will probably chime in as soon as he sees that I have posted ... someone needs to check me up 😉 😉

Last things for now:
- Going close to and over the sound barrier has a negative effect on accuracy,
- Remember that subsonic ammo has very little shock effect, if any at all. It just pokes holes, hence accurate shot placement is very important.

Thanks, that's very helpful, and a good starting point.

Out of curiosity, what do you think would work better? large rifle primers or small rifle primers from palma brass?

- Remember that subsonic ammo has very little shock effect, if any at all. It just pokes holes, hence accurate shot placement is very important.

Yes, very important. I was looking at either using a .204 with 32gr at 3800ft/s or developing sub sonic 308. The .204 will still give a sonic crack, but is a very quiet rifle and at that speed, has 3x the energy.

What I found fascinating is that the sonic crack is louder, the further the bullet travels, so if you shoot a pig in a pen, the neighbours are less likely to hear it than say a 200m shot at a monkey.

Thanks, that's very helpful, and a good starting point.

Out of curiosity, what do you think would work better? large rifle primers or small rifle primers from palma brass?

I really don't know - no experience with palma cases.

The LRN bullet pushes into the lands.

If memory serves correct the trajectory was something like spot-on at 20m, 2" high at 40m, spot-on at 60m and 2" low at 70m.

Treeman has experience with this as well - he will probably chime in as soon as he sees that I have posted ... someone needs to check me up 😉 😉

Last things for now:
- Going close to and over the sound barrier has a negative effect on accuracy,
- Remember that subsonic ammo has very little shock effect, if any at all. It just pokes holes, hence accurate shot placement is very important.

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If you intending to kill things with the .308 sub, use the flattest, most metplat bullet you can, then the poking holes matter becomes tissue damaging tunnels.

Has anyone done research on using monolithic bullets for subsonic purposes?

A hard metal surface would make a sharp cutting edge?

I'm out of my lane here but I doubt copper or some other metal harder than higher end lead alloy (i.e. 'hardcast') would do better for the application.

I'm out of my lane here but I doubt copper or some other metal harder than higher end lead alloy (i.e. 'hardcast') would do better for the application.

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The mono metal in Impala form will work well in regard to wounding affect, but I question the ability to stabilize the long bullet using standard twist rifle barrels?

I shot their 130gr LWHV. Accuracy was good enough for head shots at 120m.

I shot their 130gr LWHV. Accuracy was good enough for head shots at 120m.

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At sub sonic ? ?

Tree, what did you shoot with on the farm the night you showed our fellow hunters that the other people behind us would not know that you were shooting?

This is the night you shot the dead tree by moonlight, just before Jansonville.

My old .308 Mauser and 160gr Frontier bullets at sub sonic. Yes, I recall, if you shot away direction from people 20 ft away they did not know you were shooting. I remember saying, " they will probably look up at the hits on the tree"

That statement stuck in my mind.

My old .308 Mauser and 160gr Frontier bullets at sub sonic. Yes, I recall, if you shot away direction from people 20 ft away they did not know you were shooting. I remember saying, " they will probably look up at the hits on the tree"

That statement stuck in my mind.

If the old Mauser stabilised them 160gr Frontiers, one should be able to stabilise 130gr as well?

Edit: my previous post didn't go through.

How much influence does bullet speed have on stabilisation? How does it work?

Those 130 gr mono's are loong ? At lower speeds I believe speed has a lot of influence, lot more sensitive to twist rate. That is why upping speed helps stabilize marginally unstable bullets.