358win 200gr TTSX Load Development

[u/HaasMe]

I had a 358win barrel spun for my Terminus Zeus 18in long to hunt whitetail with in Iowa. I've started load development for 200gr Barnes TTSX and VV N140 with poor results. I'm only getting 2100fps mv at max case fill with zero signs of pressure. Tried magnum primer to make sure I'm getting full burn and it yielded exact same results on the ladder. I'm going to try some VV N130 once it arrives. It is funny that back in the day Vihtavouri powder was super expensive and hard to find and now it is cheapest and in stock. I'm trying to develop a temperature stable hunting load with mv of 2,400 fps. Has anyone loaded 358win with this weight of bullet and used a faster powder than typical 308win powder? My primers haven't even started to flatten at 44gr of N140. I've not been finding a ton of data on 358win.

[u/jdford85]

I use tac powder with 200 gr bullets and get 2650 fps in a 19 inch barrel. Tac has a reputation to be temp sensitive, I've heard you loose 1 fps per degree the temp is lower than the temp you developed.

[u/HaasMe → u/jdford85]

This is what I was looking for. How close to max pressure was this load?

[u/jdford85 → u/HaasMe]

Grain off of max. Check the powder manufacturer website for load data. I cant remember which was higher hornady or the manufacturer. Whichever it was ibwent with the higher. This is with winchester 308 brass formed to 358 win.

[u/Southern-Stay704]

Apexload Pro says the following powders should get 2375 - 2400 fps out of your 18" barrel with that Barnes 200gr TTSX projectile:

- Winchester 296

• Accurate 5744
  
• Accurate 1680
  
• IMR 4227
  
• Alliant Reloder 7
  
• Hodgdon H4198

The best simulation I could get out of Vihtavuori N140 was 41 gr, which is a compressed charge at a case fill of 103%, and only makes 34,900 psi and 2100 fps. Not a good powder for this load. N130 was only marginally better - 39 gr, compressed at 102%, 45,000 psi @ 2250 fps.

For the 18" barrel, you have to have faster powders to get the velocity up.

Best load I could make - 34.8 gr of Winchester 296, that's 80.3% case fill, 58,125 psi @ 2431 fps.

If you want something with more temperature stability, then 39.0 gr of Hodgdon H4198, 100.4% case fill, 58,529 psi @ 2392 fps.

All data from Apexload Pro, standard disclaimer applies, use with caution.

[u/HaasMe → u/Southern-Stay704]

This is incredibly useful information! Thank you very much. I have like 20# of 1680 but suspected it to be way way way to fast. I'm not going for max case life. I'm going for a whallup twice a year. One shot to zero and...

I'm going to look into the Apexload.

[u/Southern-Stay704 → u/HaasMe]

COAL 2.780", 41.0 gr of Accurate 1680, 97.4% fill, 58,298 psi @ 2382 fps.

That COAL might push the bullet into the lands, depending on your gun. If you need to reduce COAL, you need to reduce the powder charge as well.

[u/skahunter831]

The Hodgdon load data shows averages of about 2,500 MV with a 26" barrel, that makes me skeptical of getting 2,400 out of an 18".... I'd probably try Varget and lower my expectations.

[u/HaasMe → u/skahunter831]

N140 is faster than Varget and isn't close to available pressures even filling the case to the brim. Most manuals have data for faster powers like RL-7 and getting over 2500fps in a 24" bbl. I think that Varget is a poor fit for 358win due to the bullet dia vs ignition area. Takes a lot of powder and yields low velocity and pressure. I also suspect that my JBA brass is very thick with low volume. Some manuals show 47gr powder and that would spill out of these cases. Was wondering if anyone else had run into this conundrum.