Which Somchem for .375H&H, 20" barrel

[Boela]

I am a complete novice when it comes to reloading and am I hoping that a reloading enthusiast will be willing to help me regarding Somchem powders...... @IvW, @Dewald, @Gert Odendaal....... @anyone else willing to help?

I need to reload for said calibre and after numerous phone calls across South Africa, I came to the short answer from multiple dealers that S335 is either discontinued or will it not be in stock for the foreseable future...?
I have no means to verify this, nor the means to double check if this is indeed the case.

I have a cracking S335 load using 300gr Peregrine VRG3 bullets. I now need to make the decision if I am going to try and source S335 from some mysterious source, or am I going to switch to a more readily available powder i.e. S341 or S355 ?
S341 being granule / spherical powder and S355 extruded (both combusting at medium speed)

I hereby ask if some well informed individual would mind explaining the pro's and con's vs the different powders? What would you recommend me to use - S341 or S355?

 

[bruce moulds]

boela,
355 and 341 look to be a bit slower burning than 335
341 looks to be a tiny bit slower than355, which looks about the same burning rate as varget.
there seems to be one slower again, 365 which looks to be burning rate similar to h4350.
h4350 has given good velocities in 375 with 270 to 300 gn bullets.
it might depend on the density of the powder how much you can get in the case.
bruce.

 

[Boela]

Thank you for the feedback Bruce,
I would be reluctant to use the S365 in order to avoid potential compressed loads- a quick look in the manual also did not show any recommendations for it.

If we had to cut the burn rate out of the equation, what is the reason for the difference between the "shapes" of the powders? (Granule vs Extruded) Surely there should be a reason for it? Or am I now simply concerned about nothing?

We do have Vihtavuori powder available, but it is quite expensive and not that readily available. Any views on that?

 

[IvW]

S341 or S335 or even S355. Short barrel would like the faster burning powder.

 

[IvW]

S355 had a few bad burn efficiency batches.

 

[Boela]

Thank you IvW, looks like the next step will be to start with load development from scratch since no real pro' or con's were highlighted regarding the physical differences.
I appreciate everyone's input!

 

[Dewald]

S341. Your local shop has. Otherwise IMR4895. Safari has.

I’ll call you tomorrow. Work up to the same velocity over the chrony and fine tune further.

 

[Alchemist]

S355 will produce a less than 100 % powder burn as it is to slow for the 20” barrel. I have a 26” barrel and even this produce a less than 100 % burn. Problem is that this gives inconsistand groupings.
I would tend to agree with Dewald and try S341 if S335 is a problem.

 

[Boela]

Thank you Alchemist, Dewald and I had a discussion over the phone and it was decided to go with S341 - just as you are suggesting.
Thank you for your input, it is appreciated.

 

[IvW]

What load did you end up with?

 

[Garth5055]

What grain S335 are you loading for a 300 grain bullet on a 375H&H

 

[IvW]

What 300gr bullet are you referring to?
You get bullets and you get bullets.....
What rifle is it?

 

[Garth5055]

Bruno Deluxe 375H&H with pop 300.

 

[Garth5055]

pop

PMP

 

[Garth5055]

S355 will produce a less than 100 % powder burn as it is to slow for the 20” barrel. I have a 26” barrel and even this produce a less than 100 % burn. Problem is that this gives inconsistand groupings.
I would tend to agree with Dewald and try S341 if S335 is a problem.

What

S355 will produce a less than 100 % powder burn as it is to slow for the 20” barrel. I have a 26” barrel and even this produce a less than 100 % burn. Problem is that this gives inconsistand groupings.
I would tend to agree with Dewald and try S341 if S335 is a problem.

What load grains did you find best with a 300grain PMP

 

[IvW]

PMP is a real bad bullet for 375 H&H I woul rather use Rhino.

Here is the recommended loads from Somchem

 

[Garth5055]

PMP is a real bad bullet for 375 H&H I woul rather use Rhino.

Here is the recommended loads from SomchemView attachment 399740

Thank you.

 

[Daga Boy]

Rhino bullets are outstanding

 

[Daga Boy]

BTW, I would be really intrigued to hear the outcome of this experiment. I suspect the results may be less than fantastic regardless of propellant choice given the design of the cartridge and the barrel length , which is very short for this calibre , but would be interested to see.