.357 sig with APS350?

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.357 sig with APS350?

Post by paulnick » 25 Apr 2021, 8:41 pm

Has anyone reloaded .357sig with APS350 powder 123gr Tigershark projectiles or any projectiles. APS350 only powder I can get. Used in a Sig p320 120mm.
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Re: .357 sig with APS350?

Post by Macross » 29 Apr 2021, 10:03 pm

APS350 is the fastest powder that ADI made. They dont have any load data for .357sig as i guess you have found. Load data that is in their most recent book is all AP70 which is equivalent of Alliant Unique. If i were trying to work up a .357sig load, I would be tracking down Unique as a starting point. I think APS350 may be too fast for what you need. Could be wrong and cant speak from actual testing.. just going off published data.
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Re: .357 sig with APS350?

Post by rc42 » 30 Apr 2021, 11:41 am

I'd suggest contacting ADI directly for advice, they are usually very responsive to customer queries.

APS350 would give lower projectile velocities and higher chamber pressures than AP70/Unique so would only be suitable for lighter loads, you could probably start with the bottom end of the 38 Super Auto load data for that projectile with APS350 and work up.
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Re: .357 sig with APS350?

Post by paulnick » 23 May 2021, 4:05 pm

Started some load development with APS350 357sig 123gr tigershark hollowpoint in sig p320. Action started functioning correctly at 4gr.
4gr 1024fps
4.3gr 1076fps
4.5gr 1095fps
4.8gr 1129fps
Above had no signs of pressure issues. Average fps over 5 shots. Didn't reload any above 4.8gr.
Factory measured 1379 fps
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Re: .357 sig with APS350?

Post by ob1 » 23 May 2021, 7:48 pm

Someone in Perth recently blew up their gun trying to get fast powders working in a case suited to slower powders. Some rounds worked OK, then boom. Just saying.
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Re: .357 sig with APS350?

Post by paulnick » 23 May 2021, 10:28 pm

The trouble I have in South Australia is APS350 is the only powder you can get for reloading pistol. Even that is near impossible to get now. I brought all the 357sig factory ammunition in Adelaide which consisted of a whole of 250rds ranging from $1 to $2 a round (which lasted half a morning). It would be nice to use the powders mentioned but at this stage there is no choice.
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Re: .357 sig with APS350?

Post by rc42 » 24 May 2021, 9:54 am

This is going to become more common as this shortage continues, we will likely all have to develop new loads using whatever powder is available.
357 Sig is a less common round so factory ammunition will run out first for that but other calibers will follow.

Your figures look reasonable but I'd suggest not trying to reach power factor with faster powder and keep the load down to what is needed for correct cycling.

I would also suggest sending an email to ADI with those figures and ask them for their comments, if nothing else it will highlight to them the difficulties that reloaders are starting to have in Australia.
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