.357 Magnum with 158 gr JSP and HP38 powder


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devils4ever
July 16, 2014, 07:36 PM
Hi all,

First post.

I've been reloading for a while for both rifle and pistol, but I noticed some large discrepancies in loads for the .357 magnum. I use mostly 158 gr JSP or JHP bullets.

For HP38 powder, my manual shows a range of 3.4 gr to 5.4 gr. These loads don't seem particularly hot.

So, I did some quick searches online and I see loads of 6.2 gr to 6.9 gr. What gives? Has this powder changed over the years? I've had my can for quite a while.

Thanks.

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ArchAngelCD
July 16, 2014, 08:14 PM
Hello and welcome to the forum.

Differences in load data are the result on a lot of different causes. Different powder lot numbers, different testing equipment, different bullets, different brass, different OAL and seating depth, different temperature and humidity on testing day and probably a lot more will cause differences in load data. This is why they supply a starting and max charge weight for their test rounds and not necessarily your ammo.

In general I go to the powder manufacturer/distributor first, them the bullet manufacturer's data and then a good load manual or three. Hodgdon has .357 Magnum load data on their site for HP-38/W231 and a 158gr jacketed bullet. They list a charge range of 6.2gr to 6.9gr HP-38/W231 like you said. Who supplied that light load data you listed above? Are you sure that wasn't data for a lead bullet? Hodgdon list a charge range of 3.4gr to 5.0gr with a 158gr LSWC bullet which seems to match your data above.

devils4ever
July 16, 2014, 09:32 PM
I have the Speer and Sierra reloading manuals. Neither one lists HP38, but I have the 357 Magnum Loadbook which lists all bullet manufacturers and powder manufacturers. In it, it shows 3.4 to 5.4 gr for a 158 gr JSP. See attachment. It lists lead bullets at 3.4 to 3.9 gr. But, now online (handloads.com and reloadammo.com), I see loads of 6.2 to 6.9 gr. So, did the powder change? Or, did Hodgden change their minds? :rolleyes:

I want to be safe, but these loads seem light. I probably bought the powder 10 years ago.

ArchAngelCD
July 16, 2014, 10:13 PM
"Neither one lists HP38"

Just in case you didn't know, W231 and HP-38 are the SAME EXACT POWDER. You can use any current W231 data with HP-38...

Those single caliber load books are handy but you have no idea how old or where the data was copied from. I suggest using the data on the Hodgdon load data site. It has been tested and it's current. http://www.hodgdonreloading.com/data/pistol

devils4ever
July 17, 2014, 07:44 AM
"Neither one lists HP38"

Just in case you didn't know, W231 and HP-38 are the SAME EXACT POWDER. You can use any current W231 data with HP-38...

Those single caliber load books are handy but you have no idea how old or where the data was copied from. I suggest using the data on the Hodgdon load data site. It has been tested and it's current. http://www.hodgdonreloading.com/data/pistol
Thanks for the info on HP38 and Win231. I just recently learned that.

Yeah, my Loadbook is from 1993. Maybe, it's a little out of date. Back when I started reloading, Al Gore didn't invent the Internet yet. I'll have to start using the net more for load data. I'm just hoping that the powder hasn't changed during this time.

BTW, what's an accurate powder for 357 magnum? At the time, HP38 was all the store had in stock. It looks like pistol powder is impossible to get anyway these days.

ArchAngelCD
July 17, 2014, 12:14 PM
BTW, what's an accurate powder for 357 magnum? At the time, HP38 was all the store had in stock. It looks like pistol powder is impossible to get anyway these days.
My 3 favorite powders for loading handgun cartridges are W231(HP-38), W540(HS-6) and W296(H110). You can and I have used all 3 for the .357 Magnum for different loads.

With HP-38 you can actually develop some high velocities and for me, accuracy. Of course being a fast powder it will top out in velocity and pressure long before the slower powders. With a 158gr XTP you can probably generate ~1100 fps from a 4" barrel. (maybe) With lead bullets I use a lot of HS-6. I find it to be very accurate with 158gr LSWC bullets in the .357 Magnum. HS-6 works just as well with jacketed bullets too. For top end loads there is nothing like W296/H110 but be careful with that powder, it works best at the very top end of the pressure curve. It's also highly recommended you use a Magnum primer with it.

Top powders for full power .357 Magnums include: W296/H110, 2400, AA#9, Power Pro 300-MP, Accurate 4100 and Enforcer. Of course those are the full power powders but you can use the medium burn powders like HS-6, Blue Dot, Power Pistol, AA#7, Unique and Universal too. You will lose some velocity but they can be used and will produce accurate ammo.

Having only HP-38 isn't all that bad. You can load most handgun cartridge with it and it's known to produce accurate ammo. It's probably my favorite powder followed by HS-6. There are reloaders all over the country hunting for a jar of W231/HP-38 without success. It seems you got very lucky!!

2bfree
July 17, 2014, 01:33 PM
I load a 158gr RNFP using HP38. 6.4 gr is as hot as I like as I just start getting some flash out of my 6 1/2 inch Ruger Blackhawk. No flash from 6.2. Very accurate.

devils4ever
July 18, 2014, 07:33 AM
Lucky? No. Like I mentioned, I've had the HP38 for many years. I shoot 10X as much rifle rounds (223, 22LR, and 30-06) as 357. I guess this is a good thing these days since buying pistol powder is near impossible.

2bfree, thanks for your load. I'll try it out on my next batch.

devils4ever
August 30, 2014, 09:21 AM
I load a 158gr RNFP using HP38. 6.4 gr is as hot as I like as I just start getting some flash out of my 6 1/2 inch Ruger Blackhawk. No flash from 6.2. Very accurate.
I used 6.2 gr and they seemed much better (hotter!). Better muzzle flash and more recoil.

Unfortunately, I'm just about out of HP38. :( Can't seem to find any pistol powder locally or on the net. I guess I'll have to buy commercial ammo (gasp!) until the madness is over.

gamestalker
August 31, 2014, 05:40 PM
The lower charge load of 3.4 gr. - 5.0 gr. HP38 is for cast LSWC, not jacketed, which is what you are using.

The jacketed data that would apply to the JSP you are using, is in fact 6.2 gr. - 6.9 gr..

Jacketed bullets create more friction, therefore they need more pressure to push them through the barrel, thus the difference in data tables.

GS

Rule3
September 1, 2014, 02:03 AM
Bottom line, HP38 although a great all around powder is not a true MAGNUM powder.

For full magnums you want a slower powder like 2400, H110/W296 (also the same) There are others. 2400 is great if you can find it.

You will find a major difference in those loads!;)

gamestalker
September 1, 2014, 03:13 PM
Absolutely, just like Rule3 said, for magnum full house you need a much slower burning powder for this. I'm really partial to H110 / 296, but there are some very good options like Rule3 mentioned.

I'm need to give that Power Pro 300MP a try, if I'm correct, but anyway I've heard some good stuff about it.

GS

GaryL
September 1, 2014, 05:03 PM
Welcome to the board. Looks like your question was answered in short order.

If you enjoyed reading about ".357 Magnum with 158 gr JSP and HP38 powder" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!