Power Pro 300-MP, anyone?

I got into .300 BLK towards the end of the last Great Component Shortage and considered W296/H110 to use with 125 gr bullet but learned 300MP to be another comparable option - https://www.thehighroad.org/index.p...-different-labels.797388/page-6#post-10806193

- Winchester W296/H110 and Alliant 300MP
- Winchester W296/H110 and Vectan Ba6 1/2
- Winchester W296/H110 and Vihtavuori N110

I have had good results with 300 MP for 22 Hornet.
I am still in the process of testing it for 44 magnum and so far I have not been disappointed.

I use it for all my magnum and even supermag revolver cartridges. It does not disappoint.

I remember that article.... Sounds like it might be worth a try in my 44 Magnum. Picked up a pound last year but haven't had time to get around to it yet. I've heard good things about in 44 mag's from others. Should get busy and try some with various bullets.

I picked up a pound to try in the .357 Magnum. Seemed close to W-296, and with an extra grain or two was able to beat the 296 by about 50 fps in a 6” GP-100. (Don’t be fooled by Alliant’s optimistic velocities listed in their loading data. They used a 10” test barrel). Not sure if it is worth it, unless you really want highest velocity possible as accuracy seemed comparable to W-296/H-110.

WrongHanded said:

I found a Brian Pierce article on this powder.

https://www.google.com/url?sa=t&sou...FjAHegQICRAB&usg=AOvVaw2qe-TXMIyLnrWpK-ooOecQ

It seems interesting, so I bought a pound to try. Anyone have good or bad experiences with it?

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Squibbed when loaded light in a 44 Mag.

I'd be interested in trying it out in 357 Max with some Swift A-frames

Awhile back I did a little testing with 3 different bullets in 357 cases.
Did head to head testing with 2400 VS H110 VS MP-300
I used firearms with 3"/4"/6"/8" & 10" bbl.'s.

In the 3" bbl the 2400 outperformed H110 & MP-300.
In the 4" bbl.'s The H110 & the MP-300 started to pull ahead
6" bbl.'s and longer bbl.'s the H110 & MP-300 outperformed the 2400
The H110 & MP-300 were pretty much even until the 10"bbl. The MP-300 was 40fps/50fps faster than the H110. I was getting 30fps/40fps faster velocities with 158gr bullets then what the alliant's website listed in my 10" bbl'd contender.

I do want to do a little testing with the MP-300 in a 10" bbl'd 44mag contender and several different cast/coated bullets. Just haven't found the time yet.

I picked up some 300-MP a couple years ago when I couldn't find any 2400. Last year I bought a Ruger 77/357, so I figured it was a good time as ever to start experimenting with 300. It is for sure a more stout load than 2400 in a revolver. I haven't chrony'd any of it yet. And I'm not sure if I will use any of it with cast, non-coated bullets.

kcofohio said:

I picked up some 300-MP a couple years ago when I couldn't find any 2400. Last year I bought a Ruger 77/357, so I figured it was a good time as ever to start experimenting with 300. It is for sure a more stout load than 2400 in a revolver. I haven't chrony'd any of it yet. And I'm not sure if I will use any of it with cast, non-coated bullets.

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I didn't find any data for use of 300-MP with lead bullets, so my attempt to interpolate a powder weight got me a squib.

RealGun said:

I didn't find any data for use of 300-MP with lead bullets, so my attempt to interpolate a powder weight got me a squib.

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Ouch! Okay, then I may just stick with 2400 when using cast. Thanks for the heads up.

I played with it in a 357 Redhawk 5.5 inches. At the higher velocities and 158 grain plus loads with stock grips, ouch. I think it would make a good hunting load powder.

No chronograph so no velocity data, but I am sure it was fast.

I'm told MP-300 is very similar to W296/H110, any truth to that? Does it generate as much of a fireball?

ArchAngelCD said:

I'm told MP-300 is very similar to W296/H110, any truth to that? Does it generate as much of a fireball?

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It is very similar to H-110/W296, albeit a tad slower burning. Similar fireball, too.
As for a previous post about a squib load, Alliant claims you can use standard small pistol primers, but in my opinion when stuffing 18+ gr of ball powder in a .357 Magnum case, common sense suggests a magnum primer to ensure complete consistent ignition. Starting lower, and working up carefully, of course.

2ndtimer said:

It is very similar to H-110/W296, albeit a tad slower burning. Similar fireball, too.
As for a previous post about a squib load, Alliant claims you can use standard small pistol primers, but in my opinion when stuffing 18+ gr of ball powder in a .357 Magnum case, common sense suggests a magnum primer to ensure complete consistent ignition. Starting lower, and working up carefully, of course.

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Thank you for the reply.

I completely agree about using a magnum primer for slow ball powders in magnum cartridges.

2ndtimer said:

It is very similar to H-110/W296, albeit a tad slower burning. Similar fireball, too.
As for a previous post about a squib load, Alliant claims you can use standard small pistol primers, but in my opinion when stuffing 18+ gr of ball powder in a .357 Magnum case, common sense suggests a magnum primer to ensure complete consistent ignition. Starting lower, and working up carefully, of course.

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No, it's really the same story as H110/W296, in that downloading should be discouraged, as is reloading without proven data.

RealGun said:

No, it's really the same story as H110/W296, in that downloading should be discouraged, as is reloading without proven data.

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From Alliant's website:
REDUCE RIFLE AND HANDGUN CHARGE WEIGHTS BY 10% TO ESTABLISH A STARTING LOAD.
https://www.alliantpowder.com/reloaders/default.aspx

If you check Hodgdon's website, you will find starting charges for the W296 loads also are reduced 10% from their published maximum loads.
http://www.hodgdonreloading.com/data/pistol

Winchester used to have warnings not to reduce 296 loads by more than 3%, but that was like 30 years ago. This is the distributor's current recommendation.

2ndtimer said:

From Alliant's website:
REDUCE RIFLE AND HANDGUN CHARGE WEIGHTS BY 10% TO ESTABLISH A STARTING LOAD.
https://www.alliantpowder.com/reloaders/default.aspx

If you check Hodgdon's website, you will find starting charges for the W296 loads also are reduced 10% from their published maximum loads.
http://www.hodgdonreloading.com/data/pistol

Winchester used to have warnings not to reduce 296 loads by more than 3%, but that was like 30 years ago. This is the distributor's current recommendation.

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But I do know what happened with 300-MP.

2ndtimer said:

From Alliant's website:
REDUCE RIFLE AND HANDGUN CHARGE WEIGHTS BY 10% TO ESTABLISH A STARTING LOAD.
https://www.alliantpowder.com/reloaders/default.aspx

If you check Hodgdon's website, you will find starting charges for the W296 loads also are reduced 10% from their published maximum loads.
http://www.hodgdonreloading.com/data/pistol

Winchester used to have warnings not to reduce 296 loads by more than 3%, but that was like 30 years ago. This is the distributor's current recommendation.

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And if that data is for jacketed bullets, where do you go for a starting charge for lead?

RealGun said:

And if that data is for jacketed bullets, where do you go for a starting charge for lead?

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You could either email Alliant, or, if you are an experienced handloader, you could extrapolate data from other sources for similar powder (like 296/H-110), and arrive at a slightly lower starting charge for MP-300 and carefully work up from there. Since lead bullets vary so much (mold design, alloy, sizing diameter, etc.), it is more challenging to provide absolute data. I guess they figure people who are experienced enough to cast their own bullets are experienced enough to carefully proceed in working up their own data with their particular bullet design, alloy and firearms.

I've recently become interested in 300MP for loads in my .357 carbine. Alliant's load data (10" barrel) shows over 1600 FPS which almost matches my velocities with 2400 out of my 18 1/2" carbine using a 158 grain JSP. I'll be obtaining a pound soon and test out some loads.

I worked up some 300 BO loads with it and I'm very impressed with it's performance with Nosler 110 grain Varmagedons, ( Blems from SPS ). Getting a little over 2400 fps and the accuracy at 100 yards out of a 16" barrel was outstanding. As usual what works in mine may not work in yours so work up your loads. 300 MP is the smallest grain powder I've ever used and I could only get it to meter without binding the internals on my Redding BR3 powder measure.

2ndtimer said:

You could either email Alliant, or, if you are an experienced handloader, you could extrapolate data from other sources for similar powder (like 296/H-110), and arrive at a slightly lower starting charge for MP-300 and carefully work up from there. Since lead bullets vary so much (mold design, alloy, sizing diameter, etc.), it is more challenging to provide absolute data. I guess they figure people who are experienced enough to cast their own bullets are experienced enough to carefully proceed in working up their own data with their particular bullet design, alloy and firearms.

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As a well enough qualified and careful reloader I still had a squib with 300-MP. You can't explain that away with little put downs. I know what my experience was, and you can argue with my conclusions.