Home Forums Reloading Big Game Rifles Magpro

Magpro is an excellent slow burn spherical powder that produces outstanding velocity in such cartridges as the 270 Winchester and the 280 Remington and 300 Win mag. These are the 3 cartridges that I have tried with Magpro so for. 24" barrel 300 win, 180 gr. TTSX 84 gr. 3154 FPS, the same load in a 29" barrel produced 3213 FPS.
In the 280 Remington 65.7 grains produced 3132 FPS

For the 280 I used 270 Winchester 130 load data for the TTSX since the two have nearly the same SD. I wanted to load the 280 to the same pressure as the 270 Winchester

What about Pressure spikes in change in temperature?

What about them? The 300 Win mag load is 1.5 grains under max according to Hogdon load data and Berretz ran Quick load and came up with 62,000 PSI which gives some leeway IMHO

Does your groups get larger in the summer months ? Do you test loads in the winter or summer ?

I'm doing it now, I'll shoot groups shortly
I'm giving what I've done so far.


Yes I answered your original question, you are now asking a different question.

Ok...LOL


Do you work up loads in the winter or summer ? Shouldn't have use the word test... that's what you're doing now. Work up from start to you grain a half from max is what I meant.

We are experiencing extremely hot temperatures now we have set records for most 100 degree days and the Governor has called a State Of Emergency because of the heat. But I don't leave my guns or ammunition in direct sun and stay out of the highest heat of the day.

It has simply been too hot to shoot groups. Maybe I'll be able to shoot some groups soon

Ok good enough, be safe guy !

Magpro was designed for the WSMs as I understand, and it does great in my 270 WSM, except for temperature stability. I find it to vary by about 1 FPS per degree and just a 30 degree temp change increased the velocity right out of the node on my best load and opened groups up double size. If you can shoot at the temp you tuned at though it's great in the 270 WSM. I abandoned it and am trying to work only with more temp stable powders, since I live and hunt in AZ but travel to MT every fall where it can be Zero or below.
Magnum is an more stable alternative. Trying StaBall HD now also.

Ramshot magnum. I bought some Big Game for my .30-06. Magpro for the 300 Weatherby, but thought about Retumbo being in the extreme line would be better.

I’m still using it in my 270 WSM and have been happy with it overall. I’ve shot groups in the 30’s (not that cold) and it seemed ok but haven’t tested it at colder temps - but sure that the instability would show up as things cooled off as it has for others. In moderate temps it sure is fast & accurate though.

It’s the first powder I ever used in my 270 WSM. I may have a lucky gun but I developed my loads in NC summer temps and then used those loads in the fall in NY and Idaho for elk. It was a laser with 130 Interbonds and just an impressive combo. I never have speed checked them in the 20-30’s but out to 400 it still shot on point.

It was around 3300 or better with those 130’s and man did it flatten deer. Loved that combo.