MMACFIVE Report post Posted December 20, 2015 Like NRALIFER stated above I also started using HSP when it was released based upon its burn rate. In my experience it is very similar to H4831. I have loaded it in multiple cartridges: 300 Weatherby, 7mm STW, 280 rem, 270 win, 6.5x55, 25-06, and others. In the large cases it has given me the same velocities as H4831/rR22/IMR7828/IMR7797 etc. In some rifles I've got great velocities but poor groups. But boy does it ever meter good! In the 30-06 size cases it has done a little better. In a Rifles Inc. 270 with a 23" barrel 60gr of HSp will send a 129gr LRX out the tube at 3350fps....really. I backed it down to 58 1/2 gr and shoot 3200+fps and less than .5MOA groups with a rifle that weighs 6lb 8oz all loaded up with a VX3 4.5-14, full magazine of cartridges and a sling. I get 3150 fps with a Barnes 145g LRX in a 280 and could go higher. Look at the Hodgdon reloading sight as they are always adding HSP. They have it for the 280 rem now. For the most part I have been trying to switch to the temperature insensitive powders....I do dot know how well HSP is with respect to temperature extremes. Does anyone? Share this post Link to post Share on other sites
nralifer Report post Posted December 20, 2015 RONINFLAG you could develop your own load by seeing if for the 300 rsaum there are loads for H4831. Start with the lowest charge in grains but use superformance instead, then increase the charge by 1/2 grain intervals until you either get a velocity that is good for you or you get primer flattening or extractor marks on your brass. If that happens then back off one grain and call that the max. You an expect 100 to at most 200 fps more velocity than what is quoted in you'll load data for other powders. Share this post Link to post Share on other sites
nralifer Report post Posted December 20, 2015 Any powder at extreme heat in the sun will increase burn rate an pressures will rise because the gun itself will be hot. So I am careful to check any max load I developed in cooler weather. That said I have not seen a big effect Superformance to temps of 85 degrees and sunny. At that temp MVs increased about 50 fps. Sun was shining on the gun heating it up. Share this post Link to post Share on other sites
