Re: Problems Hornady 178 Superformance over presure
Here is some info from the Jan 2010 edition of American Rifleman. It's not for the 308 but is info on the Superformance Ammo:
"Using a SAAMI-standard 24" .243 Win barrel and an Oehler System 83 with Model 55 Infrared screens, Hornady's 95gr SST Light Magnum load attained 3159fps at 15', while producing an avg 57,600psi chamer pressure. With the same bullet, Superformance achieved 3175fps at 55,900psi. A competitor's load, also with a 95gr projectile, avg 3093fps at 55,600psi. Further testing revealed that Hornady's 80gr GMX reached 3397fps at 57,300psi, while a competitor's 80gr load avg'ed 60,000psi -- the SAAMI-listed MAP is 60,000psi -- to attain 3427fps. A single 85gr load hit 3270fps, but did so with a 55,900psi avg, SAAMI standard for an 80gr projectile is 3335fps, while a 95gr bullet is listed at 3060fps. The increase in velocity was obvious, as was the competition's proximity to the MAP with certain loads. Velocity gain occurred across the spectrum of loading with Superformance. Take the 300WM for example. With a 150gr GMX at 15' Superformance attained 3400fps with a 61,200psi avg, and a 180gr SST reached 3112fps at 59,600psi. In comparison, a competitor's 150gr projectile reached 3232fps at 57,700psi, while a different competitor achieved 3001fps with a 180gr bullet and a 61,500psi avg. Considering the SAAMI-listed 300WM MAP is 64,000psi, and SAAMI standard for said projectile weights are 3285fps and 2960fps, respectively, Superformance's velocity gains are readily apparent and significant. Pressure curves -- including Light Magnum's -- of the various 243 Win loads revealed what was felt from behind a range safety door: concussion. Superformance's was noticeably less than that of Light Magnum, as well as that of the majority of the competition, due to the progressive nature of the propellants. True to Emary's findings, trigger time also revealed noticeably less perceived recoil than with the other loads -- especially Light Magnum, but with other loads as well. This allows shooters to get better performance without significantly increased recoil."
It's a lot to read but does show that Superformance should be running at lower pressures. But also Hornady's listed FPS for the 178gr round is 2775fps out of a 24" barrel and you were getting an avg of 2935. Wonder if Hornady is having trouble with quality control???
