Having used H335 with the Hornady 120 ELD Match, and using Hornady listed components (Hornady case and WSR primer), I have found the manual just about spot on. The only difference I used was the COL. Hornady lists 2.245", I used 2.200" as the bullet engages the lands at 2.230" in my barrel. I was looking for a .030" bullet jump initially. I really don't have any idea yet as to how much difference that extra .045" makes with pressures, but with my COL, 26.0 grs of H335 was the most consistent in the ladder, 2478.8 FPS AV with an ES of 29. Going to 26.5 grs increased the velocity by 56.8 fps (2535.6 FPS AV es 53) and 27.0 gr increased that another 91.4 fps (2627 FPS AV) and the ES went up to 86 from the average.
I have since tried Remington 7 1/2 primers as they have a thicker cup than the WSR, which had one central primer leak at 27.0 grs. Having shot thousands of .223 loads in service rifle, and having tested numerous primers with the same load with only a primer change, I felt confident this would not make too much difference. I found that most primers, in that caliber anyway, didn't change the velocity or the ES by more than a few FPS.
I was surprised with the Grendel however. A change to Remington 7 1/2 primer increased the velocity considerably, but he ES remained very close. Not a bad thing I guess, but still a surprise. One of my good loads in PPU brass shoots the 120 Hornady ELD Match, 26.0 gr H335, WSR, and COL of 2.200" at 2529.2 FPS AV, with an ES of 5 out of my 20" barrel. Exact same load with the exception of a change of primer to Remington 7 1/2, gives 2586.4 FPS AV with an ES of 20. A bit more ES than I expected, but much more velocity than expected, an increase of 57.2 FPS. It is still a very good load in my barrel.
Next up for my testing will be an increase in the COL. Seating to longer lengths without the bullet being in contact with the leade.
Hope this helps some. Just my experience.
I have since tried Remington 7 1/2 primers as they have a thicker cup than the WSR, which had one central primer leak at 27.0 grs. Having shot thousands of .223 loads in service rifle, and having tested numerous primers with the same load with only a primer change, I felt confident this would not make too much difference. I found that most primers, in that caliber anyway, didn't change the velocity or the ES by more than a few FPS.
I was surprised with the Grendel however. A change to Remington 7 1/2 primer increased the velocity considerably, but he ES remained very close. Not a bad thing I guess, but still a surprise. One of my good loads in PPU brass shoots the 120 Hornady ELD Match, 26.0 gr H335, WSR, and COL of 2.200" at 2529.2 FPS AV, with an ES of 5 out of my 20" barrel. Exact same load with the exception of a change of primer to Remington 7 1/2, gives 2586.4 FPS AV with an ES of 20. A bit more ES than I expected, but much more velocity than expected, an increase of 57.2 FPS. It is still a very good load in my barrel.
Next up for my testing will be an increase in the COL. Seating to longer lengths without the bullet being in contact with the leade.
Hope this helps some. Just my experience.