How High Is Too High? Is there a point of diminishing returns?

[Rockdoc173]

I'm attempting to use the OCW load development method for the first time and I'm also using a new projectile (for me anyway) in the Hornady ELDM 147. For H-4350 Hornady's data says the max powder charge should be 40.3 gr.

Prior to starting the OCW tests I decided to get real world max pressure data from my RPR that's chambered for the 6.5 Cr. cartridge so I reduced that 40.3 by ten percent, which gave me about 36gr, and started going up from there in half grain graduations. 40.3 came and went and when I stopped yesterday I was at 44gr. with no discernible over pressure signs. NONE! I've pretty much decided I won't add any more to that 44gr simply because it has to be beating the crap out of my throat, but my question is this: how much is too much? If I could go all the way to 52gr or 62gr or 72gr etc. would that be acceptable given there is an absence of excessive pressure? Or should I keep the actual max charge around the book value? Why?

Hornady put that 40.3gr load at 2600fps, I wonder what my 44gr load would be hitting in terms of velocity? For that reason the added power could be beneficial but something just seems off to me.

 

[Rockdoc173]

[No message]

 

[supercorndogs]

You are probably very close to max.

 

[redneckbmxer24]

A good general rule of thumb is to stay under 43gr with H4350 and heavies in a 6.5 creed to be safe. There's been plenty of cases where people went higher during development without pressure thinking they're good to go regardless of what the vast majority of shooters have experienced and then one day they see pressure. There's so many factors that come into play that can set you over the edge, and don't think for a second that a really hot day or ammo sitting in the sun for a few minutes or cooking in the chamber can't do it because H4350 "isn't temperature sensitive". It absolutely can have pressure signs in higher temperatures that is doesn't exhibit with a lower temp.

Aside from possibly having a high pressure event, you're going to be killing your brass. Hornady brass isn't know for holding a primer the longest, the higher pressure you run the more you're going to damage it.