Originally Posted by eddybo
This occured shooting a load that is under book max. 42.4gr varget under a 168. I have people tell me all the time that if a load is within book max it is safe.
People that handload that think because their powder charge number matches the one on some book's page, that was worked up in another gun, with different brass, or other componts is safe don't really know what they're doing. The problem is that a good percentage of the reloading community has been duped in to believing that "never exceed max charges listed" means that if you don't you're safe. And without fail these people will, even if they agree somewhat with other's methods, fall back to "stick with tried and true book data and you can't go wrong." Yeah, you can! You're living proof! I use a different method to work up loads. I use my chronograph!
Here's an example of a max published load for 30-06: 165 Nosler Accubond, WLR Primer, Win Brass, 58grs H4350, COAL 3.340, 2867fps from a 24" bbl. ( I made this up by way of example...the powder charge/bullet wt combo are a long time tested load...you'll find it as a max load or within one grain in most loading manuals)
Ok I have RP brass, a different lot of H4350, and a 23.6" bbl. In my load work up I drop back 2-3 grains, load, and shoot, ane work up. I watch my chronograph and my brass. When I hit 57.5 grains, the chronograph says an average of 2860 for 5 shots. I'm at max for my gun with my components regardless of the fact that the book says I can add another half grain.
In fact, chances are I could do it safely, but why? The flip side of that is that if I hit 58grs, and I'm only at 2725fps, I'm going to add powder to get me up to @2850. In fact, though, in my gun 57.5grs produces max velocity, and to me that's when you've hit max, not based on some arbitrary "max charge"
in a book worked up in another gun.
Funny thing is I know a lot of loaders who would agree with stopping short of the max charge if you're getting max velocity, but somehow their brains can't compute going over a published max charge if you're under max velocity. These are the guys that typically refer to book data as "optimistic". It's not optimistic, it just wasn't worked up with your components in your gun. And by under velocity, I don't mean 20fps, I mean 100+ fps. If you're within 25fps of max velocity listed for a particular bullet/powder combo, then IME, you're there.
Then there's the whole concept of burn rate of powder vs velocity. The burn rate of powder, and it's relationship to case capacity, bore size, and bullet wt, affect how fast you can safely push it. For instance, you can't safely push a 180 in a 30-06 as fast with Varget as you can with R-22.
I don't know if you used a chronograph or not, but chances are good it would have told you that you were "hot" long before you worked up to the "hot load".
Finally, the heat you're shooting in, could be a real cause of this load being hot, when at 70F and under it might be just fine. Which is why I don't shoot this time of year!
And since I expect someone to read all that and ignore 99% of it and ask "why do you need to chase that extra 100fps?" Here's my answer: "Im not chasing anything extra, I'm not chasing anything at all. I'm simply looking to get what the data says I can safely acheive. IOW, I'm only trying to get up to the speed limit, I'm not trying exceed it and get away with it. Chasing "the extra 100fps" would be trying to get 2950fps when the book says 2850fps is produced with a max load."