What load is that?
I'm asking because according to the Hornady manual #4, a max load for 55gr jacketed bullets is 21.1 grains, but Hornady manual #8 lists a maximum of 20.0. Neither edition of the Hornady manual lists pressures, but Hodgdon's manual #25 says 20.5 grains yields a pressure of 48,600 psi while Hodgdon's current on-line data says 20.4 grains produced 53,600 psi. I load a lot of .223 with 4198 and just wanted to know where your maximum loads fell with respect to the various published "maximums".
The load I use: 21.5 gr of IMR4198 is listed as max with a 55gr FMJbt in Lyman's 45th, and Lees Modern Reloading, as well as the "real world, in my rifle" data I inherited from my dad.
I haven't had any problems with this load cycling, or with pressure signs, in either a 20" rifle, or 16" carbine (AR)
Primers flatten a bit, but ...meh. It is slightly more accurate in the rifle than the carbine.
So I treat it as a "max" load. However;
In my Speer #8 & #10, max is listed at 22.0 (both of these have some HOT hot loads in them)
And on the other end,
In Hornadys 7th edition, max is listed at 20.0. I've found this book to be full of powder puffs (relatively speaking).
When I refer to published data, I tend to throw out the highs and lows, average what's left, drop down .5-1.0 grains, and start from there to work up. That way, I shouldn't blow anything up, and it won't take me a week to run through test loads. (10-20 rounds each, in .2gr increments can take a while)
Because of the extreme variance found within the published manuals, it's good to have as much data as you can get your hands on to work with- said Captain Obvious
For reason I can't quite put my finger on, I like IMR3031 in the AR a little better.