280AI recipe Peterson Brass 160gr AB w/H4831sc

[xebadir]

Looking for some advice as I work on this load - specifically using Peterson 280AI brass.

Planned load is a 160 GR AB, with H4831SC with CCI200 primers as I've heard H4831SC is a good choice (and is the most accurate in the Nosler manual), however, in reviewing water capacities for the two casings, I note that the Nosler case holds around 3 grains (74 vs 70.8) more, which means to follow their load would put me well into dangerous pressure range. Looking around it seems the general theory is to start around the equivalent percentage on a ladder, so in this case, somewhere around 5% lower than the Nosler load from Min to Max (55-59 gr). Looking at the matching Hodgon data seems like its a little lower 54-57.5, but no insights there on case volume. Plugging into GRT 5% off the Nosler load seems to be acceptable with the Peterson case, so my question is, does anyone have a baseline for this combination, or a favored load using this bullet and case? Plan to carefully work my way up once I have a starting point.

 

[mevertsen]

This is why you start 10 percent low and work up.

 

[xebadir]

Ok thats reasonable - but is that 10% low on the modified case volume, or 10% off the Nosler load, or 10% of the Hodgdon number given the brass differential? It seems like Hodgdon generally runs on the conservative side though they don't state their brass capacity (based on the pressure numbers I'd say its lower than Nosler). A 5% drop off the Nosler minimum would yield approximately that (53.1 gr), and my thought was to start about 52.2gr and roll up from there to a max no further than about 56gr and watch closely for pressure as I move through (which will be harder to spot given the cartridge).

 

[mevertsen]

Pick a book. I would suggest Nosler, since that the bullet you are using, drop 10 percent from max and work up.

With 4831, I would be doing 1 grain increments 1 or 2 shots each to find pressure.

Then back off and fine tune.

You are likely going to be very full anyway, if you can even hit pressure with that powder.

 

[marksjeep]

Hodgdon is using Nosler brass for their published 280AI 160 AB load.

 

[xebadir]

Hodgdon is using Nosler brass for their published 280AI 160 AB load.

View attachment 379273

Damn it, missed that on my screen. Thanks, useful info.

 

[Arcola]

I’ll second the -10% approach. You won’t burn up much powder starting low and working up. I work up in half grains, myself. I would be blown away if you can hit pressure with 4831 in Peterson brass unless you’re compressing significantly. I switched from Nosler to Peterson a couple years ago and was able to maintain charge weight with RL23, but I’m compressed in the Peterson and was not in the Nosler.

 

[Wind Gypsy]

Lets be honest, hardly anyone builds a 280AI to run min load velocities. You dont want to be below 55 gr. Personally, i'd do a single shot ladder from 55-59 at 0.5-1 grain increments and watch velocity/pressure signs and go from there. If velocities significantly exceed what all the books say is max, you're probably over pressure whether you have signs or not.

 

[EastTNHunter]

I wouldn’t be surprised to have to go over max with H4831SC, but not saying that you will have to either. I have some standard H4831 and some of the SC. I with a 140gr bullet in my 270 Win I use 58gr of H4831 and 60gr of H4831SC to get the same velocity. No pressure signs in either