[Unclenick]

mnoirot64,

I just did some checking and several things seem to be confused here. First, the Nosler data you cited is for a 158 grain jacketed bullet in my copy of their manual (#6), and is not for a 125 grain lead bullet, as you seem to be shooting (a 125 grain RNFP is something I've only seen among lead Cowboy Action Shooting bullets). Understand that the heavier the bullet, the more inertial resistance it has to going down the bore, so if offers more resistance (Newton's equal and opposite reaction force) to being pushed down the tube. This makes it accelerate more slowly, giving the powder more time to build to higher pressure. For this reason, bullet weights are not interchangeable in reloading unless they are very close (say, 5 grains difference or less). Bottom line, no wonder your current load is too light.

Second, note that different manuals show different charge weights due to different loading components and philosophies. Components are not automatically interchangeable even when they are the same weight. The Speer manual load Nick cited is also for jacketed bullets like your Nosler data. Jacketed bullets are harder to start forward from the cartridge case and to push into the revolver forcing cone and bore than lead bullets are. Again, this means they have more resistance to give the powder an opportunity to build pressure against. It also gives them more chance of sticking in a barrel if the load squibs out, which likely accounts for the Speer DNR warning.

In general, take the smallest recommended starting load you find and work up in steps of about 2% of maximum or 0.2 grains (whichever is larger) while watching for pressure signs (especially tight or sticky fired case extraction in revolvers), leading, accuracy drop off, or other untoward issues. But the data should be for your bullet type.

In your particular instance, you are running at low pressure. Part of that is due to your low charge weight, part of it due likely due to using lead bullets that are too easy (for Accurate #5) to push through the bore. On top of that, you are making the bullet jump to the throat of a .357 Magnum chamber, which also gives the gas more opportunity to bleed a little pressure down and makes the bullet take longer to get to the forcing cone where there's some resistance for the powder to build pressure against. So, the powder is basically having trouble making gas fast enough to keep up with the bullet under these combined circumstances.

You are not alone in this, I think. I don't see any lead bullet loads for bullets weighing less than 148 grains in Accurate's own data nor does Lyman start showing it with lead until 155 grains. I infer a consensus that #5 is too slow to build pressure properly against lead bullets lighter than around 150 grains, though it can do it with jacketed bullets. Another factor is that lead bullets often are most accurate only when peak pressure is high enough to bump the bullet diameter up a little to hug the rifling. You need a faster powder with these light bullets to get you to that pressure threshold.

It would seem to be that the bottom line is that #5 is too slow for your application. Accurate #2 would be better, as would HP 38, 231, Bullseye, Clays, N310, Universal, 700X, Red Dot, and a few others. IMR Trail Boss would be excellent for the light loads you seem to be after. It will burn much cleaner, and there is data available for it and some of the others I mentioned at Hodgdon's site, behind a 125 gr. RNFP, specifically.