Hello LRH friends -- I've hit a bit of a load development head scratcher that I'm hoping folks here can help me out with.
I have a very accurate H1000 load worked up for my SSG custom .300 RUM -- stupid low ES, tiny groups, and all that good stuff... but let's face it, a pitcher that throws a 101 mph fastball is much more exciting than one that throws 86 mph
Based on advice from you folks, and especially Jon A's well documented success
with .300RUM/240SMK/US869, I'd thought I'd give US869 a whirl (note: CCI 250 primers).
I've had really good luck with the OCW method -- so I loaded 5 rounds each from 96 to 102 grains of US869 (and some fouling rounds) and hit the range.
I did the whole round robin thing over my chronograph. On the upside, I certainly got my fastball. 5-shot average of 2998 fps at 101 grains with no pressure signs, 3026 fps at 102 grains but the bolt was a bit sticky.
The 101 grain isn't too shabby, ES: 16, STDEV: 6.67 -- it grouped sub-MOA, and if my previous load development with this gun is any indication, I'd bet I could tweak the seating depth and get it to make itty bitty groups... if I could get it to always stay 60 degrees where I'm shooting.
So there's the rub: plotting both the average Y-axis POI's and the average velocities versus the powder charge, I get basically straight lines -- no apparent 'nodes' to be had. I've never really had that happen before, and I'm not sure what to do about it...
I could be happy with 3000fps and ES of 16 from the 101gr load, but from what I understand, this isn't the most temperature stable powder... That wouldn't make me so nervous if I could pick a charge in the middle of a big fat OCW node --- but in this case, a little "hotter" gets me pressure signs and an ES of 50+, and the 100gr load's ES/SD numbers are pretty crummy. I'd hate to burn more barrel only to develop a load that only works well on mild spring days.
I don't really know where to go from here --- given my awesome results with H1000 (save the lackluster velocity), I don't think I have a reloading technique problem (doing everything the same way in terms of prep/loading process). I could try a different primer, but I don't quite see how that would address this particular issue...
Am I making too much of my apparent lack of obvious OCW nodes? Assuming not... any ideas?
I'd hate to give up on the powder, as the velocities are definitely nice... that and I bought 8lbs of it (take what you can find these days!).
Your thoughts appreciated... thanks guys!