CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.
Actually, there is no published load data for WC872 in 308. But given certain known and published parameters, "I was able to get there from here."
More than one on-line reloading supplier carries WC872 at prices starting as low as $39 for 8 pounds - that is under $4.90 a pound! Wideners carries brand new, never loaded WC872 at that price. WC872's specific application is 20mm Vulcan Cannon. AA8700 data can be used, and I found it to be spot on when using Lee's PPM and volumetric data, checked with a scale.
All loads were in once-fired, sized and trimmed WRA 68 brass, with CCI #34 primers.
Load data was adapted from here: http://www.castpics.net/LoadData/Sur...apages/308.htm
I understand that I am not allowed to post specific duplex loads data here, so I won't. Message me if you want specifics. Ambient Temp was 88 F.
First load tested was straight WC872 49 grains (moderately compressed) under 190 gr SP (blemished Hornadys I got from Midway). Five rounds all fired, somewhat shotgun boomish. Point of impact was 5" low at 50 yards in windy conditions (moving target). The point of these rounds was to identify a baseline for unburned powder and any residue. Yes, there was a trail of granules down the bore, but not what I would call sooty or messy.
Next, referencing the above link, I tested duplex loads. All remaining loads were with 175 grn FMJ. The link called for IMR 3031; I substituted 844, and tested 3 steps -0.5 grn., 0.0 grn delta, and +0.5 grn. All shot well with increasing accuracy (point of impact normalized by the last stage) with slightly less bore granules at each step. No signs of excess pressure.
Observations and speculation:
1. Barrel temp remained very manageable. Reverting to standard 844 loads, barrel heated up.
2. Accuracy? Too early to say, but I think it was predictable.
3. No ka-booms were experienced.
4. Seems like WC872 could be used to extend conventional rifle powders, more economically, and at cooler barrel temps. I plan further tests in this direction.