30 XCB with LvR in 30x60 XCB
Friday I also tested the WQ'#2 alloy XCB over LeveRevolution powder in Dawn. I chose not to use a Dacron filler in the 30x60 like I used with success in the Palma rifle in .308W with 14" twist. It proved to be a bad choice as the internals sucked with the 5 test loads. I loaded 46 to 50 gr LvR in 1 gr increments to test. Even at 50 gr there was sufficient air space in the case for a Dacron filler. The velocity ES ranged from 58 to 116 fps and the psi ES ranged from 4,700 psi to 8,800 psi.....neither very good.
Accuracy with the first load of 46 gr wasn't all that bad at 1.85" for the 10 shots at 100 yards. After that the groups got larger and larger with some serious flyers.......as I mentioned in the previous post I'm finding that 2850 - 2950 fps seems to be the upper limit for #2 alloy. The problem I encounter here around between 2928 fps and 2972 fps was the bullets were shedding the GCs very quickly, like before the bullet got to the screens! I've had bullets occasionally shed a GC but the 47 - 50 gr loads did it quite consistently. If you look closely you can even see some of the stability indicators in the not round holes of the more extreme flyers.
The 46 gr load ran 2873 fps at 44,200 psi, 1.85".
The 47 gr load ran 2928 fps at 45,500 psi, 3.75".
The 48 gr load ran 2972 fps at 47,300 psi, 5.4".
The 49 gr load ran 3025 fps at 51,000 psi, 5.3".
The 50 gr load ran 3103 fps at 56,700 psi, 8.4".
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Worse part of the bullets shedding the GCs was it really tore up the screens. Those little 3 gr GCs at 2900 - 3100 fps pack a wallop! Was the right flyer in the 49 gr load that took out the right diffuser. That's when I checked the screens and found all the damage. I'll be casting some 30 XCBs out of linotype and WQing them for further testing. Their BHN should be in the 28 - 30 range and perhaps the GC shedding will cease with the stronger alloy? If you note the 50 gr group at 3103 fps 4 of the shots that went to point of aim appear not to have shed their GCs. That is a sub 2 moa group and is what I'm shooting for (pun intended:lovebooli)
Larry Gibson
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