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Author Topic: .30 cal. 68 gr. BBTs  (Read 368 times)

rsterne

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.30 cal. 68 gr. BBTs
« on: January 22, 2017, 06:03:24 PM »
I had a chance to cast some of the new .30 cal BBTs today.... I used 2% tin and cast at about 800*F.... The moulds for this bullet are available in two sizes, 0.300" and 0.303" at the back of the nose, with the driving band 0.002" larger than that.... The mould I have is the smaller of the two diameters, and cast at 0.301" at the back of the nose and 0.304" at the driving band using this alloy.... I purchased the RG4 mould, which is a 4-cavity with HollowPoint pins that are a loose, sliding fit in plates mounted on the bottom of the mould.... The RG moulds are available in 2 or 4 cavity, and come with HP pins, a "cup point" which is a shallow cone, and a flat pin that allows you to cast FN solids, all from the same mould.... Here are the spare pins that are not installed in my moulds at present.... all 3 sets came with the mould....



I installed two HP pins and two FN pins, and they are very easy to change.... I had to adjust the height very slightly, which is done by carefully bending the plates with a small crescent wrench.... and I set the FN pins a couple of thou too low, so the nose actually has a slight bump instead of being perfectly flat.... This is not an issue, but it probably increased the weight a couple of tenths of a grain.... My solids weighed 67.2 gr. and the HPs weighed 61.5 gr.... Here is what I produced this afternoon.... about 400 good bullets out of 500 cast.... approx. 200 each FN and HP....



and here is what the bullets look like close up.... The bullets on the very ends are "rejects", I'll talk about why below....



The pins can move vertically in the mould, and must be settled until they are right on the plate they sit on before casting.... If not, they can sit too high, and cause the rejects shown in the ends of the photo above.... These bullets weigh about 1 gr. less, and of course will vary in weight, depending on how much too high the pin is sitting when you cast the bullets.... There are instructions on the NOE website about how to cast with the RG moulds, and there is definitely a technique to learn.... My rejects were nearly all in the first half of my casting session.... Once I found a system that worked, I had very little trouble producing consistently good bullets....  My technique for "settling" the pins was after dropping the bullets, I closed the mould within about 1/2" and then very gently tapped the outside back corner of the mould with my "sprue plate mallet" (a heavy hardwood dowel) while holding the moulds on a slight angle so that the pins sat in place in the half of the mould they are attached to.... The vibrations from the tapping settled the pins down onto the plates they are mounted in.... You don't need to tap hard, and in fact if you tap quite gently and rapidly about a half dozen times, you can even hear the pins ringing as they settle into place.... You then close mold and cast the next set.... NOE recommend you tap the hinge pin of the casting handles, but I found that awkward and for me it didn't work as well....



The photo above shows where I tap my mould.... but I have it nearly closed when I am doing that (it is wide open only for the photo).... It doesn't show well in the photo, but the mould is rotated away from you a bit, about 30* from vertical, while tapping, so that the pins are laying in place in the grooves in the rear part of the mould, and the tapping rattles them down into place against the slotted bottom plates.... Do NOT hit the mould hard, you just need to rattle it to allow gravity to seat the pins.... a half dozen gentle taps works better than hitting it too hard.... Once you get the knack of it, the RG series moulds work perfectly....

Bob


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Re: .30 cal. 68 gr. BBTs
« Reply #1 on: November 04, 2017, 04:42:42 PM »
Any news on accuracy with these slugs?