very well done ,pretty incredible really. Id love to see a pic of the 48 inch barrel mounted
Quote from: Scotchmo on December 22, 2022, 01:32:33 AMQuote from: rkr on December 22, 2022, 01:15:32 AMHave you considered 257388 bullets for the .257? They are usually very accurate and you gain in BC and energy while still able to use 14" twist.Yes. I have that mold and have tried them. Not quite as accurate as the 257420, but I might try them again.I had some accuracy problems when I first tried them, the reason was this:388-dimple by abbababbaccc, on FlickrThat's probe pushing a cavity in the bullet base as the longer bullet won't go deep enough in the leade in. After I lengthened the leade in they worked fine and gave me some 5-10 fpe extra. If they don't work for you I can buy the mold off you.
Quote from: rkr on December 22, 2022, 01:15:32 AMHave you considered 257388 bullets for the .257? They are usually very accurate and you gain in BC and energy while still able to use 14" twist.Yes. I have that mold and have tried them. Not quite as accurate as the 257420, but I might try them again.
Have you considered 257388 bullets for the .257? They are usually very accurate and you gain in BC and energy while still able to use 14" twist.
Scott shot a series with two bullets, allowing the pressure to drop between shots.... This gave us the opportunity to see what happens to the BC over a wide range of velocities (down to about 650 fps).... Here is a graph of the G1 Ballistics Coefficients for the Arsenal "Bowman" (257420 scaled up to 7mm) and the FN version of my latest Bob's Boattail....This is the first time I have seen graphs over a wide range of velocities comparing relatively similar slugs with and without a boattail (that is obviously working).... The Sectional Density of the 96 gr. Bowman is 0.17 and that of the 106 gr. Bob's Boattail is 0.19.... At an average velocity of 910 fps (about what you would see at 200 yards), the Bowman has a BC (G1) = 0.17, equalling the SD (FF = 1.00) while the Bob's Boattail has a BC (G1) = 0.23, 20% greater than the SD (FF = 0.83).... in other words about 17% less form drag.... The new boattail, with the smaller step at the rebate and less taper is obviously working.... Relative to the G1 drag model, both of these bullets (in fact most airgun slugs) work better than the G1 (pointed) drag model in the high subsonic.... That doesn't mean their drag is getting less above 900 fps, it just means it is keeping a larger percentage of its velocity than a G1 bullet would do.... Bob