I agree, nice picture.... How would you make it, and at what cost?.... I'll take a guess at the BC at about 0.115, the same as the SD.... Virtually no expansion at airgun velocities.... A lead roundball in 20 ga. would weigh 349 gr. with BC(G1) of ~0.082... In cast linotype, a 20 ga. roundball would be about 318 gr. with BC(G1) of ~0.075...Sighted at 50 yards, the 309 gr. boattail starting at 950 fps (619 FPE), PBR (4") = 84 yds, would be about 9.35" low at 100 yards, retained energy 478 FPE.... Using the same FPE of 619, same 50 yd. zero, the lead roundball would be going 894 fps at the muzzle, PBR(4") of 79 yards, and would be about 11.19" low at 100, retained energy 448 FPE.... while the linotype roundball would have a MV of 937, PBR (4") of 81 yds, and be about 10.39" low at 100 yards, retained energy 427 FPE.... I doubt the deer would know the difference between 427 FPE and 478.... Just putting things in perspective.... cost and complication vs. available and cheap.... Bob
Yep, you solved that.... My question would be is building that special bullet worth the cost and difficulty.... For me, no, for you, maybe it is.... …. That's the cool thing about airguns…. If you can dream it, you can pretty much build it.... Bob
Copper doesn't work in airguns. Not enough power to get it going
And then there is the fact that aluminum oxidizes on the surface, its not thick by much but its hard as nails.I would advise against puting aluminum bullets in any barrel that costs money. If you could coat that aluminum bullet with thin lead then that might be worth trying.Marko