That’s a great box of cartridges

According to the math, that bullet is 1.406" in length. It has a 550 grain weight so the Sharps nose profile got a lot of weight in a shorter length bullet compared to the Metford shape that Dan Theodore copied.

I think some were. My original long-range Borchardt has a 1-18" though. They were the last of the Creedmoor rifles built so it could have transitioned from1-20"  to 1-18" in that short period of time.

Yeah it seems a little heavy for the length.  BACO lists their .459" 555gr Creedmoor bullet as being 1.440" long.  I think they use 20:1 for their weight numbers.

Chris.

When a bullet is heavy for it's length, it will usually mean that the nose is shaped different and when you transfer weight forward on a bullet, it will need more twist to stay stabilized, because the center of gravity (CG) has moved forward.

That's one of the problems using the Don Miller formula. It will give the same answer for a wad cutter or a 8 caliber ogive.

You will have a lot better twist results, if you use the Geoffrey-Kolbe program. It solves for CG because you input the nose shape and for what happens at subsonic velocity's.

Regarding the Greenhill formula, it was derived for a 3 cal ogive artillery round, as I remember and although I haven't found at what velocity, I think it was ~1000. Before I had a computor, I used 135 as a constant, for a 4 cal ogive at 1400 fps and proved it out in 32 cal, at 200 yards.

Here is a example of the G-K output. Note the sub and transonic curve.