I'll apologize for getting pretty detailed in my response below, and very long-winded. There's a lot to consider, but if you take the time to read all of this, I hope it'll illustrate at least ONE avenue that cripples this idea, without boiling the ocean for ALL avenues.

I'll run through all of the detail below, but the bottom line ends up at this:

__You won't gain as much as you're thinking in trajectory advantage. If I stretch out a .223remington with 50grn V-max to the same shape of a 75grn A-max but keep it at 50grns, I end up with 10" MORE DROP at 500yrds compared to a standard 50grn V-max AND it has the same drop (coincidentally) as a standard 75grn at 500yrds!!!__
If **longer bullets are better for ballistic stability**, why not just make bullets longer.

For instance, what would happen if a 55gr .223 bullet could be made longer (not actually stretched of course) but perhaps cast into a longer jacket with a lighter lead alloy. In theory, __you'd end up with the same weight but also a projectile with a better BC__.

The simplest answer here is that the bolded statement above is not correct - longer bullets are less "stable" than short bullets. Long bullets need more spin to stabilize than short bullet. BUT, your second statement, underlined above, is correct, but the advantage isn't there - which I'll discuss below.

Longer bullets - in general - have better aerodynamics, NOT better "ballistic stability."

In lock step with that, there are physical real world limitations that come into play, just a few of which I'd list below:

- Chamber throat length and bullet jump
- Magazine length
- Case capacity
- Bullet ogive length vs. bearing surface for rifling contact
- Barrel twist rate
- Barrel length and muzzle velocity
- Penetration will be decreased compared to its bullet form (lower SD for size

Discussing each of these topics could be equally long-winded posts, but the short version is that there's a LOT going on that can't be ignored when you talk about changing a bullet profile and density.

So let's do a little exploring down one of those rabbit holes: I shoot a lot of 50grn Hornady V-max's, and a lot of 75grn Hornady A-max's in 22caliber.

**What would happen if I took a 50grn V-max and stretched it out with an appropriate alloy density change to make it look like a 75grn A-max?**
I can look at it two ways - either I'm growing a V-max, or I'm lightening up an A-max. If I stretch the 50grn, that'd grow a 0.7770" bullet up to 1.1210" and change my BC from 0.242, upward - it would not be the same 0.435 BC as the 75grn V-max because that bullet doesn't have the same sectional density.

But that's easily calculated - the 75grn A-max has a BC of 0.435, with a sectional density of 0.214. Since BC = SD/i, where "i" is a form factor (not a drag coefficient, but related). For that particular bullet, if .435 = .214/i, then i = .214/.435, so the form factor for the SHAPE of the 75grn A-max is 0.492. It's easy to calculate from there what BC would be for the 50grn version of the same bullet shape: 0.224" 50grn bullet, SD = 0.142. 0.142/0.492 = 0.289

**SO - if I stretch a 50grn V-max out to be the same shape as a 75grn A-max, I'd only increase my ballistic coefficient from 0.242 to 0.289!!! Reminding, that's compared to the 75grn A-max of the SAME SHAPE of 0.435!!!**
And that doesn't even take into account that my stainless AR mags only let me fit 2.30" at max, and Hornady recommends 2.2390" COAL. Seated to the same length, there's 0.344" MORE BULLET taking up space in the case, meaning I have less powder capacity and/or higher chamber pressure. So when I run out that difference (indulge me the differential of a flat base vs. a boattail), that comes up to a lost capacity of 3 1/3grn of H2O.

So out of a ~30grn H2O case (.223rem), I'd give up 11% in powder capacity. Instead of packing 27.0grn of powder behind a 50grn V-max, now I'm losing almost 3grns of powder, and the 3,200fps that I'm able to hit today drops off to about 2,850-2,900fps, which was the starting load I used to develop my current V-max load - and not coincidentally - about the same as a MAX LOAD for the 75grn A-max.

Just for fun, run that through the Greenhill twist formula - a 50grn V-max at 0.7770" and using a generic 10.9 specific gravity at 3,200fps, I'll stabilize comfortably in a 1:12" barrel, whereas if I run that bullet out at 2,900fps at 1.121", now I need a 1:8" twist to stabilize it. That kinda kills anybody with a DPMS, Bushmaster, Rock River, Savage, Remington, Ruger Hawkeye (not American), and many other models that come with 1:9" or 1:12" barrels - especially if you start talking about a 16" AR carbine that would only get about 2,550-2600fps with such a bullet.

What does that mean at the range? Punch in the numbers for a 50grn bullet with a BC of .242 running 3,200fps against a 50grn bullet with a BC of 0.289 running 2,900fps... The standard V-max at 3200fps would have 8" LESS DROP than a slightly more aerodynamic "low density" 50grn bullet at 2,900fps, which is coincidentally the same exact drop I get for a 75grn Amax at 500yrds running 2650fps. I show 82" of total drop for the 50grn LONG bullet, 74" for the 50grn V-max, and 84" for the 75grn A-max.

So - quick recap - you stretch out a 50grn v-max to the same size as a 75grn A-max:

- I only gain very slight BC improvement 0.242 becomes 0.289
- I lose ~300fps due to powder capacity loss from deep seating long bullets
- I need a 1:8" or 1:7" barrel just to stabilize a 50grn bullet
- There's no difference in 500yrd total drop compared to a 75grn bullet, even though the 75grn bullet is running even slower (higher BC)
- I drop 10" MORE with the "more aerodynamic" low density 50grn bullet than a standard 50grn bullet, and the exact same drop as a heavier 75grn bullet at 500yrds.
- Bottom line -
**I did a lot of work and didn't get any advantage for my trajectory**