Where do you stand on Sectional Density?

[NoStepOnSnek]

I heard on a podcast the other day that sectional density doesn’t matter as much with modern bullets. In my mind a 300 gr 458 Win Mag should be substantially more effective than a 300 gr 375H&H, but SD says otherwise. However, the SD concept was developed during WW1 from what I understand, with no updates to account for improved bullets. How do yall feel about it?

 

[375Fox]

I’m not sure any of your answers are really correct. Sectional density isn’t a good way to compare different brands of bullets because different designs function differently. It is another way to compare different bullet weights of the same brand lead core bullet. I think I’d lean towards it matters but not as much as bullet design. Once a bullet mushrooms it has a very different sectional density. For monolithic bullets, I don’t think it has the same importance depending on the bullet.

I would not consider using a 300 gr 458 bullet over a 300 gr 375 bullet though. I’d expect very little penetration from a 300 gr lead core 458 after it mushroomed on dangerous game.

 

[BryceM]

Well, "good bullet" often means one with a high sectional density..... so your questions make a bit of a circular argument.

If you're comparing solids, the 300 gr .375 will almost surely penetrate better than a 300 gr .458 bullet. For most purposes, the .375 is probably better in this situation. A proper 500 gr solid in .458 is probably better than either of the 300 gr bullets if we're talking about a situation calling for penetration.

If you're comparing other types of bullets, the construction of the bullet matters more, but again, SD is one of the characteristics that makes good bullets good.

 

[Mark458]

I'm definitely on the side of sectional density does matter. Bullets are definitely better today than they used to be, but higher sectional density will still penetrate better when all other factors being equal. Heavier in the same caliber will penetrate better than a lighter version of the same bullet.

When you try comparing different calibers as you did then you are going to get very different results depending on multiple factors.

When it comes to dangerous game I believe going with higher sectional density will rarely let you down

 

[IvW]

SD is tops for DG ideal top performing SD is around .330 or slightly more

 

[DaddyFlip]

We beat this horse to death many moons ago. Sectional density is merely a calculation, not a metric; it is, however, made up of two metrics that do matter... diameter and weight. Sectional density doesn't care about the shape, construction, material, color or brand of the projectile. It is a boring mathematical ratio that doesn't matter. For a given bullet within a caliber, heavier penetrates more. Across calibers, smaller diameters of the same weight penetrate more. Maybe I should say it a different way; it's not that it doesn't matter, it's that it's not a factor. Diameter and weight are the factors.

SD is good for marketing bullets, though; especially smaller diameter ones.

 

[DaddyFlip]

@IvW gave me an idea how to better illustrate why SD doesn't matter (is not a factor). Consider the following Hornady projectiles - Same "ideal top performing SD for DG of .330"; which one are you choosing for your buffalo hunt? You didn't pick the 416 because of SD, you picked it for (1) energy; (2) diameter; (3) weight. SD never crossed your mind. Even if the 30cal bullet was the same DGX Bonded construction, you wouldn't choose it for your buff hunt because the SD was .330. Even if it were legal, you never considered your 300 H&H for buffalo. SD doesn't matter.

Now if you're choosing between 300-350-400-450 grain bullets for the 416, they will all do the job on buffalo. The heavier the weight, the higher the SD, but that's only a consequence of the weight increasing, not some magical significance of SD. (By the way, every 416 bullet of equal weight has the same SD, regardless of any other metric, making SD even less significant when considering which brand and type of bullet you want to use.)