Airgun Slug Expansion for Hunting - Contributing Factors and How to Achieve It

Now once they make contact with the animal and they do weigh the same, I think the author is now focused on how much one will bleed off energy than the other. But we could really be splitting hairs here. Not concerning the laws of physics, there could be a very definitive difference. On an animal? Probably not.

Ezana4CE said:

@Vetmx Weight? Since density was already discussed, I figured that weight was understood in saying that the softer lead projectiles of the same size would weigh more. Are you suggesting that he should have specified a particular weight in his hypothetical?

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Like I said in post #21, we could be splitting hairs. Especially with airguns. Our energy windows are very small. We focus on accuracy most because in the reality of killing, it’s all we have in our favor. The guy who is punching lungs with his big bore is not going to experience some kind of revaluation if he discovers a slug that expands a little more.

Ezana4CE said:

If someone can help me better understand what’s written here I would appreciated it. It is obvious that the reference here to bullet hardness correlated to the desire or necessity to increase the bullet’s melting point due to the temperature within the barrel relative to the charge of the cartridge. Aside from that, the premise communicates that pure lead is denser, will vary more energy, and this penatrate deeper if expansion is controlled. This is my understanding.
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Now if I understand this correctly, I have questions on expansion of soft-lead hollow-point slugs. In my limited experience with soft-lead airgun slugs, the penetration is there. It’s the expansion that I’m questioning and curious about because I have not been able to recover a slug that passed through an animal.

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I think the point being in powder burners the cast slugs expand and deform from the velocity ...With more speed they need harder lead for less expansion and also harder lead takes more velocity before leading. My 2cents

And tagging onto what RM.510 said. When we try to take too much from the powder burning side of projectile sending, we can get spun. I’ve found that a lot of stuff with airguns and bullets is a clean slate. What works for them just doesn’t work for us.

Ezana4CE said:

@RM.510bigbore Interesting. I thought the deformation was from the heat and pressure produced by the ignition of powder. Either way, it’s not something we should be concerned with shooting sub-sonic big bores.

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Yes the higher pressure and hot gas melt lead...The higher velocity you go the harder lead stays together. It's pretty simple. So highest velocity with cast is hard lead powder coated or high tech with gas check. The gas check is copper and keep s hot gas off lead cast slug. So for airgun s usually pure soft lead best.. You can shoot harder lead through airgun s too.......but it better be sized correctly for your bore...so if you wanna shoot through concrete or.old.cars with a big bore hard lead penetrates and doesn't expand at 1000 fps or below. Castbollits.com has taught me a ton..

RM.510bigbore said:

If you wanna shoot through concrete or old cars with a big bore, hard lead penetrates and doesn't expand at 1000 fps or below.

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Yes, I wanna do THAT!!
Sounds great, shooting old cars and junk!
Especially, since in my neck of the woods the lawgivers frown upon airguns shooting anything bigger than bunnies, so no BigBore-BigGame hunting....


One detail I remember from Bob Sterne's posts: Just like there is a BC or drag number for a projectile going through air — so is there a type of "flesh BC" — the drag or slipperiness of a projectile going through flesh.

So, if you are afraid you might not get enough penetration — make sure you have a high BC projectile.

But even if you have a semi-wadcutter shape with a pretty bad BC — if it's one of those monster slugs weighing "half a ton" and if your're slinging it at 900fps — then that might not make a difference:
The semi-WC is just going to push through flesh due to it's extremely high energy (momentum).

Matthias

Ezana4CE said:

@JungleShooter I’ll take the soft dense lead. Do you have a link to where Bob Sterne wrote about the “flesh BC?”

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Here's one mentioning:

➧ specifically post #34


Matthias

JungleShooter said:

Yes, I wanna do THAT!!
Sounds great, shooting old cars and junk!
Especially, since in my neck of the woods the lawgivers frown upon airguns shooting anything bigger than bunnies, so no BigBore-BigGame hunting....


One detail I remember from Bob Sterne's posts: Just like there is a BC or drag number for a projectile going through air — so is there a type of "flesh BC" — the drag or slipperiness of a projectile going through flesh.

So, if you are afraid you might not get enough penetration — make sure you have a high BC projectile.

But even if you have a semi-wadcutter shape with a pretty bad BC — if it's one of those monster slugs weighing "half a ton" and if your're slinging it at 900fps — then that might not make a difference:
The semi-WC is just going to push through flesh due to it's extremely high energy (momentum).

Matthias

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Buy a .510 I just cast a real lot of hard cast from wheel weights there powder coated silver...650 yr Sp BT .5 B.C .These kick. I found the wheel weights horded in garage form 80-90s.. New wheel weights are zinc To my surprise the hard lead out shoots soft lead in my Texan..Its more due to diameter.. Hard lead lighter than pure lead too.... I only used the hard wheel weight lead because I got a large quantity free..I didn't think they shoot in my big bore...They do....I save my soft lead now for hunting mostly... Use my free hard cast the rest of the time... A 100 lbs of lead goes fast in .510....Buying lead gets old fast...

Here's some bullets I fired at the range last week dug them out of soft dirt embankment gives a perspective of bullet expansion out of 2 different rifles.
The bullets on the left were shot from my XP Ranger at 25yds. Second in line from the Ranger at 50yds they have the deep HP, Third is a 300gr cup nose bullet fired from the Ranger and the fourth 300gr cup nose fired from my Texan at around 900fps the first 2 bullets are 280gr at 926fps and the third 880fps+-. All were accurate out of both rifles I love this bullet design and I'm going to try and get a mold in this design for my Badger 40cal.

I'm no expert but soo many variables on expansion. This link has a calculator to give an estimate of Wound Channel Depth / Penetration Calculator https://www.airgunsofarizona.com/Calcs.html . Below are vids on results of expansion, when I shoot into dirt it's totally different, doesn't expand nearly as much or uniform. So anything like bone or even thick pelt can change results. Look at this link to see 2 completely different results from same slug shot into a 5 gallon pail of water. 2 with the lid on and 2 without...just shooting through the lid plugged the hollow point and kept it from expanding at all. https://www.airgunnation.com/threads/interesting-results.1312200/

The results on the vids below are both using 60gn slugs made with the Thor Press flat base hollow point muzzle velocity 957 fps...rabbit was about 30yards out.

Just a general guidelines depending on what game you are hunting are listed here...good rule of thumb on needed calibers and fpe https://www.airgundepot.com/vault/articles/basic-airgun-hunting-guidelines/

Ezana4CE said:

@Vetmx That is definitely something that I am trying to keep in mind. Most of what I’m reading on projectiles relates to PBs. So thanks for the replies. It helps me focus on what is relevant and I’m pretty ignorant in this area.

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The way I see it is black powder cartridge ballistics is the closest to try to use as a reference to air! They are very similar, of course air is a lot cleaner and quieter