Chamber, I get the feeling that you're close and that your reply is for Mac, but for his question according the "ballistic coefficient" in the other thread...

but as far as I can understand you, I do agree with your remarks.

Though chambers' use of section density limited to like-bullets has the potential to provide more reliable prediction of penetration, my experience conducting terminal performance testing for bullet expansion and pentration has highlighted several realities that are contrary to common knowledge.
1. Kinetic energy, not velocity determines bullet expansion.
2. A bullet that has expanded to a larger diameter penetrates less than a bullet of a smaller diameter with the same or less energy (not velocity). 3. Bullets penetrate deeper as they slow down because they expand less.

I conducted 5 terinal performance yesterday with a 300 WinMag and thought of this thread. The bullets that expanded the least penetrated deeper.

If sectional density was applied with the bullet's expanded diameter and retained weight, than SD would be more accurate.

As an example, take a .277 130gr GMX (SD .242) fired from a 270 Win and a .308 165gr GMX (SD .248) fired from a 300 WM. At 500 yards, which bullet penetrates deeper? In the tests I have conducted, its the .277 bullet penetrates deeper because its expanded diameter is less than the .308, even though it has less energy.

Terminal performance testing
www.huntingnut.com/ind...sc&start=0

Bullet expansion vs kinetic energy
www.huntingnut.com/ind...=expansion

nah bro thats just cause .270s are better

It's interesting to watch the impact energy of the different caliber bullets. I can shoot .223 bullets into the bullet trap I fabricate all day long and still bring the box home. The box can absorb 8 or so .243 bullets. At 100 yards, the box is gone after 3 sometimes 4 shots from the .270 depending on the bullets. I stopped using the .308 Win because it wasn't providing enough energy to drive the .308 monolithic bullets to the bottom of their expansion cavities. I switched to just using the the .300 Win Mag (trading reloading development for use of his gun). With mild loads (150gr bullets at 3200 fps) at 100 yards, the front of the bullet traps were destroyed on the 2nd shot. I may need to come up with a better mousetrap.

I have been studying ballistic gel pictures and videos that are available online. It is easy to see the relative transfer of energy that takes place when a bullet expands and slows as it penetrates the gel. Exit "wounds are also interesting as bullets that fail to expand are still carrying much of thier energy as they exit while those that have expanded have usually have dumped most of thiers in the gel. I say usually as some bullets seem to transfer a constant stream of energy giving a wound channel that looks like a pipe and a nasty exit wound. I haven't tried to draw or even read any conclusions but find the subject very interesting.

I like such discussions. But you're only talking about the high-end stuff. Now let's try to compare that super-speedy monolithic to a soft lead round ball or conical when you hit an animal at 100 yards...
It would not surprise me at all that 1 shot with a soft lead conical in .45 or .54 would destroy you bullet trap completely. Remember that Englisman who shot elephants at 500 yards with a soft round ball in cal. 4...

Aloys, alls I have to test your suggesting with is a .45-70 rolling block and Oregon 405gr Bullets I could test with. However, the energy difference between a 405gr bullet at 1400 fps and a 150gr bullet that expands to over 1 1/2 times the diameter of the 405 grain at 3000 fps is not much of a comparison. I have tested a 150gr Rem CoreLokt in the 300 WM and it left the box completely untouched - it disintegrated and just peppered the outside of the bullet trap with lead and a it's copper jacket.

Oh, I do have 20 and 12 gauge lead slugs that are softer and hollow. Would these be a better fit for your suggestion?

SJ, no black powder fun? You could reload the 45-70 with BP and a soft lead pill...
And lead slugs in cal 12 or 20 have also a lot of energy on short distances. One remark: when you take hollow slugs it's my opinion that expand in lenght instead of diameter when they hit a harder surface. So then you get a complete other story.

I should calculate energy-levels, but I'm sure when you look at a 400 grs soft lead conical for a 45-70 at +/- 1000 fps, you'll find a superspeedy modern load at +/- the same energy level and it will be easier to hit your bullet trap at 100 yards with the 45-70 than with the cal 12 or 20 slug...

Aloys, I think your a nostalgic kind of guy. Thinking BP and heavy lead slugs can compete with a "superspeedy" modern load. My 45-70 at 1400 fps with a 405gr pill has a ME of 1763 ft-lbs. A 300 WinMag at 3200 fps with a 150gr pill has double the kinetic energy.

Note, I would set-up at 25 yards to do shotgun slugs.

What destroys my bullet trap is not the bullet but the water slug that forms in front of the bullet. The water slug is basically the temporary wound channel formed on impact with game. The quicker the bullet expands and the larger the diameter, the more impressive the results. I've recovered the copper jacket of several lead-core bullets that have dirt inside them. The only way that can happen is the water slug hits the ground and splashes dirt up in front of the bullet before it enters the box/bullet trap.

I'll set up some heavy lead bullet tests and report back.

SJ, just do it and be surprised

Its in the queue. Maybe this weekend.

Well, I finally got back from working in Northern CA and launched a 12ga foster slug into the bullet trap at 25 yards. It was 438 grains of lead leaving the muzzle at 1450 fps and 2045 ft-lbs of energy. Energy really drops with the slug and its 0.06 BC. At 25 yards it had 1475 ft-lbs. The smack on the water jug was impressive but it turned the slug into a lifesaver weighting 426 grains that yawed 90 degrees and over penetrated. The box 1, slug 0. Just not enough velocity retention to compete with monolithic bullets traveling with almost double the energy at 100 yards (example of recovered bullets shown). Thanks for suggesting, Aloy. It was fun and surprised to see I could hit the water jug on the first try.

SJ, I don't know I understand this right, what do you mean by "lifesaver"? And are you satisfied with the results of the slug or not? What do you think will hurt most: a hit with a slug from a cal 12 or a hit with a monolithic bullet from a .300 WM? (not that I would like to be hit with either of them)

Aloysius wrote:

what do you mean by "lifesaver"?

Note the impact knocked out the "hollow point" in the center of the Foster slug. I think they just put that indentation in the slug for marketing purposes. I probably should show a picture of the inside of the slug before its fired. The slug is basically the shape of a thimble. It will fit over your finger. In this situation, the walls of the slug just collapsed and the recovered slug is in the shape of a lifesaver candy.

www.google.com/search?...984%3B1024

Aloysius wrote:

And are you satisfied with the results of the slug or not?

Yes, though I likely would choose an alternative for hunting deer with a shotgun. I felt lucky I could hit a gallon jug at 25 yards and I think other options would have improved terminal performance.

Aloysius wrote:

What do you think will hurt most: a hit with a slug from a cal 12 or a hit with a monolithic bullet from a .300 WM?

Either is going to hurt. However, as far as lethality and wound channel, the indications are that monolithic bullets from the .300 WM have significantly more hydrostatic shock and a larger wound channel.

Slim, that is just with one type of slug mate...there are many different designs, and then there are those that are cast up by people like myself.

The Lee DRIVE KEY slug is surprisingly accurate mate. I have managed a four inch, three shot group at 50 paces from a smooth bore O/U. I cast the slugs from three different alloys...pure lead, Lyman Hard Ball (6/2) and Linotype. Point of impact was the same, however the deformation and penetration was very different, with the linotype penetrating approx four inches into a hardwood tree.

These are 12g Slug I cast up in different alloys:



Left to right they are: 1. PURE Lead, 2. 100% Linotype and 3. Tall Ingots Bullet Alloy. All were fired into a Eucalyptus tree at 50m.
The Bullet Alloy penetrated about 2" and the Linotype slug penetrated about 3" or 4" . The linotype slug had no deformation at all and was ready to reload, whereas the pure lead slug was flattened like a dinner plate.

It would cost a motza to buy a sample of each and every slug, because there are a lot of different designs, weights and manufacturing materials, e.g. nylon coated aluminium alloy.