**Test Results** Forward Velocity vs Bullet RPM

[AllThingsAI]

I started a new thread to keep the results clean from the original post, i think they are getting lost.

Original thread here:
http://forum.accurateshooter.com/th...ty-vs-bullet-rpm-which-“hits”-harder.4011523/

Test:
.224 40g Vmax (Shot from .223's)
Velocity ~ 3300fps
1:12 and 1:8 Twist Barrels:
Expansion Media 1/8" Aluminum Plate

Here are the images of layers 1, 5, and 8. Each layer is 1/2" apart. So distance from layer 1 to 5 is 2". Distance from 5 to 8 is 1.5" Layer 1 was 1" from 1/8" thick aluminum plate. There are two pics. First is the front of layers 1,5,8, the second is the back layers 1,5,8. The distance markers on each card is 1" for measurement reference.

My Observations:
1. N=1 More testing is needed
2. I am able to track individual bullet fragments through the layers (will calculate spread average)
3. Overall fragmentation pattern diameter is approx. the same for both twists
4. Fragmentation for 1:8 twist, much larger pieces of bullet are distributed more evenly. Much darker color impacts (from lead core?) with larger holes
5. Fragmentation from 1:12 was patterned mostly to one side with very thin, slice like holes (to me this appears to be the jacket fragments. Much smaller impact holes with much lighter impact color (less of the core actually fragmenting?)

My conclusions from first test:
1. More testing needed (hard to draw conclusions from one test)
2. Overall diameter of fragmentation pattern is aprox. the same between two twists
3. 1:8 twist produced greater bullet fragmentation of the bullet core (heavier pieces dist. evenly)
4. 1:12 twist bullet did not fragment as completely (smaller bullet fragments creating small slices)
5. 1:8 first layer detection shows larger darker striations with bigger holes outside of main hole
6. First layer main hole is about the same size for both twists

 

[PigButtons]

Great work ATAI, you are definitely getting close. I am in total agreement that there is a difference, and that it is too soon to be too specific on what those differences mean.

It is curious that the center hole is as large as it is. I would have expected to see one to a few distinct holes from fragments rather than the complete removal of an area that large. What kind of debris was there in the bottom of the media box?

 

[AllThingsAI]

Great work ATAI, you are definitely getting close. I am in total agreement that there is a difference, and that it is too soon to be too specific on what those differences mean.

It is curious that the center hole is as large as it is. I would have expected to see one to a few distinct holes from fragments rather than the complete removal of an area that large. What kind of debris was there in the bottom of the media box?

My guess is the large hole is caused by both the bullet fragmenting (shotgun effect) as well as the aluminum being pushed straight out from the bullet penetration. Very nice clean holes through the aluminum. No debris as the box was hanging with an open bottom.

Side note, you can even see the rifling marks and twist differences in the holes in the aluminum...I thought that was pretty awesome. Hard to see in the pic, but clear in person.

 

[David Milisock]

I started a new thread to keep the results clean from the original post, i think they are getting lost.

Original thread here:
http://forum.accurateshooter.com/th...ty-vs-bullet-rpm-which-“hits”-harder.4011523/

Test:
.224 40g Vmax (Shot from .223's)
Velocity ~ 3300fps
1:12 and 1:8 Twist Barrels:
Expansion Media 1/8" Aluminum Plate

Here are the images of layers 1, 5, and 8. Each layer is 1/2" apart. So distance from layer 1 to 5 is 2". Distance from 5 to 8 is 1.5" Layer 1 was 1" from 1/8" thick aluminum plate. There are two pics. First is the front of layers 1,5,8, the second is the back layers 1,5,8. The distance markers on each card is 1" for measurement reference.

My Observations:
1. N=1 More testing is needed
2. I am able to track individual bullet fragments through the layers (will calculate spread average)
3. Overall fragmentation pattern diameter is approx. the same for both twists
4. Fragmentation for 1:8 twist, much larger pieces of bullet are distributed more evenly. Much darker color impacts (from lead core?) with larger holes
5. Fragmentation from 1:12 was patterned mostly to one side with very thin, slice like holes (to me this appears to be the jacket fragments. Much smaller impact holes with much lighter impact color (less of the core actually fragmenting?)

My conclusions from first test:
1. More testing needed (hard to draw conclusions from one test)
2. Overall diameter of fragmentation pattern is aprox. the same between two twists
3. 1:8 twist produced greater bullet fragmentation of the bullet core (heavier pieces dist. evenly)
4. 1:12 twist bullet did not fragment as completely (smaller bullet fragments creating small slices)
5. 1:8 first layer detection shows larger darker striations with bigger holes outside of main hole
6. First layer main hole is about the same size for both twists

Not to be a naysayer but two things. One I'm not seeing as much difference betwern the twists as you are. Two nothing we will shoot with 40 grain VMAX from a rifle will be as tough as 1/8" aluminum.

 

[AllThingsAI]

Not to be a naysayer but two things. One I'm not seeing as much difference betwern the twists as you are. Two nothing we will shoot with 40 grain VMAX from a rifle will be as tough as 1/8" aluminum.

Nay away! . Healthy debate is good, that’s all part of the process. I have the added benefit of being able to see the paper up close and in person.

As for aluminum I just have to point this out, it is not as hard as you think, very soft, much softer than say, bone which is as hard or harder and stronger than steel (Mohs hardness of 2.5 for aluminum vs 5.0 for steel/bone). Aluminum has the ~ hardness of a fingernail...plus it doesn’t matter, it’s the fragmentation of the bullet, due to twist rate, I’m studying.

Another interesting observation is the bullets pass clean through the 1/8” thick piece of aluminum and leave the imprint of the rifling. This shows two things. 1. The bullet itself is harder than the aluminum. 2. The bullet was still intact for the very short period it was in the aluminum.

 

[David Milisock]

Nay away! . Healthy debate is good, that’s all part of the process. I have the added benefit of being able to see the paper up close and in person.

As for aluminum I just have to point this out, it is not as hard as you think, very soft, much softer than say, bone which is as hard or harder and stronger than steel (Mohs hardness of 2.5 for aluminum vs 5.0 for steel/bone). Aluminum has the ~ hardness of a fingernail...plus it doesn’t matter, it’s the fragmentation of the bullet, due to twist rate, I’m studying.

Another interesting observation is the bullets pass clean through the 1/8” thick piece of aluminum and leave the imprint of the rifling. This shows two things. 1. The bullet itself is harder than the aluminum. 2. The bullet was still intact for the very short period it was in the aluminum.

I work with aluminum all the time I do signs, I was going to ask the alloy but didn't want to be an ass.

FYI a few years ago I was with another shooter who was shooting spining targets meant for non magnum rifles at 100 yards. He told me to shoot the spinner and I told him My 6MM would cut a hole in it. He said I was full of it. So I shot it and he said that I had missed. Until he looked through the spotting scope.

3/8" steel set up to spin when hit, shot at 100 yards with a 6MM Remington with a 75 grain Hornady VMAX muzzle velocity 3,900 FPS at 10 feet.

About a 1/2" hole cut straight through showing what looked like rifling grooves, (don't know why when the bullet is .243) the plate was hit so hard it never moved let alone spin.

 

[AllThingsAI]

I work with aluminum all the time I do signs, I was going to ask the alloy but didn't want to be an ass.

FYI a few years ago I was with another shooter who was shooting spining targets meant for non magnum rifles at 100 yards. He told me to shoot the spinner and I told him My 6MM would cut a hole in it. He said I was full of it. So I shot it and he said that I had missed. Until he looked through the spotting scope.

3/8" steel set up to spin when hit, shot at 100 yards with a 6MM Remington with a 75 grain Hornady VMAX muzzle velocity 3,900 FPS at 10 feet.

About a 1/2" hole cut straight through showing what looked like rifling grooves, (don't know why when the bullet is .243) the plate was hit so hard it never moved let alone spin.

6061

 

[kolar55]

3/8" steel set up to spin when hit, shot at 100 yards with a 6MM Remington with a 75 grain Hornady VMAX muzzle velocity 3,900 FPS at 10 feet.

Wow! What powder and how much to get that kinda speed?

 

[AllThingsAI]

Last Pictures, I promise. I'll quit boring the forum with my nonsense. I just find it all very interesting. Not trying to change peoples' minds, just trying to add knowledge to mine! Thanks for following along...Ryan

 

[Knotwild]

I'm enjoying your research AllThings. Thanks for sharing your research.

 

[PigButtons]

Last Pictures, I promise. I'll quit boring the forum with my nonsense. I just find it all very interesting. Not trying to change peoples' minds, just trying to add knowledge to mine! Thanks for following along...Ryan

I for one don't want you to stop posting. Please keep up what you are doing as it is adding to my knowledge as well.

FYI. One reason you see such clean holes with what appears to be rifling marks is that the aluminum is going molten under the extreme pressure of the bullet impact. I've seen slow motion of what is happening at that point and usually the bullet tip and the metal plate meld together until about the ogive. The rest of the bullet pushes out the molten mass but remains mostly intact. Since there is nothing to continue the collapse of the cylinder that was the bullet after the initial plate material is gone, further mushrooming / fragmentation does not occur. The plate itself is molten around the point of impact an therefore as the remainder of the bullet passes through it is like a hot soldering iron on soft plastic.
On the other hand, bullets that are shot at high speed into water have a tendency to become frangible and literally explode because the pressure on the leading edge of whatever projectile is still moving is hitting the same amount of resistive force as the first point of contact did.

 

[AllThingsAI]

I for one don't want you to stop posting. Please keep up what you are doing as it is adding to my knowledge as well.

FYI. One reason you see such clean holes with what appears to be rifling marks is that the aluminum is going molten under the extreme pressure of the bullet impact. I've seen slow motion of what is happening at that point and usually the bullet tip and the metal plate meld together until about the ogive. The rest of the bullet pushes out the molten mass but remains mostly intact. Since there is nothing to continue the collapse of the cylinder that was the bullet after the initial plate material is gone, further mushrooming / fragmentation does not occur Very. The plate itself is molten around the point of impact an therefore as the remainder of the bullet passes through it is like a hot soldering iron on soft plastic.
On the other hand, bullets that are shot at high speed into water have a tendency to become frangible and literally explode because the pressure on the leading edge of whatever projectile is still moving is hitting the same amount of resistive force as the first point of contact did.

That certainly makes sense to me! Any ideas or thoughts about the “residue” around the fragment holes? My thought is this is related to hot lead depositing vapor that is trailing it. Clean holes with no residue are either fragments of copper jacket or aluminum. Thoughts? I thought this was another interesting artifact of the experiment.

I certainly can keep posting and testing if people are enjoying it. It’s amazing what you can discover when you try to break things down. Your point about water is well taken...if I can come up with a narrow, fixed width column of water as fragmentation media that would be very interesting. I just want to avoid any hydraulic effect destroying the detection. Maybe gel with card stock molded in every 1/2”. I’ll need to think about that one a bit.

 

[357Mag]

Allthings -

Howdy !

I've been reading about shooting related matters for 48yr, and more recently doing plenty of reading off the 'net.
And I must say...... I've not seen the " bullet lands/grooves marks inside a hole in a metal plate " thing, before !
For me, that's a first; and your experiments strike me as novel & interesting. Please do continue to share.

The other day, you asked about ideas for potential testing mediums. FWIW - I have wondered about usefulness of latex mats ?
These are sometimes used to line kitchen shelves, and such. Materiel w/o an open weave would be best, most likely.
Also had a thought about use of kitchen plastic " cutting board " sheets. There are thin ones that are polyolephine, or some materiel along those lines.


With regards,
357Mag

 

[AllThingsAI]

Allthings -

Howdy !

I've been reading about shooting related matters for 48yr, and more recently doing plenty of reading off the 'net.
And I must say...... I've not seen the " bullet lands/grooves marks inside a hole in a metal plate " thing, before !
For me, that's a first; and your experiments strike me as novel & interesting. Please do continue to share.

The other day, you asked about ideas for potential testing mediums. FWIW - I have wondered about usefulness of latex mats ?
These are sometimes used to line kitchen shelves, and such. Materiel w/o an open weave would be best, most likely.
Also had a thought about use of kitchen plastic " cutting board " sheets. There are thin ones that are polyolephine, or some materiel along those lines.


With regards,
357Mag

Thanks 44Mag! You’ve been upgraded...again! Pretty neat to see the rifling marks, and be able to distinguish land groove sizes and twist! some of the ancillary effects from a test can be more interesting than what your actual trying to test! These “vapor trail” marks around the holes have me fascinated as well...I never expected those either.

I actually thought about something close, I had some vinyl mat used for drawer bottoms. A thick build up of those would be interesting, kind of an in between material (between solid and liquid). @PigButtons brings up a really good point and an excellent analysis of bullet impact of aluminum and water based objects. I need to figure that one out as well in a way that I can print the fragments path and not make a disaster of everything.

ATAI

 

[Bocephus]

My guess is the large hole is caused by both the bullet fragmenting (shotgun effect) as well as the aluminum being pushed straight out from the bullet penetration. Very nice clean holes through the aluminum. No debris as the box was hanging with an open bottom.

Side note, you can even see the rifling marks and twist differences in the holes in the aluminum...I thought that was pretty awesome. Hard to see in the pic, but clear in person.
View attachment 1192977

Remarkable Observation!!!

 

[CharlieNC]

The FBI labs have done extensive testing of bullet performance when passing through many types of hard surfaces and body tissue. As I recall there are major performance differences between the media, so optimizing through boards will not likely translate to animals. Not that this is necessarily your intent, but a caution.

 

[David Milisock]

6061

Thanks.

 

[David Milisock]

3/8" steel set up to spin when hit, shot at 100 yards with a 6MM Remington with a 75 grain Hornady VMAX muzzle velocity 3,900 FPS at 10 feet.

Wow! What powder and how much to get that kinda speed?

Reloader 19, 53.5 grains with a 26" barrel. 75 grain VMAX moly.

 

[ebb]

There was a lot of testing like this only done on pig and cattle carcasses in a slaughter house when powdered tungsten bullets were developed. I don't know it any of it is still on the net. They were called Bubbas bullets I think.

 

[ebb]

DRT Dynamic Research Technologies check out the website.