Home Forums Hunting & Shooting Ask The Gunwriters Fresh Evaluation of the "Copper Bullets"...

I wouldn't either. There's no such thing as centrifical force. It's called centripetal force. You could also use centrifugal force but real physicists don't.

I beg to differ. Unless physics has changed since I took statics and dynamics in college, centrifugal force is the OUTWARD force and centripetal force is the INWARD force.

Forgive my spelling. I'm not a physicists(thankfully).I might get bogged down in my own bullshidt rather than approach these things with an open mind,and observations.

-Ever see a 90 gr HP fired from a fast twist 264 Win Mag fragment in thin air before it reaches a 100 yard target?I have because a friend used to do it regularly and we'd watch the puff of smoke at the range for entertainment.It isn't the speed that causes that...it's rpms tearing scored jackets apart.

-Ever wonder why Berger beefs up jackets for its' high BC target bullets,fired from fast twist barrels,because thin jackets were coming apart in mid air if started too fast from these fast twist barrels?(again, high rpm's).If they will come unglued in thin air, what makes you think that the additional stresses of impacting at high velocity would not be aided and abetted by high rpms's.

-Ever see two bullets of the same weight and design recovered from animals shot under similar conditions,one with the expanded wings at 90 degrees,and the other with the expanded wings off at an angle,and with greater expanded frontal area,fired at higher velocity and a faster twist(both resulting in higher rpm's)? Ever wonder how that happened?

Ever wonder why Bitterroots came with instructions to use a minimum twist rate and velocity level to ensure proper expansion? It might dawn on the clueless that the maker ran extensive tests and proved that higher rpm's resulted in greater and more certain expansion than the same bullet fired at lower velocity and fewer rpm's.But I doubt you've seen that because these tests were run 30-40 years ago;beyond the knowledge of flks who think this shidt is somehow "new" and all ballistic knowledge is less than 3 years old.

If you doubt it, call the maker and ask him...you'll probably be lost in the first 10 minutes of the conversation,much of it being excessively over your head.

-Ever wonder why varmint hunters have noticed greater "explosiveness" from bullets fired from fast twist barrels vs the same bullets at the same velocities from slower twist tubes? You would only notice this if (a)you shoot a lot of varmints;and (b)you pay attention.

-Ever wonder why reduced loads fired at close range to simulate expansion speeds at distance are invalid for testing bullet expansion at distance? Know why? Because rpms' are not anywhere near as high as the same bullet fired at actual distance under full velocity.Might also look into how this effects wound cavitation with expanding bullets that don't fragment;that is if you ever used one..

Those doubting this stuff are likely the same one's who say ..."200-300 fps does not matter"...."rpm's do not matter",nothing matters,and everything ballistic can be explained from the couch with numbers....what a laugh this place is sometimes. .

Num

Yet another factor in expansion of monolithics is the size of the hollow-point: The bigger the hollow-point the more reliably and widely they open, everything else being equal.

This is a large part of why the plastic-tipped TSX's tend to expand wider and more reliably than the plain hollow-points: The hollow-point under the plastic tip is larger, at least in the smaller calibers, say .30 and under.

Plus, the Tipped TSX's retain more velocity.

Bang on.

Also bang on.

Meaning what?

Bang on, spot on, correct etc etc.

Ok thx. Wasn't sure whether it was an "attaboy" or an "aw sh1t".

Obviously Bob doesn't have anything to cite regarding monos opening wider at higher RPMs.

What happens to cup and core bullets is not going to be the same thing that happens with monos at similar speeds and I am pretty doubtful it would be even an applicable comparison at much higher RPMs because no one to my knowledge has yet demonstrated that over revving a mono to the point of self destruction is even possible.

We have long known that running cup and core bullets into flesh at very high velocity and RPMs can produce explosive results. But, we also know that we can do the same thing more or less at well below the threshold of self destruction.

Does anyone have anything??? Does anyone know if holding velocity constant and increasing RPMs increases expansion with monos? I know that if I run the velocity high enough I can shear petals, and that has a tendency to increase penetration from some limited test results I have seen.

We've know from the get-go with the monos that their increased length responds better to fast twist rates, seems a little odd we haven't done the experiments yet.

I would have thought if faster twists make cup/core bullets expand more, it would do the same with copper bullets, to some extent at least. After all they are all metals.

I can hear the howls of derision because my opinion is not based on 37 experiments with 4000 data points: "Experience trumps opinion every time" etc etc.

Anyway whatever reason someone goes onto an internet forum, I didn't come on here because I am a scientist. But most good experiments have their origin in mental experimentation.

All I can add is: cue the soaked newspaper test.

I have a hard time thinking the laws of physics are somehow suspended when bullets are monolithic. I also have a hard time believing there is a downside to more forward or rotational speed. Perhaps, when it comes to monos anyway, temperature is even a significant factor.





???

The laws of physics don't change. But the properties of materials do. Copper has more tensile strength than lead. So it takes more force to pull it apart

This is just a hypothesis. I have no data:

As Bob noted, a thin jacketed varmint bullet is more likely to disintegrate in air than a big game bullet with a thicker jacket and a harder lead alloy core.

So it seems likely that a solid copper alloy bullet would be able to resist even more rotational stress. In other words it could provide more centripetal force so as to resist a higher centrifugal force.

Similarly, a copper is more resistant to deformation upon contact with animal flesh. Which results in higher weight retention and deeper penetration.

I asked Barnes about spin rate vs expansion. This s what I got back.

" In theory increased rotational speed will damage more tissue, but in reality it is such a minor amount it would be very difficult to even detect it. There is a maximum rotation speed, for most bullets, jacket bullets can and sometimes do come apart in air if they are spun too fast. The Barnes bullet�s the all copper bullets cannot be spun to fast to come apart so as far as function it cannot be spun to fast, as far accuracy is concerned, spinning them too fast can be detrimental to accuracy. We have not seen any indication showing that jacketed bullets open wider because of rotational velocity, but with the all copper bullets we have seen enough evidence to suggest that they do not open wider due to the rotation of the bullet."

Bluntly then, at least in the case of Barnes bullets increased expansion due to increased spin rate is wishful thinking. Whether there might be increased tissue damage due to increased spin rate if we radically increase spin rate remains open but in doubt because of the probability of accuracy loss.

Maybe we should think about building a test rifle to see what happens. Right now the rifles we use them use copper bullets in are designed primarily for cup and core bullets and not exclusively for copper. Some of our barrels are very fast twists, but not into the range where just copper can handle to RPMs yet.

Miles,

To put it mildly, I don't think Barnes has any clue about the effect of rotational velocity, based on their statement, "We have not seen any indication showing that jacketed bullets open wider because of rotational velocity."

There's been plenty of evidence of that. Anybody who's used a fast-twist .223 has seen it, but evidently Barnes has missed it.

Also, the point we were discussing wasn't whether increased rotational velocity would case monolithic bullets to open wider than they're designed to. Obviously, they can only open so much.

But there have been numerous instances where monos DIDN'T open fully, or at all, at longer ranges. Would increased spin have helped? I have no doubt it would, based on what other bullets do when spun faster.

Does greater centripetal force reduce over penetration?

John,

I wouldn't be all that surprised that they didn't know, or at least the person who answered my question didn't know. Maybe though their response is just exactly what it says, and a hgh RPM bullet coming undone in a target is not necessarily "opening wider".

My experience with more damage from high RPM bullets causing more damage has been with high velocity in addition to high RPMs with smaller targets. That putting the bullet a lot closer to coming undone seems to matter. 14 twist vs 9 twist in .223 & 22-250 gives me the impression that velocity is much, much more critical than RPMs. The numbers and size of target sample are not huge though.

Might be an interesting experiment to take the same bullet in a 9 twist .223 and a 14 twist 22-250 and catch some in water jugs matching velocity to see what happens to the bullet.

I been telling that to Brad forever. He keeps showing pics of a 53gr TSX shot from a 1-12" twist in apparently cold weather. Cold DO matter when discussing bullet stabilization.

I'm not one that goes with the minimally stabilized is good enough. [bleep] that.

Miles you just aren't going to convince me...and neither is Barnes.

Like Johnny B has alluded to in another thread,you can't assume that bullet manufacturers know everything about their bullets because some times they never try them out to see what they really do.

Did you ask them how many tests they have run in expansion material with progressively faster twist to see the results?That would have been my first question to them.If they haven't,and don't know, well,they simply don't know.

Monos may have different expanding characteristics but based on some to the pics posted above,it appears sometimes they do need all the help they can get just opening to a meaningful frontal area at all.I'm not suggesting the differences are enormous, but I know if I were a Barnes user, I would be turning them over,and driving them,as fast as I could to assist in expansion.It's apparent from their construction that they will only expand so far,like John says....but personally I would like to be certain they do expand as far as they are able.

The guy who opened my eyes to this stuff, was Bill Steigers,who developed the Bitterroot bullet. Rather than guess at this stuff,and debate it ad nauseum,Bill ran his own tests,which were pretty much ongoing over the years.I knew him in the 80's...far as I know, he had been doing these tests since the late 60's.

He did it with bullets from 270 caliber to 375,and IIRC I recall Bill building 7mm barrels with 7 twists,375's with 9 twist tubes etc.Way faster than considered normal for the day.

..reason was that his bullets were very heavy through the jackets,pure copper,and lead cores and bonded....they were built to withstand very high impact velocities,and will expand and retain frontal area better than a Barnes.They were pretty rugged.

What he found is that faster twist facilitated greater expansion,and he was so adamant about it, that his bullets came with a small spec sheet recommending that they be driven at a certain minimum velocity,and in a certain minimum twist for best results.

Since Barnes bullets are made of pure copper(supposedly),and Bitterroots were made with heavy jackets of pure copper as well, I see no reason why the copper in a Barnes could not be lent an assist in expanding,and as John says,it may help expand them at long range;and sometimes maybe up close as well.

In any event,that fast twist has a hand in expanding bullets is such a well settled issue,and is such a relatively "old" conversation dating back decades I am really surprised that it generates so much conversation on here whenever the topic crops up.All I can conclude is that some are simply not aware of it even today.

Miles,

I performed a better test than the one you suggest last summer with the new 55-grain Nosler Varmageddon bullets and prairie dogs. Used both my tang-safety Ruger 77 .220 Swift with the bullets loaded up to 3800 fps (1-14 twist) and a Nosler Varmageddon AR-15 .223 with their factory ammo at 3100 fps (1-8 twist.

The difference in expansion was VERY apparent--with the advantage going to the AR-15. Ranges were from 100-300 yards, and the experiment was repeated many times throughout the day.