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Hollow point at high speed, vs accuracy.

Discussion in 'Handloading and Reloading' started by ACES&8S, Dec 5, 2019.

  1. ACES&8S

    ACES&8S Member

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    Starting this I questioned the validity of it, yet I have often wondered what happens to
    a hollow point at terrific velocity like the one I have in my attachments, a Sierra165 gr HPBT
    in .308 out of a 300 Win Mag.
    I don't know the B.C. of it but probably low.
    But what I wonder about is, the HP is square in shape & at 3,200 fps would that deform
    the HP at some point?
    I know it sounds stupid but open air with high humidity is resistance isn't it?
    I found this box I had laid back several years ago, just wanted to try it.
    I have several 30-06 & 308 & also have a Ruger Precision in 300 Win mag.
    Any thoughts? Hollow Point#1.JPG Hollow Point#2.JPG
     
  2. Slamfire

    Slamfire Member

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    High velocity in air will not deform the nose of the bullet. Too high of velocity and thin jackets have caused bullets to "blow up" on the near side on the hides of animals. And I have seen the gray puffs in the air when bullets shot out of a rifle at too high a velocity fragmented. I guess the rotational stress on the jacket causes the bullet to fragment in the air.

    {At one highpower match, during the first stage of sitting rapid fire, the target to my left reported insufficient. The shooter did not ask for an alibi, which was unusual. One the second stage, similar results, but this time, I asked for the number of hits, and was told none.

    Back on the firing line, during the relay change, I asked John, the shooter, what had gone wrong. John said he was shooting some cheap 223 bullets and they had fragmented in flight. And for his second string, instead of shooting five and five rounds, he loaded his 20 round magazines with all the cheap bullet rounds he had and fired them all off ! Not one kept its integrity and reached the target face!}

    Jacketed bullets have to be built to expand within a limited velocity range. And that is why manufacturer's have velocity recommendations.

    Based on a web search I found a calculation that a bullet moving 984 fps creates 22.68 psia of air pressure resistance. I am certain, no velocity you can push a bullet at will cause the nose to collapse.
     
    Last edited: Dec 5, 2019
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  3. ATLDave

    ATLDave Member

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    Contrary to your intuition, humid air (without actual raindrops in it) offers less resistance than air of the same temp but drier. Water vapor is less dense than air. That's why a storm front moves in and the barometric pressure drops.
     
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  4. Laphroaig

    Laphroaig Member

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    I agree. In answer to your other question, due to the blunt meplate, it does have a relatively low BC for a boattail.

    I used to use that bullet for whitetail hunting years ago in a 30-06. It was devastating, and I downloaded my ammo to help with meat damage. I've moved on to other 165 gr. bullets that don't expand as rapidly. I'd hesitate to use it in a 300 Mag.

    One positive is that the tip doesn't get deformed in the magazine due to recoil. I hate when that happens with exposed lead softpoints.
     
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  5. ACES&8S

    ACES&8S Member

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    I don't know where it might be going with this thought but, a bullet is OBVIOUSLY heated when it is launched
    thru the barrel INSTANTLY so moving thru the air wouldn't be cooling it, it would have to be sustaining the heat
    with such speed. So this would assist the bullets function on impact since it is already at or near blacksmith heat.
    When I was about 21 years of age I was with my cousin on an abandon strip job & we both shot at the frame
    of an ABANDON vertical drill with al I remember was thick metal, his 30-06 bounced off, my 7mm Rem Mag
    went thru the steel = a hollow point he had loaded for me.
    We drove around the road to get to the drill, about 2 minutes.
    Couldn't find his bullet, it had vaporized but mine had gone thru the steel dented a wall behind it retained it's
    mushroom shape & lay between the 2 walls I had to reach way back in there to get the remains of the bullet.
    It instantly stuck between two fingers with frying pan heat like the eye of an electric stove & I had to beat
    it off my fingers with my other hand.
    I don't know the bullet or the load he used back then but to shoot an HP thru steel & it remain in mushroom shape
    sounds impossible, but remember this part, the bullet was heated by the rifle THEN probably super heated by
    the steel penetration, that is 2X, & retained it's intended form yet his 06 bounced or scattered.
    He probably overloaded the rounds but it doesn't account for the weight retained.
    He also loaded his 22 hornet & couldn't get it on paper at 100 yards, because the bullets were vaporizing out
    of the barrel = hollow points.
    Any thoughts.
     
  6. jmorris

    jmorris Member

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    The base of the bullet is the important part, it is made most uniform if the end of the process is opposite of it.

    Not a lot of open base FMJ bullets used in benchrest, lots of HP’s.

    Then one can also stuff the HP with something else. Hornady was one mfg. that does so and just a year or so ago discovered the plastic they were using was melting, so they now use a new plastic. Not sure if they called the first one or 2nd one a “space aged polymer” but that just means plastic.

    Copper has a quite high melting point. I have seen bullets come apart due to centrifugal force though, light jackets and too fast of a twist rate for the velocity will do it.
     
    Last edited: Dec 6, 2019
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  7. ACES&8S

    ACES&8S Member

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    I had a VERY DEAR FRIEND that passed away 2 years ago.
    He started me into reloading back in [ 1976 ] & taught me so much about deer hunting, I miss Jim so much.
    I remember my very first buck was a small spike & I had to hang mine beside his 8 pointer which made mine
    look like a fawn, but I was so proud of my first rifle kill I felt I was a threat to the champ at that time.
    I had done bow kills before but not a rifle.
    Anyhow, Hollow points, Jim was a 243 LIFER & neck shooter also believed in maximum load+ with hollow points
    which I saw for several years hanging in our shooting range later. They actually looked like someone held a grenade
    against the hide with a blast radius of 6 inches, then if he had to shoot anywhere else there was always at least
    2 shots unless it was right over the heart.
    I remember the last time he was here to sight in his rifle I had a fire extinguisher beside the target in case his
    --- hair burner --- lit my backstop on fire. Just joking with him.
    So many of my old hunting friends have gone.
    Sorry I got off subject.
     
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  8. ACES&8S

    ACES&8S Member

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    RETRACTION :
    Called my cousin, the whole story about the penetration was true: EXCEPT, there was no lead, only the
    brass hull in a perfect peeled back mushroom shape after going thru the steel wall.
     
  9. Varminterror

    Varminterror Member

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    I’ve been trying to think about where to start with an answer here, but there’s just so much wrong with the assumptions about bullet temperatures, destructive forces of air within the nose (neglecting ALL KNOWN SCIENCE around bluff bodies in motion).

    Thinly jacketed hollow point varmint bullets can be pushed hard enough in some cartridges to exceed 4,000fps, and they are never forced open in flight. The only thing tearing bullets apart in flight is the centripetal force from the spinning mass of the core exceeding its structural integrity.

    The exaggeration of air resistance frictive heating vs. the increased cooling rate due to high velocity and the massive heat sink which is the atmosphere, exaggerated air pressure within the (largely static) nose hollow, neglecting the fact bullets would be at their highest velocity at the muzzle, opening immediately, and flying like a wiffle ball because the body would suddenly increase in drag... just way too much pseudoscience... over-thinking without actually thinking.

    Take heart - we shoot hollow point bullets to exceptional speeds, and none open up in flight. Boat tailed hollow points are among the most accurate class of bullets in the world, at almost all ranges (ELR firmly dominated by massive solids).
     
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  10. ATLDave

    ATLDave Member

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    Air frictive heating is a real factor for airplanes north of mach 2. There are some historical aircraft whose Vmax limits were set by the speed at which the (usually aluminum) skin would be damaged by the heat of faster speeds. And some rifle bullets are operating at similar speeds.

    But supersonic fighters are going fast for minutes at a time. Bullets aren't in flight for very long... a few seconds. Whatever heating is happening with an in-flight bullet, it can't happen nearly fast enough to soften or melt the bullet.
     
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  11. ACES&8S

    ACES&8S Member

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    That is the kind of reply I wanted to hear.
    The only reason I picked on the bullet in the photo I used is because of the SQUARE design.
    Just thought I might stir up some fight or flight among the hollow point users.
    Seems defense has taken the day off.
    I knew a Fighter Pilot who saw action & received lots of recognition but has passed away.
    We asked him a simple question one evening.
    Does the jet get wet during low level attack speed during a rain storm?
    He said I will have to think about that, I will tell you in the morning...………..
    ……...
     
  12. Varminterror

    Varminterror Member

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    bingo
     
  13. mcb

    mcb Member

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    I though this was part of the premise of Hornady's new EDL-X bullets, that the polymer tips of many bullets are deforming or ablating due to aerodynamic heating.

     
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  14. ATLDave

    ATLDave Member

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    Sure. A little plastic doo-dad doesn't have much thermal mass, and might have a softening point at, say, 140° F. A copper jacket that has a lot of surface area to conduct heat into a big lead core and anneals at 700° F... totally, totally different.

    ^ I know you know all of this and could surely show us all the relevant equations. Just offering clarification for readers.
     
  15. ACES&8S

    ACES&8S Member

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    That is very educational for myself, I have always suspected this to be the facts but an SST in itself is a HP with
    a doo-dad as ATLDave calls it or as my son calls it, a PistonPoweredHollowPoint.
    While on that subject of doo-dads, I have a box of Hornady Flex Tip = FTX 325 grain 45/70 which are about as
    flexible as the brass case they are in.
    I don't trust them in the Marlin tube. Just one at a time or use them in the Encore.
     
  16. Varminterror

    Varminterror Member

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    As @ATLDave pointed out - there’s a big damned difference between deforming a polymer with a relatively low thermal tolerance and melting copper and lead. Also as he pointed out - we know you know better than baiting...
     
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  17. mcb

    mcb Member

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    Did not mean to come across as a troll with that post. I just remember the launch of the ELD-X bullet and that Hornady had found fairly conclusive evidence of the polymer ballistic tips were being damaged due to aerodynamically heating and it seem appropriate to the thread. I was in a rush and just sort of flung the post at the thread and ran (notice my usually long winded rambling is missing from the post). I did not mean to imply that the metal aspects of the bullet would be adversely effected by the limited aerodynamic heating only that some bullets (with polymer tips) are adversely effected, to a small degree by heating from high velocity and that might be of interest to the thread.
     
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  18. ATLDave

    ATLDave Member

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    I thought you were just funnin’ us!
     
  19. Varminterror

    Varminterror Member

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    As did I.

    Fair play then, @mcb.

    I’ve mentioned here before, I had a “gun guy” hosting his own table at a show once tell me 1,000 yard shooting was impossible (as I was considering a 7mag Sendero on his table), because bullets completely “sand” themselves away to nothing before they even get past 600 yards... with an absolute straight face. Even young and naive at the time, I knew better than to give him my money.
     
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  20. jmorris

    jmorris Member

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    That’s the one I was talking about in #6. I guess a year or two turns into 4 quicker than it used to.

    You could turn the plastic tip into ash and all the lead would me
    T and run out of the end before you could melt the copper.
     
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  21. Walkalong

    Walkalong Moderator Staff Member

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    Now that's a good one, ranks right up with the worst I have hear at gun shows over the decades.
     
  22. Bill M.

    Bill M. Member

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    I shot a 5/8 inch group with 75 grain hollow points at about 3200 fps the other day. I was a little disappointed that it was not better. I used to shoot those same Sierra 168 gr HPBT in my -06 with good accuracy but not quite that fast. 2700fps if I remember right. I think you will be fine with them in the .300. Maybe even the bullet of choice.
     
    Last edited: Dec 7, 2019
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  23. ACES&8S

    ACES&8S Member

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    Been looking at them to do overkill a bit.
    We have bear here on our property but I have never taken one but they are beginning to become a bit
    to numerous to ignore also there are a few children that live a few hundred yards from here & they ride
    bikes where I have been able to see bear FAMILIES crossing the road. Doesn't help to take just the males when the
    females seem to be the only real problem. But there are some real whopper size bear here, the would be state
    record was killed with a car a couple of months ago only 4 miles away & it went 792 pounds.
    Getting to be a long of a story, so, if I get a shot at one it will be out from 250 to 300 yards & in my health condition I
    don't need to be tracking or dragging one so I want to use a real Nose In The Dirt round & my concern isn't wasting
    meat with bear like it is with deer. Looks like a very lethal destructive bullet, just been wondering how 3000+ would
    make it run. I know the hull won't peal off or SAND DOWN to a 22 caliber at 300 yards.
    My real concern is the SQUARE hollow point accuracy at 3000+ fps.
    Most males seen around home here of real size are like 250 - 300 pounds.
    Walked around the house between mamma & cubs once Then another time a mamma caught me kicking leaves
    in her cubs face trying to run the cub off, she would have gone 4 or 5 tons by he act. Just shoot a 357 in the ground they
    leave you alone ----------so far.
    Can't bait anything in this state they just tie goats to trees like Jurassic Park.
     
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