max velocity for soft point bullets


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ralph2
November 12, 2010, 07:40 PM
Does anyone know at what velocity a jacketed soft point bullet will start to melt.
I have some 55gr 243 cal soft point bullets that I have just tested in my win 243
rifle at 3500fps that are not grouping well at all. One that hit the paper had a grey
smudge around the hole.

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243winxb
November 12, 2010, 08:25 PM
If the grey smudge is outward from the bullet hole on white paper, the tip is turning to liquid in the barrel.(in my gun) The air friction kept it melting or breaking down till it hit the target at 100 yds. The barrels groove diameter was larger than bullet diameter on my 243 with an 85gr spitzer SP. Some bullets will blow up before reaching the target (220 swift), high rotation speed, or damage done to the jacket from a rough bore. Your 55gr bullet is likely no sealing the bore. The nose/ogive of the bullet must seal the bore before the base of the bullet leaves the case mouth. If it does Not, then hot gas + air friction breaks the bullet down. Berger had some 6.5 bullets not making it to the target, long 30 inch barrels, more friction/heat at high RPMs http://benchrest.com/showthread.php?49336-Berger-bullet-failure-test :) From link, post #9 I am going to respond to your questions so that others who are reading this forum may learn what you seem to be unable to internalize.

Failures have several causes. The most common is produced by the core melting. The core melts because it gets too hot. The core gets too hot because of the FRICTION between the rifling and bearing surface. This has been proven to be the hottest part of the bullet as it moves through the barrel. This area has been shown in high speed, infared images reaching tempuratures at the melting point of lead.

Other causes for failure are excessive RPM. Since most shooters use factory (bullet or barrel) recommended twist rates failures due to excessive twist rates are rare (but do happen).

Rarer still is a failure caused by extreme barrel issues (damaged bore) extremely poor loading practices (damaged bullet) or extremely poor cleaning practices (which further increases friction).

Another extremely rare cause is related to bullet production issues. Bullet construction that is poor enough to result in bullet failure (and where bullet failure would not have occurred for any other reason) can theoretically occur in situations where standard QA and production procedures are ignored almost completely. I am sure that this is possible but is as unlikely as I can imagine (from all bullet makers).

These reasons for failure are true for all bullets. Bullets from every maker can experience failure under the right (or wrong) conditions. Recently, Sierra has made public that they are discontinuing the production of 6mm 117 gr DTAC due to repeated failures. I do not mean to pick on Sierra but this is a recent example. ALL BULLET MAKERS HAVE BULLETS THAT FAIL AND MOST FAILURES ARE CAUSED BY THE MELTING OF THE CORE.

:uhoh:

Walkalong
November 12, 2010, 08:55 PM
Velocity has nothing to do with it. While you might be getting blowby, as win243 suggested, damaging the bullet tip, you don't have a problem due to velocity.

Grey smudges from a bullet tearing through the target is quite common. If I shot you through paper at 3500 FPS you would leave a little mark too. :)

Welcome to THR

Damon555
November 12, 2010, 09:27 PM
Velocity has nothing to do with it. While you might be getting blowby, as win243 suggested, damaging the bullet tip, you don't have a problem due to velocity.

Grey smudges from a bullet tearing through the target is quite common. If I shot you through paper at 3500 FPS you would leave a little mark too. :)

Welcome to THR

What he said.

You will never be able to push a bullet fast enough to melt it in a .243. I've shot many 55 grain plastic tipped bullets out of a .243 without a problem @ 4000+ fps. Your gun probably doesn't like that particular bullet. Time to try a different bullet.

ralph2
November 12, 2010, 09:42 PM
Damon555 I just bought 1000 of the bullets so I am very interested in getting these to
work ! They are dogtown bullets from MidwayUSA.com. I am going to try them at
3300fps tomorrow

Steve C
November 12, 2010, 09:56 PM
I have heard people claim that they have pushed a bullet so fast that it came apart due the the centrifugal forces from the spin imparted by the rifling. Fired at a target at distance, no hole, and didn't know what the problem was until they moved the target in very close and could see the fragments on paper.

Don't know if it was just a story since I've never done it my self but I also haven't tried to push a bullet to the absolute maximum velocity that I could.

bubba15301
November 12, 2010, 10:41 PM
i had 87 gr ain bullets blow up in mid air fired from a .257 weatherby when fired you could see little blue puffs about half way to the target

243winxb
November 12, 2010, 11:16 PM
Some custom bullet makers claim that core melting takes place if oil is not removed from the inside of the copper jacket. The jacket spins faster then the lead core when in the barrel. Friction builds heat, the core melts. Sometimes vinegar is used to etch & clean the inside of the jacket so the lead has something to hold on to. One company has a patent on a process to bead blast the inside of the jacket so the lead bonds better, making a "bonded" bullet. Personally, i dont see the core spinning because the lands that are about .003" or .004" high would push the copper jacket into the lead core, keeping it from spinning at a different speed. :D

ralph2
November 12, 2010, 11:26 PM
243winxb - I like your statement that the bullet must seal the bore before leaving the case. I don't
think that is happening in my case because of the short bullet length (.596). Do you think a faster
powder might work better ? I used 42 gr of H414 in all my test.

243winxb
November 13, 2010, 09:16 AM
Do you think a faster
powder might work better ? I would guess, no. But its worth a try, that powder is a little slow for a 55 gr. IMR4895 is what i would try. We can not be 100% sure of what your problem is, as you can tell from reading above. More than 1 thing can cause bullet blowup, or a grey
smudge on the target. Very rare.

MMCSRET
November 13, 2010, 09:38 AM
Many years ago we were playing with an early version of a Sierra 52 gr. HP in a 28" barreled 220 Weatherby Rocket. The bullets came apart after exiting the muzzle, we were never able to get a velocity check on them as we did not want to damage the chronograph with shrapnel. It does happen!!!
I have never been able to get the light, short 6MM bullets to shoot well in any of my 6MM/243 rifles...wrong twist rate. All my rifles are older than the current crop of modern light bullets.

Blackrock
November 13, 2010, 09:49 AM
I was shooting the same bullet in my 6mm Rem at around 3200 fps gave me the best results. But I went up to a 87g Hornady HPBT and got my best results.
That 55g bullet is what I would call 'Light for caliber' in a 243/6mm.

Ol` Joe
November 13, 2010, 12:05 PM
I`ve seen too many pictures of high speed bullets in flight with tips intact to think they melt. You can run your hand through a candle flame slowly and feel nothing more then some heat, a bullets flight is over just about as quickly.

I think what you see as a "gray ring" around the bullet hole is carbon from gases that manage to reach around the bullet shank before it full obturates and seals the base from blow-by, and smeared on carbon from the sooty bore wiping off on the paper.

I have seen bullets break up due to speed and high rotation (45gr or 50gr? from a 22-250) with weaker jacketed bullet styles like the others have reported. they appear to be a short streak or a "poof" of smoke, or did to me.

rcmodel
November 13, 2010, 02:35 PM
I have seen the lead streaks radiating out a 1/4" or more around the bullet holes when shooting a 92 Winchester 25-20 with 86 grain jacketed bullets at 1,400 FPS.
So it isn't caused by high velocity.

I have also seen 22-250 bullets disintegrate in mid-flight at 3,600 FPS when shooting Sierra Blitz bullets designed for the .222 Rem. They leave a gray smoke streak in the air.
It is not caused by the bullet core melting, or air friction.
It is caused by the thin jacket coming apart due to high rotational speed.

The same or lighter weight bullets with a heavier jacket will stand all the speed a 22-250 can deliver and then some.

rc

NCsmitty
November 13, 2010, 02:57 PM
I just bought 1000 of the bullets so I am very interested in getting these to
work !

That's why you first buy a hundred to try.
I've seen too many new loaders who buy a large quantity of bullets, and load up 200-500 rounds and find out that the load won't shoot right. They try to skip working up a load and it comes back to bite them.
Then you have to pull them down or shoot them.
Everybody is in a big hurry to go nowhere.

Does anyone know at what velocity a jacketed soft point bullet will start to melt.


That's just a bunch of bull crap.



NCsmitty

788Ham
November 13, 2010, 03:20 PM
I used some Hornady SX, 50 grain .224 bullets some years back, around 3400 fps if memory serves me. Never could hit anything, especially Pd's with the outfit, Rem. 700 BDL. I came home totally disgusted.... then went to reload bench and found the problem! The bullet box had a piece of paper inside, under the bullets, stating the bullets had to be loaded at .222 velocities, below 3200 fps, as they'd come apart if shot at faster velocities! Might be your problem also, slow them down, might be able to keep better control at longer distance. JMHO

ralph2
November 13, 2010, 04:52 PM
I dropped the powder down to 2.5 cc (37.2 grains) H414 and shot 3 at 3300fps pretty much in
the same hole at 25 yds. At this velocity all I have is a hot 223 round. Next I am going to move
the target out to 50-75 yards and see what kind of group I get.

ralph2
November 13, 2010, 04:55 PM
788Ham -- MidwayUSA website says keep them below 4000 fps and all will be ok

788Ham
November 13, 2010, 05:04 PM
ralph2,

That's all good and well from Midway, but Hornady made the bullets! The "SX" means super explosive, and states they are made with a lot thinner jacket than normal bullets, keep below 3200 fps, I didn't see this until I returned home. Haven't used the rest of them, went to a heavier bullet. Midway sells them, but Hornady makes them.

rcmodel
November 13, 2010, 05:11 PM
And it's all related to rifling twist anyway.

They might be good for 3,200 with a 1/14 barrel, and not so good at 3,200 with a 1/7 barrel.

rc

ralph2
November 13, 2010, 09:49 PM
2.5 cc H414 (37.2 grains) 3 shots grouped about one inch at 70 yds. So unless someone has
and idea I guess I will have to settle on firing the at 3300 fps.

918v
November 13, 2010, 11:27 PM
A bullet does not spend enough time in the barrel for the lead to melt. The reason bullets come apart is the high rotational speed and fragile construction. Properly constructed bullets fly well in excess of 4300 FPS without coming apart.

Iloadntie
November 14, 2010, 10:09 PM
I had a couple of hundred cheap import bullets for my .223 for plinking they were coming apart before they reached the targret at about 100yds. I don't know why I just stayed away from those...

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