Mid Air Explosion?

[Osage]

Was helping my son test some 223 loads today. We were shooting the Midway 50 gr dogtown bullets over varget. One shot had a strange mid-air poof of smoke about 10 yards from the rifle. It was fairly large. Never saw that before. We were shooting through a chrono and that load for some reason was quite a bit faster. Did some unburned powder come out in a clump and burn mid-air? The load was 27 grains which fills the cart and is compressed. I checked my Lee manual and Hodgdon and both list 27.5 as the max.

[mrawesome22]

Bullet came apart in flight.

It happens.

[Osage]

That would explain why we were one hole short in the target. Too cool.:cool:

[g.willikers]

Short fuse?

[rg1]

I'd guess that the bullet came apart, jacket separated and a poof of lead dust.

[Scharfschuetzer]

Do you have a 1 in 7 or 8 twist on your son's rifle? The fast twist barrels really rotate the bullets fast and the lightweight varmint bullts with thin jackets will, as you noted, come apart.

Some quck math with some assumptions on my part:

Your 50 grain bullet from a 1 in 10" twist barrel at 3300 fps has a rotational speed of 3,960 rotations per second or 237,600 rotations per minute.

[Osage]

Not really sure. It's a Savage model 10 with the long bull barrel. I used to know this...

[scsov509]

Do you have a 1 in 7 or 8 twist on your son's rifle? The fast twist barrels really rotate the bullets fast and the lightweight varmint bullts with thin jackets will, as you noted, come apart.

+1, I've had that happen in my 1:8 twist with Barnes Varmint Grenades

[Slamfire]

I was in the pitts pulling targets when the target on my left came up with insufficient during 200 yard RF. There might have been a couple of holes but not the ten needed.

Next string the target still had insufficient, maybe a couple of holes.

When I got on the firing line I asked the shooter what happened.

He was firing a .223 AR15 with cheap .223 bullets. They were blowing up in flight. His second string, he completely loaded his 20 round magazine and shot them all off in his 60 second rapid fire string! Having been down in the pitts I can tell you, 20 bullets did not make it to the target.

[jaguarxk120]

27 grains of what powder? If it is a comressed load -- seems like it's too close to max.

[243winxb]

The bullet jacket gets damaged by a rough throat/leade. This causes it to come apart. Give the rifle a good cleaning with solvent and brush.

[Peter M. Eick]

I used to do that with my 220 swift for kicks.

On a calm morning, the lead will melt out of the bullet and leave a sort of faint misty smoke line from about 15 yrds out to when the lead is gone.

The target would normally get hit with fragments of copper if it got hit at all. Once the lead was gone, the bullet would go pretty wild.

[thallub]

On a calm morning, the lead will melt out of the bullet and leave a sort of faint misty smoke line from about 15 yrds out to when the lead is gone.

In the early 50s i inherited a model 70 Winchester in .220 Swift and started reloading ammo for that gun. Some of the .22 caliber bullets would not stand up to heavy .220 Swift loads and we had some "blue streaks".

[semi_problomatic]

Now that sounds like fun. Does it foul your barrel pretty bad with lead or is it all pushed out? I read about tighter twist seperating light bullets, never knew what it looked like.

[Osage]

Might explain why I see vapor trails behind my 6.5 swede? I found that very odd.

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[hornetguy]

naaah.... you see vapor trails behind the bullet on your Swede cause it's just such a COOL rifle...:cool: :D

I watched a guy at the range after he said "watch this"... he was shooting an AR with a fast twist barrel, and EVERY shot would disintegrate the bullet about 20yds out.. He told me that his load was a little too hot for that bullet. I said, "you think?"

He's the guy that would scotch tape dimes to his target at 100 yds and poke holes in them with one of his AR's... didn't miss them very often.

[FrankenMauser]

Midway claims that the Dogtown bullets can be pushed up to 4,400 fps... but most people experience unsatisfactory results, even at velocities as low as 3,700 fps. My own results (.220 Swift) were no different.

As other posters have stated... your bullet was so far beyond being "over stabilized", that the centrifugal force actually ripped it apart. With certain bullets, you'll see it happen far more often in dense air (cold weather or significantly lower altitude).

[Magnum Wheel Man]

FIL used to love the 17 Remington ( bear in mind this was like 22 years ago ) he had a hard time loading to the top loads in the manuals & not have his bullets misteriously disappear in mid flight... ( like they were abducted by aliens... from Mexico or something ) ;)

as pointed out, the rotation is like crazy rpms... it's not uncommon to have either damaged enough, or gotten a bullet just not quite right, & have them come apart mid flight

[Unclenick]

Osage,

I believe your Savage has a 9" twist. If the Dogtowns claim to tolerate being pushed to 4400 fps, presumably that's in a 14" twist barrel like the 220 Swift usually has. With 9" twist the same rotation rate will occur at 9/14×4400 fps or 2829 fps, and that will be your explosion proof upper limit. I'm sure you're well above that.

Since we don't know what powder you are using, it's impossible to guess at your velocity, but it's probably high. I'll suggest that any powder you need 27 grains of with a bullet that light is slower burning and less efficient for best work with it anyway. Especially if it is spherical, there is a chance of getting bullet base secondary pressures near the muzzle (see example in pressure plot below) and that could contribute to bullet distortion not to mention possibly causing barrel ringing over time.

On top of that you are wasting powder money. Something in the range of 18 to 19 grains of IMR 4198 would give you all the velocity that bullet can be sure to withstand with your barrel twist rate. You can then experiment with working it up faster to 21.9 grains, Hodgdon's upper limit and 3350 fps in Hodgdon's test barrel, and see where the bullet loses reliability. It's groups will probably start opening up by then, anyway, so I'd just stop where the accuracy is best.

I think you are spinning the bullet beyond its limits, but take the suggestion to clean the barrel well anyway. I like Boretech Eliminator (http://www.boretech.com/docs/articles/precisionshooting_jan.pdf) best for this. Put a couple of wet patches through using a plastic Hoppes jag (Eliminator eats brass jags), let it sit 20 minutes, then repeat until the blue stops coming out.

With kind permission to reproduce from Jim Ristowe at RSI:
http://www.shootingsoftware.com/images/sampletracebump.gif

[mete]

'vapor trails ' ? Perhaps smoke rings ? Search for photos of smoke rings from a big 12" or 16" naval gun , that's VERY impressive !! :D

http://civilianmilitaryintelligencegroup.com/11289/us-naval-gun-fire-photos

Found it , these are REAL guns !! :p

[Osage]

Powder was varget. Only one busted up. We settled on a lighter load and got great accuracy. I forget what the chrono said but if I remember correctly that one round was higher than the others. Fluke or loading error.

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[Unclenick]

Hodgdon thinks you'd be at around 3400 fps with those bullets, so that probably gives you an idea of the true limit. You might aim at 3000 fps instead and see if they hold together and stay accurate.

Varget is liked for heavier match bullets in the .223 Rem. You may be able to get the 77 grain SMK to stabilize in your 9" twist bore OK, too. It's heavier than is usually fired with that twist, but it's stubby and the calculators think it may be OK. I don't know anyone using Varget for light bullets. Being a stick powder it is at least less prone to the secondary pressure issue. But I'd get IMR 4198 or maybe Reloader 10X and just settle for loading that Dogtown bullet down in the 9" twist bore.