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9/19/2017 7:27:10 PM
Posted: 2/21/2006 6:29:41 PM EDT
Hi,
I am looking to build a rifle with a 16" barrel with a 1:7 twist rate. I would like to experiment with the heavier bullets out there (70+ grains, etc) and hence looking at the 1:7 rate to better stabilize them. My question to the board is I also want to shoot plinking ammo, like Wolf 55 gr. but am wondering if this ammo would "fly apart" with the high rotational velocity. Below is what I could find from Ammo-Oracle.

"You can also spin them so hard they fly apart. That's rare, but it happens if you are dealing with very tight twists and very high velocities. When fired at 3200 fps in a 1-in-7 twist rifle, a round is rotating at over 300,000 rpm when it leaves the muzzle. Light, thin-jacketed varmint bullets (i.e., 40gr Hornady TNT or Federal Blitz bullets) often can't take that much spin and will pull themselves apart."

They don't comment specifically on 55 gr Wolf....you folks have any experience with it in a 1:7 twist 16" barrel??? I wonder if 55 gr Wolf has a thin Jacket???

Also, another question about the heavier bullets (70+ grains) do they need to fragment to work for lethality or is it the mass that is causing lethality. In other words, do I need high velocity to get lethality from the heavier bullets? Since I am looking at a 16" carbine, velocity at 100 yds and on will be an issue....thanks...

Thanks,
cpy911
Link Posted: 2/21/2006 8:37:53 PM EDT
[Last Edit: 2/21/2006 8:50:13 PM EDT by Dont-Tread-On-Me]
#1: 55gr bullets aren't light enough to blow apart from a 1/7 twist. In fact, a lot of shooters get away with 45gr bullets, but I wouldn't shoot those. Whole purpose of a 1/7 is so you can shoot the good stuff *cough Hornady 75's cough*. I'm sure a 35-45gr bullet would probably fly apart. Tiny bullets moving at 3,700+ fps in a corkscrew tight twist like a 1/7 just aren't meant for eachother. Aside from the massive centrifugal force placed on the bullet, I'd have to imagine that the bullet's jacked is being damaged trying to "stay on track" with the rifling.


#2: Wolf is weakly loaded, in other words - SLOW. Wolf doesn't break the 3,000fps barrier- period. At least not in my barrel, being measured with my chrono.


#3: Wolf ammo is notorious for having a very THICK and STRONG jacket. One that is absolutely useless for fragmenting. I'll make a guess and say this might help it stay together even better from a 1/7 barrel. But that is moot, since 1/7's don't blow up 55 grainers anyway.


I think you'd be good to go with Wolf. I have two 1/7's. A 16" and a 20". I shoot Wolf with no problems. Since the price was the same, I chose the 62gr Wolf. But I've used 55gr.


Also, another question about the heavier bullets (70+ grains) do they need to fragment to work for lethality or is it the mass that is causing lethality. In other words, do I need high velocity to get lethality from the heavier bullets? Since I am looking at a 16" carbine, velocity at 100 yds and on will be an issue....thanks...



The heavy bullets have almost a whole new advantage factor. As .223 bullets increase in weight, they can only do so in length, as width is obviously a constant (has to fit the bore) As a result, heavier bullets are obviously much longer. Longer bullets need more RPM's to stabilize, this is why everyone's after the 1/7's. The heavy bullets, in addition to being long, are also somewhat of a hollow point design. Called "open tip match". The hollow point isn't designed to expand, it is there for accuracy. Also, these bullets, due to their shape and length, as well as having an empty cavity at the tip are very butt heavy. Combine length and mass at the rear, and these heavy .223's yaw violently and quickly. Just like, nope, even better than the Russian 5.45x39mm. The heavy .223's begin to yaw (tumble) very early after entering tissue. This obviously caused a much more traumatic wound. To make matters worse (or better depending on your point of view) they fragment violently.


You don't need higher velocity to get the heavy bullets to fragment. Any heavy bullet, loaded even to .223 saami specs (not hot NATO loads) will still have enough velocity at 100 yards to reliably fragment. The higher velocity just extends the range at which they will reliably fragment. Also, due to the design of the heavy bullets, their fragmentation range is greater than that of ligher bullets such as the 55gr. No matter what, a 75gr/77gr loading will outperform a 55gr loading regardless of range. Better destruction of tissue, and increased fragmentation range.



Link Posted: 2/21/2006 8:46:54 PM EDT

Originally Posted By cpy911:
....Also, another question about the heavier bullets (70+ grains) do they need to fragment to work for lethality or is it the mass that is causing lethality. .



No bullet needs fragmentation or expansion to acheive lethality. They need proper placement, and enough penetration to hit the CNS or major blood carrying organ/vessel.

Fragmentation just enhances the dammage caused by the relatively small bullet, and the enhanced dammage can cause the Goblin to bleed out faster. The faster they bleed out the quicker the blood pressure drops - the quicker the blood pressure drops the faster they are taken out of the fight.

Different rounds require different velocities to acheive fragmentation. Also different rounds fragment at different depths. In general the heavy OTMS fragment at much lower velocities than the military FMJs. Which bullet specifically do you have in mind?
Link Posted: 2/22/2006 8:56:22 AM EDT

Originally Posted By cpy911:
like Wolf 55 gr. but am wondering if this ammo would "fly apart" with the high rotational velocity. Below is what I could find from Ammo-Oracle.





DO NOT USE "thin skin" varmit bullets at high speed, they can/do fly apart.. I read about it back in 1989-1990 American Rifleman article, so I just had to try it in my 20" 1x7 COLT barrel.

Manuals say you can get away with it, as long as velocity is held in the 2900-3000 fps range.

I just loaded some up, and when fired, about 75yd down range you would hear a "pop" and see a puff of blue smoke.... Somebody want to send a couple different Hornady V-Max bullets for me to load and test out of the 1x7 barrel ?
Link Posted: 2/22/2006 9:27:20 AM EDT
Well, that's even worse. Shooting light-highspeed varmint bullets in a 20" 1/7 will put a LOT more spin on the bullet than a 16" 1/7 will. Remember, the longer barrel will allow the bullet to reach greater velocities while inside the barrel. Faster the bullet runs through the rifling, the greater the spin imparted on the bullet.


That's why 24" 1-9's stabilize 75gr bullets without any problem, while 16" barrels are very ify.


How far away did the bullet fly apart in your best estimation? I'm guessing that if the SHTF, and all you could get were 45gr Winchester from Wal*Mart, that would probably still work under 15yards for home defense.
Link Posted: 2/22/2006 11:07:28 AM EDT
Wolf makes damn good ammo now well sorta SEBIA M193
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