5,000 fps .308???
 

Has anyone ever heard of such a thing? I've been watching a "discussion" (more like a pissing contest) between two of your typically anonymous internet "experts" on everything. One of them claims there is some weird "blue .308" that achieves this astonishing 5,000 fps. He says it's a "practice round". Now I feel I keep in touch with developments in the firearms industry, and I have never heard of such a thing. A cursory each didn't turn up anything. I'm thinking this is more than likely some first person shooter game wherein this magic .308 is available, but since I know less than nothing about those, I'm not entirely sure. Any ideas?

I am as far from an expert as you can get.
Your post just made me curious.

It looks like 5000 fps is, hmmm, ambitious, by about 40%ish

repeating what I see in my random sample....

https://www.ammunitiontogo.com/lodge/308-ballistics/
https://aimingexpert.com/what-is-the-muzzle-velocity-of-a-308-round/
https://blog.cheaperthandirt.com/the-fastest-308-win-on-the-market/
https://rifleshooter.com/2014/12/308-winchester-7-62x51mm-nato-barrel-length-versus-velocity-28-to-16-5/

I can't find any such magic bullet.
As with all internet opinions (including a few of yours), I try to respectfully, present my opinion of disagreement along with valid citation of facts if possible and then move on. Is there any reason to belabor the point if you cannot find anything to corroborate their claim?

Mebbe they did it in a vacuum with the wind at their back?

Must be true.... I wrote it on the Internet :D

There is a new round/chambering/design the NATO types are testing right now that uses a two part case with a steel head and they are claiming kaboom levels of pressure and velocity, that may be what he is speaking of.

The other possibility is a "blue pill" - also known as a proof load. Intentionally over loaded to test rifle receiver etc. BUT this process typically ignores velocity and focuses on "some idiot filled a case with super fast pistol powder, will they get a hunk of receiver in their head and die?" type testing instead of ballistics.

Finally... if you cheat and use sabots, a 55gr 223 bullet in a saboted 30-06 round was claimed as good for 4000 fps... you could maybe squeeze a bit more out of it with a 30-378 or something silly like that....

I love that visualization!

Maybe in a particle collider?

I remember Remington produced their Accelerator round decades ago; saboted .223 projectile in both .30-06 and .308. Advertised as (IIRC) ~3800 fps.

I read an interesting analysis about 10 years ago about .223 jacket frangibility at high revs; guy did some FEA and found that 55 gr FMJ (I think) .223 became unstable and jackets failed at about 300K-320K rpm.

5000 fps MV from .308 with 1-12 twist would be ~300K rpm, 1-11 would be ~330K rpm, and 1-10 around 360K rpm. I'd bet you'd need a pretty substantial jacket to avoid disintegration at those rpms; using a super-light projectile (like 35-40 grain, or even something in .17) would have even thinner jackets that I bet wouldn't hold up to the revs. Maybe a super-light solid or sintered projectile?

I wonder what a sabot .308 in a 50 bmg would get you at the muzzle. I doubt 5000 fps but I would believe 4000

5000 fps is in the teritory of main guns of our Abrams and Leopards

OMG, are you serious? I had no idea they were that fast.

Exactly. I love discussions with guys like you who can present knowledgeable, well supported opinions. We can all learn from one another, and have some fun doing so, even if we poke at each other every now and then. It's all in good fun.

This discussion, however, isn't that. I'm not participating, I'm just a spectator. I know better than to get involved when folks like that get going. It just piqued my interest - I had never heard of such a thing. Like I said, I though it was maybe some gaming thing or something. I guess it's not even that, since none of you have hard about this either.


They actually do better than that. The sabot round from the 120mm smoothbore cannon on the Abrams and Leopard exceeds 7,000 fps. Purely a kinetic energy projectile, it has no explosives or anything, no "warhead". Pretty amazing stuff.

Well at our range in Dulzura CA we have the 1000yard shooters come to practice before their matches at Camp Pendelton and the fellow that used to win most of them before he moved to Utah shot custom made 6mm rifles with custom made cases about the size of 50BMG and very long boat tailed bullets. He would never mention what powder he used or other details, but I was watching his chronograph one afternoon and it read 4110 feet per second +/- 0.0002 between shots and that was why he said he used 3 to 4 custom made barrels a year. His barrels were some sort of weird alloy as was the action(s) that he had made for him and the stocks he made out of carbon fiber in molds he made himself. I guess being one of the developers of the Predator drone system helped him with doing some of the technical things and he was super cautious of everything. As an example, he kept his bullet loads in special boxes that were set in foam to protect them from vibrations when driving. The foam was some that is also used to protect Hellfire Missiles during shipping, not sure how or where he got that from?
Anyways 4000FPS was about as fast as a bullet can travel he said when pushed by gun powder.

I had to do a quick edit due to the question below, the fellow I mentioned makes his own bullets, some sort of solid allow he turns on his lathe at home. I know he only shoots at 300 yards and uses some sort of Kevlar fabric behind the target stand that collects his bullets so he can do measurements after shooting.
John

Over 1 mile per second! Yikes. That is awfully fast for something to travel through the atmosphere.

It would be fascinating to see the aerodynamics and stability info.

Note: I know absolutely zero about this sort of thing. I just found the above stat shocking.

I have nothing to add other than my son and I just got back from the range making sure our elk guns were still dialed in (.338 win mag and 30-06).

We also shot some .308 and 5.56, was pretty windy and cold but a good time.

I am not sure how much velocity counts since the World Championship Muzzleloader shoot out to 1000 yards and the velocity on my Pedersoli Gibbs muzzleloader using the same powder load, same wads and same bullet that has won old MR Pedersoli several world championships and I get 1800FPS until my body can't take the shock any longer! I read the specs of those that also have won with other makes of rifles and their velocity is about the same but there are many of those old English and French shooters who say in their interviews "naw...we never care about that....it is how the bullet makes it's hole in the target"!
John

don't know the speeds but those blue rounds are plastic rounds and used for training. they are much faster but weigh next to nothing. will cause some damage but nothing like a regular round. i think they are used because they are much cheaper

Back late in the last century, or maybe early in this one, some brainiacs figured that if you take a x00 pound warhead from a Trident SLBM and simply fill it with concrete, it'll still make one heck of a whack at whatever you hit at Mach 10+.

Cute idea, but maybe a bad choice (I don't think, or know if, we're doing this). It's like a world-scale level of something out of a Dirty Harry movie - Gorsh, was that a nuke or a tactical/kinetic thing that we just launched? In all of the excitement I kind of lost track...

Amusing concept though. I believe we've all reached treaties or at least "gentleman's agreements" that we won't nucularize space - but lobbing 500 pound things at reentry speeds at a moment's notice could be (understatment) amusing.

A polymer 308 (7.62mm) round could get somewhere near 5,000 fps. Regular ball ammo is limited to about 2,700 fps (823 m/s).

- Years ago I read about polymer rounds being used by air marshals. The idea being the polymer round would be far less likely to penetrate the skin of the air craft. They also cause massive tissue damage because of their elevated speed.

I remember reading years ago that Roy Weatherby was working with the gov. during WW2 on a 5000fps round. That was about 20 years ago that I read this, so the outcome and other related info escape me. According to my Sierra reloading manual, 5th edition, page 259. A 22-250 40 gr. Blitzking can be pushed to 4200fps.
This edition was printed in 2003, so maybe newer gunpowder and bullets may get closer to that 5000fps mark. I don't know.

In a past life I used to have to shoot some projectiles that fast. I don’t recall shooting .30cal specifically, but some .223, 9mm, and solid steel frags. We got all of them into that velocity range. I would definitely say it is possible with the right case, sabot, powder, and (most importantly) heavy barrel and action.

I also would never hand fire such a set up.

My question is WHY would you want/need to fire a .308 that fast? Purely for bragging rights?