Posted on 01/18/2017 10:34:50 AM PST by w1n1
In this segment on precision long range shooting conducted by Larry Vicker and spotted by Walt Wilkinson of Gunsite. They will be pushing the range limits on the Lapua 338. Though the video states debunking myths on long range shooting, the results is what is significant.
Larry will be using a 338 Lapua/250 grain bullet with Schmidt&Bender scope, Atlas bipod and with a Armament suppressor. A fact that most long range shooter understands when shooting out to beyond 1000 yards the bullet starts to drop like a rainbow. Thats due to (getting a little technical here) the environmental factors of temperature and barometric pressure. So to overcome this is to run the math in a ballistic app. That’s the reason why they say a grouping at 1500 yards should be at fifteen inches group, where at closer range your groupings could be at 5 inches.
The un-suppressed rifle starts out at 300 yards for zeroing and pushes out to 2500 and outer space to see where the rounds go. For the 338 Lapua with the 20 inch barrel the drop off point was at 1470 yard. The bullet is tumbling, yawing, spinning out of control and would land in a group size of a Volkswagen.
From here its back to the 1313 yards where the gun was in the zone with a suppressor attached. Suppressed Lapua had no problem hitting steel targets at 1313 and 1470 yards, but lost it at 1583 yards.
Discoveries Un-Suppressed with a 338 Lapua
A 250gr bullet in .338 does not have sufficient sectional density to stay true over that distance.
A 300gr boat tail would do the trick. The BC must be at least .6
Very interesting!
I have two .340 Weatherby Magnums that are very close to the .338 Lapua ballistically. Just at 200 yards by removing the recoil suppressor I will be about 2-1/2 to 3” high on my grouping, for both of them shooting 250 Gr. Nosler bullets.
“A 250gr bullet in .338 does not have sufficient sectional density to stay true over that distance.
A 300gr boat tail would do the trick. The BC must be at least .6”
Ditto. Some think long range shooting is all about velocity when in truth it is more about ballistic coefficient.
Somebody needs to make a 325gr .338 spitzer.
Nosler tops out at 250.
It would have sufficient sectional density and therefore stability to shoot that distance.
Not there’s many reasons to shoot that distance. Even on a bench your heartbeat will move the reticule 5 feet.
I highly doubt that a suppressor gives any bullet more velocity.
What I would believe is that a suppressor retains much of the muzzle blast as the bullet exits, so the bullet is less disturbed as it leaves the muzzle.
I wondered about that velocity claim as well, but your idea here has merit. Air gun shooters have been fiddling with "airstrippers" on the muzzle for some time for similar reasons. No idea if they work or not.
Hitting man sized targets out to a quarter mile is not difficult. After that it takes high quality components and highly trained shooters.
“A 250gr bullet in .338 does not have sufficient sectional density to stay true over that distance.
A 300gr boat tail would do the trick. The BC must be at least .6”
They shouldn’t have been shooting a Sierra bullet at all. First of all, the Lapua 250-gr lockbase bullet is the gold standard in that weight class (the same bullet Cpl Harrison used for his 2707-yard shots [plural] in Afghanistan) because it isn’t unsettled by the transonic transition. Harrison’s bullet was down to ~800 fps at impact, so transonic stability was crucial.
Second, Berger Bullets’ chief ballistician, Bryan Litz, is blazing new trails in bullet design and long-range precision shooting. Civilian hobbyist shooters all over the fruited plain are scoring hits at incredible ranges with Litz-designed Berger Bullets. Many of them use 1500 yards for a warm-up. His .338 big hitter is a 300-grain hybrid design (ogive is part tangent, part secant) with a (claimed) G1 BC of 0.822.
To: Yo-Yo
“I highly doubt that a suppressor gives any bullet more velocity.
What I would believe is that a suppressor retains much of the muzzle blast as the bullet exits, so the bullet is less disturbed as it leaves the muzzle.”
It does add a small bit, a few fps. It’s called “freebore boost.” And you’re right, the bullet exiting the muzzle is less disturbed/more accurate to boot.
A Volkswagen Bug....or a van?
A 250gr .338 bullet is just not long enough to maintain stability of those distances. As you said, once it drops below the sound barrier in velocity, it wobbles off course.
Here’s a new one at .72.
It would be my choice for distance in any .338 or .340 mag.
Won’t be long when LASER weapons will put lead bullets in the antique shop.Set to stun or kill like Star Trek.Travel at speed of light also.
“A 250gr .338 bullet is just not long enough to maintain stability of those distances. As you said, once it drops below the sound barrier in velocity, it wobbles off course.”
You apparently failed to read my entire post. The Lapua 250-gr lockbase bullet is unperturbed by transonic transition. Corporal of Horse Craig Harrison’s 2707-yard shots — using the 250-gr lockbase — were ~300 fps below the speed of sound on impact. And he was using an identical rifle to the one Vickers and Wilkinson were shooting in the linked article. So, no, the 250-grain bullet IS NOT too short for transonic stability.
And according to Bryan Litz, length is not controlling of transonic stability. Litz (of Berger Bullets) is (was) an honest-to-goodness rocket scientist, formerly a rocket design engineer for the US Air Force.
I don’t know where he ranks among the world’s living ballisticians but I will tell you without fear of contradiction that he’s the best one on the planet who routinely schmoozes with us common schlubs on the Internet. He maintains a presence in several shooting forums and gladly answers any reasonably intelligent question from the peanut gallery. And thank god he does because he manifestly has increased the body of fact-based ballistics knowledge available to Joe Sixpack. His first book, Applied Ballistics for Long Range Shooting, belongs in every serious shooter’s bookcase. Best of all, it’s written so simply that a reasonably intelligent sixth-grader could understand it.
Anyway, Litz’s research shows that boattail length and angle are the key factors in transonic stability. Not bullet length. Which isn’t to say bullet length and BC aren’t connected, which they obviously are. But that’s a separate issue from transonic stability.
FWIW I checked the specs on the Accuracy International AX in .338 Lapua (same rifle as the British Army’s L115A3) and the factory barrel has a 1:11 twist. Berger and Sierra both recommend at least a 1:10 for their 300-gr .338 bullets. So the mystery of why Vickers and Wilkinson only were shooting 250-grain bullets is solved. Stability from the 1:11 barrel they were shooting would have been shaky at best.
Thank you for the edifying comments.
I now understand why they limited themselves to 250gr.
Of course the 2707yrd shots may have reached their target supersonic if he could have used the Nosler 300gr with a .72 BC.
And yes, those long bullets need to spin.
Kreiger will cut you a barrel of any weight, caliber or twist rate and then cryogenically treat it for temperature stability at first shot.
Gee, do you think gravity might have anything to do with it?
Who writes things this stupid?
Lasers can be affected by atmospheric conditions. And mirrors. Further they could just be blinding weapons, youd never even see the beams because they are in the infrared spectrum.
What’s the BC on lasers?
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