Aerospike 300 BLK 146 Lulu adventure begins

[dellet]

So theoretically one might be able to stay supersonic longer with a smaller capacity case verses having to step on the gas with a larger case cartridge to stay supersonic at extended range? That is aerospike vs standard BT in the same case.

That’s my understanding. The exact answer I received to the question of 40% gain, “was energy retained farther” the only way to retain energy is to retain velocity.

This is one of the language barriers that is causing friction.

Case capacity shouldn’t matter, but there is a velocity window where it works. Basically turns on for a simple explanation.

 

[HappyHellfire]

So theoretically one might be able to stay supersonic longer with a smaller capacity case verses having to step on the gas with a larger case cartridge to stay supersonic at extended range? That is aerospike vs standard BT in the same case.

The "ideal" bullet would completely ignore air resistance. The lower the drag coefficient, the closer any bullet is to that "ideal". In reality, we will probably never get to a perfect "vacuum" bullet.

So yes, the idea is that the lower drag causes a flatter trajectory, better retained energy, less wind error, and increased range. In reality, with the aerospike only engaging at it's design point of Mach 1.4-1.6, it flies like a regular bullet above that. If you shoot a bullet in that range it just has much lower drag. That is why I started with the 300 blackout. It is fired at the idea muzzle velocity and has a high enough twist that the aerospike should really show it's worth right from the barrel.



What is being tested here is if they can also be fired with extreme accuracy that is wanted by the shooters on this forum.

 

[TTE]

What is being tested here is if they can also be fired with extreme accuracy that is wanted by the shooters on this forum.

"Only accurate rifles are interesting"

 

[davidjoe]

Happy, in my opinion, offering benefits of performance at long range is the ripe market. 1,000 yards and beyond. It also seems to be the threshold where your design sees a benefit.

Accuracy is king, as said, and the best example I can think of, where a bullet defeats sheer power, but is very challenged to shoot a smaller group, is demonstrated by the RSAUM shooting Berger 180 hybrids, versus the .308 shooting 250 A-Tips.

If I punched in the numbers correctly, these two drift exactly 5.3 moa in a 10 mph crosswind at 1,000 yards if the saum hits 2,975 fps MV and the .308 is fired at 2,400, and yes, these are both perfectly attainable velocities.

Punch in drift for 2,000 yards and the .308 is 21 inches INSIDE the SAUM, and the gap, of course, only gets greater with distance. Hence my “unfailing” affinity for that bullet.

Look at those two cartridges. It “should” be inconceivable that ANY .308 and the magnum saum would require the same wind hold. The 180 hybrid is an efficient bullet after all.

This particular .308 is an experiment of mine to create the most solidly built, non-resonant, self-contained long range .308 possible, under a weight.

It does prove difficult for the heaviest bullets for caliber to group smaller, in MOST range conditions. Why that is may not be fully known, but we see it across disciplines. This disparity could perhaps be chipped away.

 

[dellet]

Accuracy is king, as said, and the best example I can think of this, where a bullet defeats sheer power, but is very challenged to shoot a smaller group, is demonstrated by the RSAUM shooting Berger 180 hybrids, and the .308 shooting 250 A-Tips.

It’s worth pointing out that Hornady goes above and beyond to deliver a consistent bullet with the A-Tip, quality control is taken very seriously. Individually wrapped in an egg carton style box, delivering them without cleaning.

Reason for not cleaning at the factory is the only cost effective way would be to tumble. Tumbling would introduce imperfections.

Those imperfections, induce a certain amount of wobble, which in the case of the Aerospike, tend to negate the gain of the spike.

 

[LVLAaron]

Happy, in my opinion, offering benefits of performance at long range is the ripe market. 1,000 yards and beyond. It also seems to be the threshold where your design sees a benefit.

Accuracy is king, as said, and the best example I can think of this, where a bullet defeats sheer power, but is very challenged to shoot a smaller group, is demonstrated by the RSAUM shooting Berger 180 hybrids, and the .308 shooting 250 A-Tips.

If I punched in the numbers correctly, these two drift exactly 5.3 moa in a 10 mph crosswind at 1,000 yards if the saum hits 2,975 fps MV and the .308 is fired at 2,400, and yes, these are both perfectly attainable velocities.

Punch in drift for 2,000 yards and the .308 is 21 inches INSIDE the SAUM, and the gap, of course, only gets greater with distance. Hence my “unfailing” affinity for that bullet.

Look at those two cartridges. It “should” be inconceivable that ANY .308 and the magnum saum would require the same wind hold. The 180 hybrid is an efficient bullet after all.

This particular .308 is an experiment of mine to create the most solidly built, non-resonant, self-contained long range .308 possible under a weight.

It does prove difficult for the heaviest bullets for caliber to group smaller, in MOST range conditions. Why that is may not be fully known, but we see it across disciplines. This disparity could perhaps be chipped away.

Deets to make that bullet work in a 308? 8.5 twist, bullseye powder, and a 2 inch freebore?

 

[Mike Casselton]

I suggest trying Snipers Hide.

Yes please.
And please make the first post in the Bear Pit.

 

[HappyHellfire]

Deets to make that bullet work in a 308? 8.5 twist, bullseye powder, and a 2 inch freebore?

I have a Win 308 stable bullet now. The aerospike is not as aggressive as the 300 blackout but it is stable with a 1:10 twist and with my bullet characterization testing it looks pretty good. I have two people testing them in the near future.

 

[davidjoe]

^^ Use a Unithroater, a little at a time, to find touch, where Lapua Palma brass can hold (compressed) between 47.0 and 47.5 of H4350, without creating much seating stem ring on the nose. The way I generally do that is press them partially in, wait a while, and come back to seat them to final depth, as that lets the powder start to sort itself out. If needed tap the rim on a soft pine block. It’s probably technically possible to take the bore rider idea all the way to the point of not needing to pass the donut, but I don’t go that far with it, and I’ve still managed to get 48.0 grains in and max MV of about 2,450.

An 8.5 twist might very well work, and it does in my 300 Win Mags for 250’s. That is the box specification. My .308 barrels are 8 twists, so I do know that it works at sea level for them.

The difference between a 300 Win Mag and a .308 is usually about a 400 yard handicap to the .308, after which point the bullets are in theory behaving the same way. But that would imply to me that if an 8.5 works for a 300 WM all the way out to steep angle impact miles away, then it will for a .308 as well.

The great thing about the .308 is that in it, not a single 250 has had a rapid unscheduled disassembly. That has been a problem for me with the Win Mags.

** Happy, — solids are immune to that, like Daniel in the lions den. Also, there’s the little matter of a possible needle nose. We really go to great lengths to trim and repoint those BTHP’s for long range, it’s definitely not the case that we think looking into a gaping irregular hole is ideal. **

 

[dellet]

Short statement, here’s a 5 shot group
Long statement details/excuses
75 yards, best I can do until the range opens back up.
Remington 700, XLR Evolution chassis 24” Bartlien 1/10
18 grains 296
2.175” COL
.100” Bearing surface in neck.
Avg Velocity 2120 fps ES 59 SD 18.6
Group includes cold clean bore
Front rest, round handgaurd
Buttstock AR type
,910 outside to outside,



Yes, I have a photo of the 3 marked shots time stamped yesterday If I need it.

With a proper(even decent) setup I’m sure I can cut that group in half.
I need an adapter plate for the front any suggestions appreciated.

Now the bad part. More issues sorting and loading.



You can see a definite line where the tail transitions to the bearing surface. That’s actually a lip or step. Takes about 50 pounds to force the bullet into the neck, with a distinct pop. Using an arbor press, it’s a clear problem. Probably need to drag out the dreaded concentricity gauge and see if it’s a problem. I hate to bell the case neck, shouldn’t need that.

Still problems measuring the bearing surface. Used cases opened up with a .309” mandrel. .307” pin is lose, .308 won’t go. Yes, it’s farm engineering, might be off a few thousandths. Case length 1.364, bearing surface length .2156”. Caliper should read 2.944” or something reasonably close. Three different bullets.








I need to establish a base line velocity in one more rifle with a 1/7. Then match those velocities with two other bullets. Then the actual testing will begin.

I hope to get at least another 100 fps in the 1/10 twist, the long tail will
Make that difficult, but we’ll see.

I actually think there is hope for the bullet, but there is some basic production work that needs to be done. Time will tell.

 

[wwbrown]

Maybe john should reach out to a machinist with significant CNC lathe experience to help him out on the prototype machining. When I ask help from skilled folk on something trivial in their area but where I am clueless I call it "Adult Supervision" which I think we all may need at times.

(imagine this is a faceplant emoji) I forgot that the machinist trained through their possibly decades of experience and accomplishments. Since the machinist might not have a PhD john would give no value to the advice given ... total waste of time.

 

[Ccrider]

Maybe john should reach out to a machinist with significant CNC lathe experience to help him out on the prototype machining. When I ask help from skilled folk on something trivial in their area but where I am clueless I call it "Adult Supervision" which I think we all may need at times.

(imagine this is a faceplant emoji) I forgot that the machinist trained through their possibly decades of experience and accomplishments. Since the machinist might not have a PhD john would give no value to the advice given ... total waste of time.

Why don’t you guys give it a break.

 

[JLT]

Short statement, here’s a 5 shot group
Long statement details/excuses
75 yards, best I can do until the range opens back up.
Remington 700, XLR Evolution chassis 24” Bartlien 1/10
18 grains 296
2.175” COL
.100” Bearing surface in neck.
Avg Velocity 2120 fps ES 59 SD 18.6
Group includes cold clean bore
Front rest, round handgaurd
Buttstock AR type
,910 outside to outside,

View attachment 1576352

Yes, I have a photo of the 3 marked shots time stamped yesterday If I need it.

With a proper(even decent) setup I’m sure I can cut that group in half.
I need an adapter plate for the front any suggestions appreciated.

Now the bad part. More issues sorting and loading.

View attachment 1576353

You can see a definite line where the tail transitions to the bearing surface. That’s actually a lip or step. Takes about 50 pounds to force the bullet into the neck, with a distinct pop. Using an arbor press, it’s a clear problem. Probably need to drag out the dreaded concentricity gauge and see if it’s a problem. I hate to bell the case neck, shouldn’t need that.

Still problems measuring the bearing surface. Used cases opened up with a .309” mandrel. .307” pin is lose, .308 won’t go. Yes, it’s farm engineering, might be off a few thousandths. Case length 1.364, bearing surface length .2156”. Caliper should read 2.944” or something reasonably close. Three different bullets.

View attachment 1576354


View attachment 1576355

View attachment 1576356

I need to establish a base line velocity in one more rifle with a 1/7. Then match those velocities with two other bullets. Then the actual testing will begin.

I hope to get at least another 100 fps in the 1/10 twist, the long tail will
Make that difficult, but we’ll see.

I actually think there is hope for the bullet, but there is some basic production work that needs to be done. Time will tell.

Describe your handguard a bit. I have a three-inch plate that should work, depending on the handguard diameter. From what I recall, the Evolution chassis/handguard is M-Lok compatible. If the direct-mount plate I have won't work, I have a fairly good-sized pile of stuff that might work, and I'd be happy to send it to you. It may have to wait for a couple of weeks, though. I'm getting on an early flight tomorrow for a two-week (dare I say it?) academic conference in Budapest.

 

[ronemus]

I have a Win 308 stable bullet now. The aerospike is not as aggressive as the 300 blackout but it is stable with a 1:10 twist and with my bullet characterization testing it looks pretty good. I have two people testing them in the near future.

View attachment 1576299

The problem I see is the limited velocity range over which the aerospike has an advantage. The vast majority of target shooting is done at velocities at or above Mach 1.2, largely due to instabilities in the trans-sonic region. If the aerospike is more stable through the trans-sonic regime than conventional designs, that is significant in and of itself and would have some interesting applications. Hunting, police and and military applications (except specialty units such as special forces, sniper/SWAT,etc.) don''t even run that slow. Unless you have some advantage at higher velocities than you have discussed, I don't see the benefit. You should really be comparing your design to copper monolithic VLD boattail designs, which anybody who might consider your bullets would be comparing them to. None of this is criticism, but what you have shown to date leaves me wanting a lot more information. I assume this is also the case for my compatriots.

 

[dryhumor]

@dellet
My Sinclair tool base has steps and a recess for measuring cases. The recess could accommodate the spike. If you had a similar arrangement, your measurements might be more consistent. All depends on the diameter of the step opening to the diameter of the bullet base. Wouldn’t be too difficult to make from scratch.

 

[dellet]

@dellet
My Sinclair tool base has steps and a recess for measuring cases. The recess could accommodate the spike. If you had a similar arrangement, your measurements might be more consistent. All depends on the diameter of the step opening to the diameter of the bullet base. Wouldn’t be too difficult to make from scratch.
View attachment 1576414

I just drilled a hole in a Hornady anvil to accommodate the spike for overall length and base to ogive.

For comparator bodies I used shortened 38 special brass through a 30 Luger die. Made the whole thing easier to handle, gave a nice large diameter base for stability and the results were about the same.

Measured some Berger bullets since they publish all their specs and my measurements were a lot closer, within a few thousands, but more consistent. Berger flat out tells you that lot to lot will differ, but they should be consistent bullet to bullet.

 

[HappyHellfire]

The problem I see is the limited velocity range over which the aerospike has an advantage. The vast majority of target shooting is done at velocities at or above Mach 1.2, largely due to instabilities in the trans-sonic region. If the aerospike is more stable through the trans-sonic regime than conventional designs, that is significant in and of itself and would have some interesting applications. Hunting, police and and military applications (except specialty units such as special forces, sniper/SWAT,etc.) don''t even run that slow. Unless you have some advantage at higher velocities than you have discussed, I don't see the benefit. You should really be comparing your design to copper monolithic VLD boattail designs, which anybody who might consider your bullets would be comparing them to. None of this is criticism, but what you have shown to date leaves me wanting a lot more information. I assume this is also the case for my compatriots.

The design of the aerospike can be varied to where it engages. All of my current designs engage at Mach 1.4 to 1.6. I can get them up to Mach 2.2 but it is difficult to stabilize them as the tail gets longer. Plenty of growth for the future I think

As for transonic stability they "appear" to be transonic stable. I hope to have a test this year that proves it by shooting at full speed (Mach 2.4-3) and then inspecting holes at impact under Mach 1. If they stay round and I can confirm impact velocity that would be pretty good proof of transonic stability.

I have been chasing data on these things for the last five years. I know how you feel.

 

[dellet]

The design of the aerospike can be varied to where it engages. All of my current designs engage at Mach 1.4 to 1.6. I can get them up to Mach 2.2 but it is difficult to stabilize them as the tail gets longer. Plenty of growth for the future I think

As for transonic stability they "appear" to be transonic stable. I hope to have a test this year that proves it by shooting at full speed (Mach 2.4-3) and then inspecting holes at impact under Mach 1. If they stay round and I can confirm impact velocity that would be pretty good proof of transonic stability.

I have been chasing data on these things for the last five years. I know how you feel.

Round holes or not, won’t tell you the whole story at distance or transonic flight. Angle of entry can fool you.

What generally happens long before oblong holes is that the group opens up. Example shooting 1 MOA groups every 100 yard intervals then all of a sudden you cross into trans sonic speed and it’s 2 MOA and growing.

You notice this shooting so called sub sonic, it’s really trans. With a lot of bullets they are much more accurate under 1000 fps than over. Light bullets, as in air guns in particular.

 

[HappyHellfire]

Round holes or not, won’t tell you the whole story at distance or transonic flight. Angle of entry can fool you.

What generally happens long before oblong holes is that the group opens up. Example shooting 1 MOA groups every 100 yard intervals then all of a sudden you cross into trans sonic speed and it’s 2 MOA and growing.

You notice this shooting so called sub sonic, it’s really trans. With a lot of bullets they are much more accurate under 1000 fps than over. Light bullets, as in air guns in particular.

I hear you. One of the tricks we used to use was to stack cards with a fixed distance between them (stacked yaw cards). Then as the bullet flies through them we could estimate the frequency and amount of wobble. For small wobble it is really not that useful. A high speed camera would be better but I don't have the 250K for one.

 

[ronemus]

I hear you. One of the tricks we used to use was to stack cards with a fixed distance between them (stacked yaw cards). Then as the bullet flies through them we could estimate the frequency and amount of wobble. For small wobble it is really not that useful. A high speed camera would be better but I don't have the 250K for one.

Much easier to shoot groups - they will open up long before there is yaw detectable by cards or cameras.