Aerospike 300 BLK 146 Lulu adventure begins

[dellet]

Now if I remember correctly you had to trim necks back .020 shorter to get enough of the bullets bearing surface in the neck.
Do you think a different reamer spec is in order, or possibly something that can be overcome with more bullet refinement?
Carbon ring worries with the shorter case of any concern?
Just a couple thoughts

I think I was referring to the 250 A Tip to trim the neck back so I could load them the magazine length, 2.260”. Just a party trick to say I shot them from on AR. I load them for the bolt action at 2.485”, just touching.

This bullet is the opposite. A very short bearing surface, placed far forward. Depending on trim length, there will be .060”-.080” of gap between the end of the case and bearing surface when the bullet hits the lands. A bunch of photos in the first post, but here’s what it will look like.
Jump will be in the neighborhood of .200”+ with the bullet free floating out of the case. I think a carbon ring is certain. Just when, not if.

This bullet might actually work better in a Wilson 7.62X40 (5mm longer). The nose is probably to long.for a 300 Ham’r. Just need to rechamber a blackout barrel or order a custom to get the faster twist.

 

[Oso]

The challenge for the 300 HAM'R is its case length, which limits the types/profiles of 30cal bullets that can fit within magazine length. The case length on the 7.62x40 WT is approx. .040" shorter than the 300 HAM'R... so a little for room for testing.

What you really need is a bolt rifle chambered in either cartridge so that you can have extra case length for seating the bullet's bearing surface without running into the 2.26" magazine length restriction.

 

[dellet]

The challenge for the 300 HAM'R is its case length, which limits the types/profiles of 30cal bullets that can fit within magazine length. The case length on the 7.62x40 WT is approx. .040" shorter than the 300 HAM'R... so a little for room for testing.

What you really need is a bolt rifle chambered in either cartridge so that you can have extra case length for seating the bullet's bearing surface without running into the 2.26" magazine length restriction.

I’m pretty sure I could make it work in a 300 Ham’r buy using an HK magazine, loaded to 2,300”

There are a couple others out there now with larger internal for the heavier bullets. They have to be all steel.

7.62X40 would be easier.

Both would still have a looong jump and not much room to tune with seating depth.

First prove the bullet.

 

[ronemus]

I’m pretty sure I could make it work in a 300 Ham’r buy using an HK magazine, loaded to 2,300”

There were magazines for the AR-15 developed by Long Range Products and taken over by DPMS that load a single stack with the case heads in the rib. They allow loading to 2.48" for the magazine; a great way to free up room for powder with heavies. I run them in my XTC spacegun. Unfortunately they've been out of production for at least 15 years. Those of us that have them tend to hang onto them for dear life, but some might appear at estate sales. Maybe that idea will come around again.

 

[ronemus]

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.

This could be explored in .223 Remington - lots of length to accommodate the tail. We'd probably have to use an arbor die upside down to avoid crushing the powder too much. Most target competitors are running a 1:7 twist, or a 1:6.5 for the 90 gr bullets. Would your aerospike designs need a faster twist than that

 

[Bc'z]

There were magazines for the AR-15 developed by Long Range Products and taken over by DPMS that load a single stack with the case heads in the rib. They allow loading to 2.48" for the magazine; a great way to free up room for powder with heavies. I run them in my XTC spacegun. Unfortunately they've been out of production for at least 15 years. Those of us that have them tend to hang onto them for dear life, but some might appear at estate sales. Maybe that idea will come around again.

You could window the front of a steel 5-10 round mag.

 

[ronemus]

That only gets you to 2.270".

 

[Bc'z]

That only gets you to 2.270".

6x45 with 80gr Barts Dominator with no feeding issues.

 

[jelenko]

That only gets you to 2.270".

PRI mags with no window go to 2.300. I've been loading my rounds with N135/140 to 2.290 so I can get enough powder in with a Dillon.
With a window they go to 2.36.

 

[HappyHellfire]

This could be explored in .223 Remington - lots of length to accommodate the tail. We'd probably have to use an arbor die upside down to avoid crushing the powder too much. Most target competitors are running a 1:7 twist, or a 1:6.5 for the 90 gr bullets. Would your aerospike designs need a faster twist than that

I played with a .223/5.56 aerospike design and nearly killed myself when the AR platform I was using exploded. Now I only use bolt or break barrel rifles for testing and I have a hard time finding a bolt action 1:7 5.56. This is one of the reasons I won't send out prototype designs. I have to shoot them myself until I feel comfortable releasing them into the wild.

I just ordered a universal receiver that will enable me to test different cartridges at a variety of twist rates. It should make my testing faster, safer, and give better data. I understand that they are also used for ultra accuracy testing. I might be able to do some accuracy testing of my own.



That said, the data on the 5.56 aerospike does look good so far. I think I can really extend the range of the M4 with my bullet.

 

[ronemus]

Glad to hear of the progress!

 

[dellet]

I played with a .223/5.56 aerospike design and nearly killed myself when the AR platform I was using exploded. Now I only use bolt or break barrel rifles for testing and I have a hard time finding a bolt action 1:7 5.56. This is one of the reasons I won't send out prototype designs. I have to shoot them myself until I feel comfortable releasing them into the wild.

This is a bit troubling. Good that it was not tragic, and that you value safety, but the pressure needed to destroy an AR, is extreme. Your weakness in internal Ballistics has shown through out all these threads, and I pointed out earlier that that the data you included with the bullets was incomplete, and would get someone hurt. I had no idea there had already been a near miss.

Using a bolt action for testing, is a good idea, it will help cover up for a certain amount of loading errors, but the pressure needed to explode an AR, is not a simple loading error. It’s a catastrophic error in judgement, or sloppy quality control.

I speak from experience.

 

[Kracken McGraw]

I played with a .223/5.56 aerospike design and nearly killed myself when the AR platform I was using exploded. Now I only use bolt or break barrel rifles for testing and I have a hard time finding a bolt action 1:7 5.56. This is one of the reasons I won't send out prototype designs. I have to shoot them myself until I feel comfortable releasing them into the wild.

I just ordered a universal receiver that will enable me to test different cartridges at a variety of twist rates. It should make my testing faster, safer, and give better data. I understand that they are also used for ultra accuracy testing. I might be able to do some accuracy testing of my own.

View attachment 1577184

That said, the data on the 5.56 aerospike does look good so far. I think I can really extend the range of the M4 with my bullet.

So I take these in the pic aren’t yours?

 

[HappyHellfire]

So I take these in the pic aren’t yours?

Nope, I just got the quote and put in the order. It's like a 3 month lead time.

In addition, I have to get approval from the university to spend grant money on it. Do you know how hard it is to convince academics that I need to buy guns for research? I got the cops called on me and had the university president called on a Sunday afternoon after a "safety inspection" of my lab found reloading equipment. They are almost as hostile toward my research as some of the people on here!

 

[HappyHellfire]

This is a bit troubling. Good that it was not tragic, and that you value safety, but the pressure needed to destroy an AR, is extreme. Your weakness in internal Ballistics has shown through out all these threads, and I pointed out earlier that that the data you included with the bullets was incomplete, and would get someone hurt. I had no idea there had already been a near miss.

Using a bolt action for testing, is a good idea, it will help cover up for a certain amount of loading errors, but the pressure needed to explode an AR, is not a simple loading error. It’s a catastrophic error in judgement, or sloppy quality control.

I speak from experience.

It wasn't the bullet. How do you collect data on a 5.56 at Mach 1.2? Most internal ballistic calculators won't work at that slow a speed with a case fill of less than 85%, at least they didn't last time I used them. I have to develop my own internal ballistic models and then use a bunch of tricks I learned at Dahlgren to force the gun to shoot the bullet well outside of what it was intended. If you get the math just a bit wrong you can get extreme pressure spikes.

The universal receiver barrels will have pressure ports for testing along the barrel. Again, much safer.

 

[davidjoe]

Nope, I just got the quote and put in the order. It's like a 3 month lead time.

In addition, I have to get approval from the university to spend grant money on it. Do you know how hard it is to convince academics that I need to buy guns for research? I got the cops called on me and had the university president called on a Sunday afternoon after a "safety inspection" of my lab found reloading equipment. They are almost as hostile toward my research as some of the people on here!

Happy, since you brought this subject up, and you may have already, but do take a close look at what things a person can produce for use by others, before the person may need to took at obtaining licenses/permits.

 

[dellet]

It wasn't the bullet. How do you collect data on a 5.56 at Mach 1.2? Most internal ballistic calculators won't work at that slow a speed with a case fill of less than 85%, at least they didn't last time I used them. I have to develop my own internal ballistic models and then use a bunch of tricks I learned at Dahlgren to force the gun to shoot the bullet well outside of what it was intended. If you get the math just a bit wrong you can get extreme pressure spikes.

The universal receiver barrels will have pressure ports for testing along the barrel. Again, much safer.

The short answer is simply shoot it at that velocity. I do that all the time. When I’m testing the expansion velocity window of a bullet, I’m never more than 20 yards from the test material and the chronograph is set at the target so exact impact velocity is recorded, not estimated. This requires around a 1500 fps window of velocity. It might require several different powders. Slowest loads I’ve ever done for 300 BLK were 550fps. From a 16” barrel.

Something like quickload as a purchased product is the easy answer. Gordon’s reloading tool is a free version that is very similar. sommeone starting out loading, and immediately going to outside of the box loads would likely be better off with Quickload. Currently (unless things have changed in the last year) more powder and bullet profiles. I have been using quickload for probably 15 years, it wasn’t new on the market then. Not sure when you blew up your rifle, but the source was likely available.



It’s how guys shooting $20,000 150 year old Blackpowder rifles using smokeless powder keep from blowing up rifles only good for 30,000 psi.

Look at cast bullet loads for powders. 13-1500 fps loads for a 223 will be plentiful.

For both of the above examples safe loads of less than 50% density will be common.

 

[snert]

My great grandfather invented the battery operated flashing light that used to be used on the top of the large orange traffic barrels. He received no money for the patent and his company put 2 other company men on the patent so they could claim majority ownership. They gave him a real shaft job.
Dave

My dad drew up the steam piping process for moving energy from one end of the Aliquippa LTV steel plant to another on a legal pad.

His foreman turned it in with his name on it.

yup. Screwed.