Calculation of Bullet Drop/ Various Models

[HappyHellfire]

This is actually unbelievable.

You took what is considered one of the worst bullets to use in a 308 past 600 yards. Copied its profile, made it out of copper reducing its weight 24 grains and used that bullet for a comparison claim?

A fictional bullet for comparison, did I understand that correctly?

There are probably 20-30 150 grain 308 caliber bullets that will retain 600 pounds of energy to 225-250 yards with a muzzle velocity of 1785 fps. A few that will be 275-300 yards. The 150 gold dot designed for 300 BLK is one, about 235. It’s a lead core plated bullet that costs about 23 cents. It is capable of sub 1/2 MOA out to 300 yards.

Your bullet needs to have 600 pounds well past 300 yards for your claim to even be sort of true.

Just as a side note, you claim to have shot hundreds of rounds for testing a single bullet. I can claim to have tested hundreds of different bullets in a single cartridge.

Are you starting to get an idea of the skepticism of your claims yet?
I’m a nobody, probably why many of the heavy hitters haven’t even bothered commenting.

Edit to add Aerospike performance table
View attachment 1566750

You asked why you should try them. This is the original research that shows the same bullet with the same weight with only an aerospike base gives a big improvement. When I eventually get to lead core bullets the weight will increase but the aerospike base should work with them as well. If that is unbelievable then I don't know what to tell you other than I work on statistical certainty and not belief.

Can you find a lead core that is better? Probably. Can you find a copper that is better? No. This is a startup company. If you don't want to take the risk then just pass.

 

[dellet]

You asked why you should try them. This is the original research that shows the same bullet with the same weight with only an aerospike base gives a big improvement. When I eventually get to lead core bullets the weight will increase but the aerospike base should work with them as well. If that is unbelievable then I don't know what to tell you other than I work on statistical certainty and not belief.

Can you find a lead core that is better? Probably. Can you find a copper that is better? No. This is a startup company. If you don't want to take the risk then just pass.

Let me ask this a different way.

Why would I invest in a product or person whose sales pitch is a 40% improvement over another product that doesn’t exist?

Statistically speaking, that would be a very poor investment wit a very statistically high average for disappointment in product satisfaction and success.

Statistically speaking miss representing a product, ends poorly.

I’ll probably buy some to try at some point, but I have a much better idea of what to expect than many others who will make the same investment. I doubt I’ll be disappointed with the results. I also doubt your bullet will be the best Ive ever tested.

Plenty of other people will read your claims and after testing wonder why there is not a class action lawsuit for miss representation. Even more so when they find out your comparison bullet never existed. There never has been an actual comparison.

You can solve that by making clear all your claims are in models. Not reality.

Right now this has nothing to do with the performance of the bullet. It has to do with the integrity of the claims.

 

[davidjoe]

The rebated boat tail designed DTAC bullets that David Tubb sold, manufactured by Sierra, shot well. This design reminds me of those. With a lower density, a copper bullet will be more prone to drift although one comes to mind that I have used with a shockingly high BC, but also with a true needle nose, the Lehigh Defense .375 solid, which is also amazingly accurate.

Can’t fault you for experimenting. Improvements at this point will necessarily be incremental. A solid in string fire is an expensive proposition and I don’t recall reading of test results, differences in barrel wear and so forth. In ELR, extreme range, lowest round count, solids do rule, and at the range of 50 yards, with the highest volume, waxed lead will shoot one hole.

There’s a strong bias toward solids, the more critical “the” shot being made is. They literally have reloaded some of them in the big game world, after retrieval, while at the opposite end, lead core bullet failures in matches with outwardly perfect bullets is a risk that must be recognized and managed.

 

[Dave M.]

OK, here goes.

When I first started I used the Sierra 168 BTHP data from McCoy's book on external ballistics as a reference projectile. Unfortunately, the data didn't match because when you buy the Matchking 168 grain BTHP it appears to have a slightly different ogive then McCoy's data. So what I did was crate a "Moch 168" that had the same shape as the published data out of solid copper for comparison. I then collected data on both the Aerospike Bullet and the Moch Sierra that had almost the exact same weight. The data looks like:

View attachment 1566733

This allowed me to compare the same bullet ogives with the only difference being the base. As you can see, at higher velocities, the two are similar but the Aerospike diverges at around Mach 1.8 and stays lower.
I then used a ballistic simulation to see the comparison between the Moch Sierra, the Published Sierra, and Aerospike. Based upon these simulations, the Aerospike from a 300 Blackout with a MV of 1785 ft/sec (Mach 1.6) would have an effective range out to 600 ft-lbs of impact energy of about 40% longer range than the Moch Sierra (similar nose and weight).

The 30 Cal Aerospike that I have for sale has a Von Kaman ogive that is 2.538 calibers long. This reduces the drag curve even further to give an effective range of 40% further than the plain old Sierra 168 "McCoy's data" but makes the bullet marginally stable out of the .308. Given that most manufacturers won't release their full drag curve, I can't say how my bullets will do against existing bullets without much more testing.

The bullet design was compared to the SAAMI standards for the 300 AAC Blackout to make sure it meets the standard as well as test fired (hundreds of rounds). The bullet has an overall length of 1.314 inches.

I know that it is a risk to try a new bullet. That is why I sell the trial packs so that you can try them without a big investment. If you don't like them, fair enough. I just really love this research and think that these will eventually replace boattails.

This is exactly what everyone has been saying to you for days now, you are selling a product that you truly don’t have much real life data on. Furthermore, your claims of 40% improvement do not seem to be substantiated by any real life comparative fire data. I know you think I’m being hard on you, but I would literally give the same advice to my son if he was trying to sell a product with a lack of data.

 

[wwbrown]

I checked them both out and it looks like JBM has a whole set of calculators. I bet he writes them for fun like I do. One of them is obviously the 4DOF but some of them look like the more simplified ones.

I believe his main solver is just.a modified point mass approach straight out of McCoy. I say this because my solver using the same matches his to at least three digits, at least it did when I developed it back about 15 years when I developed it. I added the caveat in case JBM has changed its solver over the intervening 15 years.

I found JBM to calculate trajectories of supersonics accurately out to 1,000 yards whenever it seemed off by more than 0.5 MOA I would carefully verify all inputs. I use JBM whenever I need a solver as the GUI makes it much easier my solver was written to be included in an integrated system, the intent was not an HMI device.

 

[wwbrown]

That radar costs $250k. I had one at dahlgren. It's on my Christmas wishlist.

Go to one of Litz's seminars or matches that he sets up his Doppler radar for customized drag profile. As I said before earlier the consumer radar units like labradar which gives you the trajectory for maybe the first 300 yards is a poor way to estimate drag curves given the SNR problems discussed earlier.

Extrapolating your drag curves to the subsonic based on the 300 yard samples is suspect at best. I think if you submitted these results to a peer-reviewed journal you would get called out on the range of your measurements pretty severely. I especially question the extrapolations when you yourself say the sweet spot is Mach 1.4, given you have no experimental data to show this claim is weak. I am not including computer numerical results as "experimental" data and maybe just dated myself.

Your drag curves may be decent estimates of the actual but until you can verify either by direct measurements of the trajectories (Doppler) or bullet drops measured with samples over the full range of distances you are claiming I think they should watermarked as preliminary results. Your extrapolations are too large, 300 yards of measurements in the lowest SNR realm is no way to make estimates for ranges four times that far.

If I have misrepresented or misunderstood your work/results I apologize. Trying to ascertain what you have done when you are presenting your work here chunk by chunk across multiple sub-forums versus a journal format is difficult.

 

[762willdo]

Do you really have to start off each new thread you post like a robot with the same cut and paste introduction?? We get John, sorry Dr. Stutz, you are a doctor, you teach ballistics to engineers and students…..blah blah blah.

Like dr. Jill Biden?
if you can replace a human heart or kidney or cut the tumor out of a human brain, go ahead and call yourself doctor and until then Idjust leave that off…..

 

[Bottom Fodder]

If you were looking for critics for what you’re doing, I think you came to the right place. I have no dog in this hunt but wish you well

 

[JLT]

Belief has nothing to do with it. I have over 95% confidence based upon testing. Compared to defending a thesis, this is a walk in the park.

This statement is true!