900 Meter 300 Blackout Round

[A-Game]

http://www.thefirearmblog.com/blog/2017 ... Newsletter

As much as I think this blog is little more than click bait and fake news, I would be curious to see this bullet.

https://drive.google.com/file/d/0B7pbyx ... haV3M/view

Enjoy!

[dellet]

Dr. Phil posted this in his thread, I'll be interested to see actual results, but it's certainly possible

viewtopic.php?f=141&t=101253&start=40

Well, it didn't take long for this to happen:
http://www.thefirearmblog.com/blog/2017 ... -hold-sec/
http://soldiersystems.net/2017/10/26/tr ... ive-range/

900 Meter 300 Blackout Round? Hold On a Sec



Idaho company Trom Technologies (formerly PNW Arms) is advertising a new 300 Blackout round that it claims extends that cartridge’s effective range to 900 meters, more than twice the generally accepted 400 meter value for that round. They claim the new round maintains a 100% chance of hitting an IDPA silhouette at that distance, and that it retains over 400 Joules of energy making it, they say, “effective on biological organisms of all kinds”. The company released a somewhat esoteric PDF that not only extolled the virtues of their new ammunition (which also comes in subsonic and .308 Winchester flavors), but details their corporate strategy of selling consumers “the subscription experience”. What this has to do with ammunition is not made clear in the file.
Down to brass tacks now: What Trom is advertising does not seem highly probable to me. Their round does seem to sport a streamlined turned copper alloy bullet, and projectiles of this type do tend to have very high BCs for their weight. However, a little extra digging begins to draw considerable doubt in my mind. Nowhere in the entire document are values for ballistic coefficient or even projectile weight given – yet we can determine both by the data presented therein. We calculate that a projectile possessing a muzzle velocity of 2,190 ft/s and a muzzle energy of 1,935 Joules must have a weight of 134 grains. We also know that in order to retain the claimed 393 Joules at 1,000 meters, that projectile must have a G7 BC of at least 0.27. This means that the projectile’s effective claimed i7 Form Factor has to be less than 0.75 (0.747, to be exact), which is beyond exceptional. An example of an exceptional brass turned bullet is the Warner Tool Company 155gr Palma Flatline, which itself has a G7 BC of 0.270, despite being 21 grains heavier. This projectile has an i7 Form Factor of 0.865, which means if the Trom values are correct, it is a 16% less efficient aerodynamic shape than the 134gr Trom. Yet, the WTC 155gr Palma Flatline is a much longer, better streamlined bullet which has an ogive 0.064″ too long to even fit within the 300 Blackout’s overall length.

These facts lead me to believe that the velocity and energy figures presented in the chart by Trom are unrealistic. This does not necessarily mean they were intending to be deceptive; it is relatively easy to accidentally produce inaccurate data which may seem to indicate that a projectile design performs much better than it actually does. It’s likely that they did experience a “100%” hit probability on an IDPA silhouette at 900 meters, although this is not so astounding an achievement as it sounds. Many, many bullets are capable of retaining their precision through the transition from the supersonic to transonic and then subsonic flight regimes. This was a key element to “heavy ball” machine gun projectiles like .30 M1 Ball and .303 Mk. VIII of nearly a 100 years ago, for example. So it is entirely possible that the Trom projectile produces a dispersion at 900 meters (which is beyond its supersonic range) that makes a hit on an IDPA silhouette highly likely, but this capability is by no means unique to that bullet, nor even particularly special or noteworthy.
I think until Trom submits their round to a third party for Doppler radar readings, I will remain skeptical of their claims.
 
H/T Soldier Systems Daily.

I had originally questioned the above comparison, the manufacturer does have PDF presentation making the 1000 meter claims. After taking a close look at the drop table included, the numbers are very believable based on my experience and Dr. Phil's shooting.

Here is the PDF file.
https://drive.google.com/file/d/0B7pbyx ... haV3M/view


The question that has needed to be answered was accuracy and stability through the transonic range, and Dr. Phil pretty well put that to rest a couple weeks ago. A bullet designed for 300 Blackout would achieve the numbers posted easily. The real problem is drop and 20 MIL/70 MOA compensation needed with a 200 yard zero.

The trick here, if there is one, is using Joules for energy instead of pounds.

A Berger 135 Flatbase
2200 FPS MV
1972 J ME
346 J at 1000 meters, 380 J at 900. 400 J at 850

Barnes 130 XLC
2200 fps MV
1899 J ME
333 J at 1000 meters, 366 At 900, 400 J at 820

Sierra 135 SMK
2200 FPS
1972 J ME
299 J at 1000, 330 J at 900, 400 J at 740.

To design a real Match quality copper bullet in that weight class should have no real problem making 400 Joules happen at 900.

Dr. Phil's load at 1900 fps should have more than 400 Joules at 1000 meters/1200 yards. That round in a 16" barrel would have 400 J out to 1250 meters/1350 yards. So I know for a fact it can be done, and he did on a target half the size..

This is why I have tried to promote bullets for the Blackout in the 140-150 weight range.

Edit for correction and add link to manufacturers presentation file.

[dellet]

So a funny thing happened on the way to finding the truth about this bullet and load. I basically got thrown out of the conversation on the Firearm Blog

The write up over there is less than favorable, the BS flag was thrown by more than one person. I basically stated that by looking at the numbers provided by the manufacturer, it was not only possible, but probable that it was true. All of those posts are still there, I post with basically the same name, Dellet BLK.

I laid out my case and was more or less told i'm clueless and don't understand things like BC, form factors, drag and such. Which in all honestly, I wish I knew more.

I suggested that all it would take to happen was a bullet of a certain BC. After being taken to school with a bunch of formulas, my response boiled down to, "but if you do this it will work". After a few exchanges I finally laid it all out.

I know the town the company is located in, probably have met the people involved in the project. They might embellish, but they don't lie.

I put forth the simple premise that the company simply published the data they had collected and it was being mis-interpreted. So I basically reverse engineered the circumstances to fit the data and posted it.

The post disappeared. So I figured I must have screwed up. I simplified the post with the same basic info and waited. The post was up, but flagged for review. A few minutes later, gone.

Clearly, my thoughts are not welcome there.

Anyway, I spent some time looking at the data, I know the area that the testing most likely took place in and quite possibly some of the characters involved. For thuse not familiar, the suburbs of Boise Idaho have become kind of an enclave of gun related manufacturers. This is where PNW, now TROM. is located.

So here's the controversial post, with what I think happened on test day. The numbers are solid. Altitude and temp reflect a normal summer day for the area.

Must of fat fingered a post, so I'll try again.

Let's for the sake of argument say that they actually did what they said they did. Trom is located in Potlatch Idaho, elevation 2750. Testing was probably done this last summer.

Using their numbers on velocity and JBM's calculators reverse engineer what happened.

2190 MV and 1023 fps at 900 meters plugged into the BC calculator (it will not accept distances great than 1000 yards). 85 degrees is a reasonably normal temp in Potlatch. Bullet weight 135.

Ballistic Coefficient (Velocity)

Input Data

Near Velocity: 2190.0 ft/s Far Velocity: 1023.0 ft/s

Chronograph Separation: 900.00 m Drag Function: G7

Temperature: 85.0 °F Pressure: 29.92 in Hg

Humidity: 25.0 % Altitude: 2750.0 ft

Std. Atmosphere at Altitude: No Pressure is Corrected: Yes

Output Data

Atmospheric Density: 0.06559 lb/ft³ Speed of Sound: 1144.1 ft/s

Ballistic Coefficient: 0.222 Time of Flight: 2.071269 s

08-Nov-17 13:16, JBM/jbmbcv-5.1.cgi

Gives us a G7 BC of .222

Plug that into the drag conversion and we get a form factor

Drag Function Conversion

Input Data

Ballistic Coefficient: 0.222 G7 Caliber: 0.308 in

Bullet Weight: 135.0 gr

Velocity: 2190.0 New Drag Function: G7

Output Data

Speed of Sound: 1116.4 ft/s Mach Number: 1.962

CD of Standard G7 Bullet: 0.300 CD of Standard G7 Bullet: 0.300

Form Factor of G7 Bullet: 0.916 Form Factor of G7 Bullet: 0.916

New Ballistic Coefficient: 0.222 G7 Sectional Density: 0.203 lb/in²

08-Nov-17 13:19, JBM/jbmgf-5.1.cg

Now we have a form factor of .916 and a G7 .222

A 135 Grain bullet, 1.400" in length with a G7 of .222 shot at a MV of 2190 goes into the calculator.

And what we get is 394J at 1000 meters at 984 fps

Pretty close to what they posted.

Sounds like the numbers make sense to me on paper.

If they are guilty of anything, it's gaming the location they chose to place their business. Or more realistically not providing the actual shooting day info.

It won't take much from here to be able to give you the profile of the bullet needed to fill in the rest of the story.

As I said in the beginning it's not only likely, but probable, that they did just what the numbers say they did.

This is the problem with calculators, if you don't put in the right information, you won't get the right answers.

My teacher on the Blog simply used default numbers for altitude and temp. 59 degrees at sea level and used those numbers to bash the results and claims.

The company never made any grand claims, other than they shot some bullets, they all hit the target and we have a great new bullet to sell you. To back that up they posted muzzle velocities and distances. If we assume they did not fake the whole thing, and I don't think they did, they produced a nice match quality load.

I will qualify that, with I think the load Dr.Phil put together is better. There may very well be some adjustments to that project coming, that will make it better.

So bottom line, I think the load discussed in the above links will do, what they say it will. It absolutely works on paper and should be promising out to 900 meters as advertised. As long as you do your own verified drops, which is another issue, at 900 meters with a 200 meter zero, you'll need about 55 MOA of adjustment, but what's 46 feet give or take a few inches between friends.

Nice to see some innovation. Just wish people that want to talk it down would take the time to make sense of things before calling BS.

[DaedalusX]

I really don't see the big deal to be honest

I could easily get some 155gr flat line bullets and load them really long and hot in a 16" R700 and at 4000 density altitude and if there's no wind I'd be able to achieve the same thing. The wind is what would ruin your day ... not the dope and the energy. I remember back a couple of years ago on snipershide, there was guy who was shooting Berger OTM 175 at 2000 FPS as a reduce 308 load to show that they were transonic stable.

It's really not that hard to do...

At the end of the days, doesn't really matter, it's all marketing buzzwords...

[dellet]

I really don't see the big deal to be honest

I could easily get some 155gr flat line bullets and load them really long and hot in a 16" R700 and at 4000 density altitude and if there's no wind I'd be able to achieve the same thing. The wind is what would ruin your day ... not the dope and the energy. I remember back a couple of years ago on snipershide, there was guy who was shooting Berger OTM 175 at 2000 FPS as a reduce 308 load to show that they were transonic stable.

It's really not that hard to do...

At the end of the days, doesn't really matter, it's all marketing buzzwords...

I think the "big deal" if there is one is that this is loaded ammo available in theory off the shelf.

The other thing, for this community, is that they designed a bullet and load that would fit in a magazine. It's not limited to a bolt action.

By the numbers posted, if correct, it is actually a very well designed bullet and they actually have two others. One for subsonic use and one for a .308. For a marketing ploy, they chose what many people consider and under powered cartridge to prove their bullet.

Your reference to the Flatline bullet is where we went with the 154 G9. The velocity loss due to powder capacity restriction was balanced out with BC.

Dr. Phil tested that bullet at probably less than 1000' out to 800 yards in a magazine fed 10.5" barrel. He had first round hits on half size silhouettes to 700 yards and blamed himself for the first round miss at 800. Personally, it think that is more interesting for the Blackout community. Being able to compete in 600 yard matches with an SBR chambered in Blackout would be different.

My point to the fire arm blog, as you have also said, is that it can and has been done. When I tried to back that up with the same type of paper stats I was being beat over the head with, my posts were removed. And that's BS.

[Bob the nailer]

Seems like groups will shut you down if you don't drink the koolaid. Nice to know sites like this one support good solid info on cartridge work.

I know for one I wouldn't have my subsonic load developed if it wasn't for help on this site.

[MORT1]

SAYS IT ALL!!!

https://www.youtube.com/watch?v=wg2iR6vjwQU&t=2s

[dellet]

SAYS IT ALL!!!

https://www.youtube.com/watch?v=wg2iR6vjwQU&t=2s

Yeah, but I read somewhere on the internet that the bullet could not hit the target as hard as they said it did.

[MORT1]

Must be true then.........you won't catch me standing around to find out!

[dellet]

Must be true then.........you won't catch me standing around to find out!

You have about 1.5 seconds after seeing the flash, what could go wrong