“Officials say Thomas Matthew Crooks, 20, took his shots with an AR-style 5.56-caliber rifle…”
Yes, I’m very familiar with propaganda. I’ll believe it if the owner of the shop says it, or something like that. CNN telling me that the FBI did something is worth less than zero.
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We don’t know which ammo he used. If he had multiple 30 round mags, then a box of 50 won’t fill two of them.
most likely but we don’t know for sure.
all it takes at the most, is a barrel, bolt, and magazine to change calibers…
Yes but they were either 5.56 NATO or 223 Rem rounds, because that’s what the gun is chambered in.
We’re dealing in MOST LIKELY scenarios here. Not fantasies.
There is ABSOLUTELY zero evidence that it was anything OTHER than 5.56 or 223 and we have NUMEROUS sources saying it WAS a 556 AR-16. So what’s your point?
Absolutely. I agree. But Chris had suggested their was onboard gating or limiting on the mic, which is why I asked about both to see if he got this settled.
Did you see anywhere on the tread or in videos where the mic/board/effects rack info was identifed? I can’t find anything on it.
Hey @greg_n here is the solution for the bullet sonic boom (crack) time.
Positions:
M – muzzle position;
1 - bullet location where sonic boom is emitted;
2 – receiver;
B – perpendicular position of bullet trajectory (M:3) relative to position 2;
3 – bullet location when sonic boom is received on 2;
Deduction:
Eq. 1 and Eq. 2, define the position and velocity at position 1 using kinematics equations.
Assuming a constant deacceleration will be good assumption based on my simulations of ballistic calculators. I had calculated the reduction of speed and estimate a medium deacceleration.
Eq. 3: is the sonic boom distance D2 to the receiver (1:3).
Eq. 4: the right triangle 123 is similar to the right triangle 1B2 therefore the sides and hypotenuse are proportional.
Eq. 5: Isolating t2 from Eq 4.
Eq. 6: Applying Pythagoras on the right triangle 1B2 and using Eq.5 and Eq.3.
Eq. 7: rewriting Eq. 6
Eq. 8: substituting Eq. 1 and Eq. 2 on Eq. 7
Eq. 9: assuming a=0 from simplified model and isolation t1 in Eq 8.
Eq. 10: Crack time is the sum of the time of bullet from M to 1 and time of sound from 1 to 2.
Eq. 11: Applying Pythagoras on the right triangle MB3 converting distance to time for the sound of the report from M to 2.
Eq. 12: Simplified solution time difference (crack – report) for a=0. Derived from Eq. 9, Eq. 10, Eq. 11, Eq. 5, Eq. 1, Eq. 2.
For the complete solution with deacceleration depends on solving Eq. 08 witch not solvable by radicals, so I used newtons method. For that I started the method at the time from equation 9.
After finding the solution I compared the simplified solution for Trump position using medium velocity and the complete solution with deacceleration. I conclude that using the medium velocity the simplified solution one (Eq. 12) is almost the same result. 
Plotting the solution in the line fire, I manage to create a chart representing the time differential of crack and report. Where Stew was the probable time differential is 0.03s.
(edit) The lines in the chart are isolines where the time differential is the same. For example, at Trump position is around 0.22s but for someone on the North-East part of the middle bleacher would be around 0.17s.
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Last I counted there were over 80 calibers used in the AR platform.
This is NEW analysis built on what I did in my previous post.
To refine and derive how close those first three shots were to Trump’s microphone:
vs = speed of sound
vb = average speed of bullet
d = distance from muzzle to microphone
dc = distance from muzzle to bullet closest point
ε = distance from bullet to microphone at closest point
treport = time of report arrival at mic
tsnik = time of snik arrival at mic
t0 = time of shot
Δt = treport - tsnik
d = vs x (treport - t0) => treport = d⁄vs + t0
dc = (d2 + ε2)0.5
tsnik = dc⁄vb + ε⁄vs + t0
So Δt = d⁄vs - (dc⁄vb + ε⁄vs) = (d - ε)⁄vs - dc⁄vb
As ε increases, Δt decreases. I plotted this on Desmos for anyone who wants to look and play around with.
The assumptions all calculated accurately in my previous post are:
- Distance shooter to mic d = 454 ft
- Velocity of sound vs = 1152 fps
- Average bullet velocity vb = 2644 fps (assuming a 77gr OTM bullet)
If you play around with the bullet velocity slider in the Desmos plot, you’ll see immediately that the ONLY average bullet velocities that make that first shot come close enough to the mic to have hit Trump, but not closer than he actually was, and still yield a 220ms snik-report (Δt) interval, are between roughly 2620 and 2644 fps.
The fact that the snik-report (Δt) time of the 1st shot was the largest is also clear proof that it was the CLOSEST shot to the microphone (and therefore to Donald Trump), which makes sense, because that is the only one that hit him.
The other shots produced snik-report intervals (Δt) that were 5 to 10ms SHORTER.
The measured snik-report (Δt) intervals of 220ms, 215ms, and 209ms for the first three shots imply that those three bullets passed at the following distances from Trump’s microphone:
- 2.75 ft
- 8 ft
- 15.25 ft
Does anyone have an accurate estimate of how far Trump’s ear was from the microphone???
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that’s consistent and very realistic with how a 5.56 round fired from a 16" AR-15 barrel performs in real life testing
Do you trust the source of the that info. Remember, it is very likely the same source that stated he carried the 5’ ladder to the site.
It doesn’t matter a whole lot difference between 223/556, as long as we assume the same rifle fired all 8 shots… but, as we’re seeing in this citizens investigation, it’s highly unlikely all 8 shots came from the same rifle. This is where things begin to fall apart, because now we’re dealing with yet another unknown variable. I haven’t gone deep into the data, others are doing a great job of that, but there is about 100-150 fps difference in velocity between 223 & 556.
WRT other comments on suppressed rifle, I suppose I could borrow a friends 308 and put a suppressor on it, but I don’t believe he has any subsonic ammo, and it would be a crap shoot if it would even cycle properly.
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Do you trust the source of the that info.
Yes. The fact that you have a problem with it, is…well…a personal problem. I can’t help you with personal issues, sorry.
Remember, it is very likely the same source that stated he carried the 5’ ladder to the site.
And people reported van, explosives, all kinds of shit that we don’t have info about, yet people cling onto that as being true. Oh well, you guys cherry pick, I will too.
It doesn’t matter a whole lot difference between 223/556,
Uhhhhhh yeah buddy it does matter. 5.56 bullet will do more damage.
as long as we assume the same rifle fired all 8 shots…
You all can assume whatever you want, to me it’s pretty clear and obvious 8 shots came from outside the building.
but, as we’re seeing in this citizens investigation, it’s highly unlikely all 8 shots came from the same rifle.
It’s highly unlikely to you, not me lol
This is where things begin to fall apart, because now we’re dealing with yet another unknown variable.
Variables…you made up…
I haven’t gone deep into the data, others are doing a great job of that, but there is about 100-150 fps difference in velocity between 223 & 556.
Right, but do you have any reason to believe he would use 223 ammunition over 5.56?
WRT other comments on suppressed rifle, I suppose I could borrow a friends 308 and put a suppressor on it, but I don’t believe he has any subsonic ammo, and it would be a crap shoot if it would even cycle properly.
But if you shot it indoors there would be a strong residue of freshly burnt gunpowder, which all the people in the building would have noticed. So you’d have to be somewhere outside imo.
Yes, I know. I calculated it in my previous post using the actual data and for a 77gr OTM round using a ballistic calculator taking into account all the various possible parameters.
I was just saying it because people here have been using 3000+ FPS for their calculations
Yes those numbers around 3000 fps would be accurate for 55 gr rounds.
That’s why the key questions now are
-
WHAT WERE THE ACTUAL RECOVERED BULLETS?
-
How far was Trump’s head from the microphone?
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But difficult for an AR-15 with a 16" barrel to pull off.
Daniel Defense AR-15, using Hornday Match ammo at 75gr was getting around 2500+ FPS…
I just ran 223 and 556 across chronograph yesterday with my 16" barrel
556 - average velocity 3035 fps
223 - average velocity 2914 fps
223 commercial reman - average velocity 2905 fps
The rifle on the roof was not a 16" barrel.
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So just to confirm, all of your 55gr ammo shot out of a 16" barrel went faster than 76gr match ammo?
The rifle on the roof was not a 16" barrel.
Source???
Heavier ammo generally goes slower than lighter ammo. As you start to get into reloading, twist rate plays a very important part of velocity. A bullet needs to be stable, and if it spins too fast, it can literally come apart. 2500 is about where 77gr would be. Even more so than 556, buying 77gr would be much less apparent on the shelf. 223 55gr is by far the most common wt.
16" barrel is on the upper, and typically will measure 16" from the front of the lower to the end of the flash hider. The lower with an extended stock, will also measure 16". The rifle on the roof very visibly is longer from the front of the lower when compared to the lower section. While I can’t tell if it’s 18" or 20" (rarer), it is not 16"
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Heavier ammo generally goes slower than lighter ammo. As you start to get into reloading, twist rate plays a very important part of velocity. A bullet needs to be stable, and if it spins too fast, it can literally come apart. 2500 is about where 77gr would be. Even more so than 556, buying 77gr would be much less apparent on the shelf. 223 55gr is by far the most common wt.
76gr ammo performs better at distance, against wind. That’s why it should be preferred. But if he used 55gr then maybe that’s why wind caused such a variation on a moving target.
16" barrel is on the upper, and typically will measure 16" from the front of the lower to the end of the flash hider. The lower with an extended stock, will also measure 16". The rifle on the roof very visibly is longer from the front of the lower when compared to the lower section. While I can’t tell if it’s 18" or 20" (rarer), it is not 16"
Using a quick eye test it looks like a 16" rifle lol
Cop in black uniform probably has SBR since it has a silencer. SWAT guy seems to have a 16" barrel, and when you compare it to the rifle on the ground it doesn’t seem to be smaller to me.