Random thoughts on ballistics...
Jeremy has 32 years federal experience. Twenty-three of those were as a Special Agent and member of an elite Federal SWAT team. There he served as a trauma medic, firearms instructor, assaulter, assault team leader, senior tactical instructor, sniper, sniper team leader, and sniper instructor.
While serving in the USAF, Jeremy was certified in trauma care, munitions, freefall parachuting, SERE, and later, served as a Special Agent in AFOSI.
Jeremy has won first place in IDPA, USPSA, OFLEA, and PPC competitions. He has been awarded Oklahoma EMT of the year and the FBI Shield of Bravery, the second highest medal for valor in the FBI.
Jeremy loves spending time with his family and friends, serving with his church, and lifting heavy things.
Great day for off-angle shooting (and math)!
How far away is that car? Its license place covers two milliradian in the reticle, and plates are always 12 inches across. (T-in * 27.76/T-mil). So it’s 166 yards away.
So, set the scope for 166 yards? Not yet. You’re 90 feet above the target, so the bullet only is affected by gravity for ((A*A)+(B*B) = Hyp). So, 163 yards.
Wind is 10 knots gusting to 15 from 45 degrees (half value) but wind correction, well, it’s still 166 yards of wind. So hold left 0.5 mils.
Now…breath. Relax. Just gentle pressure on the trigger.
This is what happens when the gas tube gets sick and tired of the giggle-switch. It ejects right out the front.
LE Select-Fire Instructor Certification (CLEET #22-1620) will be available July 2022.
Here's a good example of where a 50/250 zero works on a varmint rifle. The rifle is dead on at 50 and 250 yards. The point of aim for both groups in the photo is the neck. So the 200 yard group hits a couple inches high, and the 300 yard group is a few inches low. That makes life easy when varmint hunting at night. Hold center and send it.
(This rig had a 14.5" P&W White Oak 1:8 twist stainless, mid-length gas. Raptor 4x night scope with Atilla infrared flood and laser, and AAC-M4-2000 suppressor.)
Two important lessons from the range today:
1. The MPX hates the trilug.
2. A sling stuck under the charging handle can shut the gun down hard.
First lesson: 10-shot groups with a 3x magnifier from a rest at 50 yards with a Rugged Obsidian on a trilug produced crummy groups:
Gold Dot 147: 6".
HydroShok 147: 3.75".
SXT 147: 5".
G2 147: 6.5".
Ball 147: 3.5".
Critical Duty 135: 4".
By way of comparison, a beat up 10.5" AR with a 1x Romeo put up a 1.5" group with junk ammo.
Second lesson: If you work a stoppage and your sling is under the charging handle when you rack it, it can shut the gun down hard.
October 1, 2021
When you realize you’re talking to your people:
- Nice rig. Is that a six or a six-five?
- Oh, it’s a six-five. The six is flatter, but I’ll take the better barrel life.
- The Creed is easier on the leade, for sure. What’s your load?
- Match kings over 4350 for practice. Bergers for matches. SD’s stay in the teens.
- I like the secant ogive on the Berger for transonic, but I have to play with OAL. You jump them to the lands?
- Actually, these are hybrids, but I still jump them a little bit. These are two-eight-oh. I just crimp below the cannelure.
- Trim every time?
- Yeah. And anneal. What’s the twist on your 762?
- It’s a 1 in 8. It’s tight, but it spins subs well suppressed. No baffle strikes so far, but a good bit of gyroscopic precession with supers past 300.
- I bet. Well, good shootin’.
- You as well, sir.
October 16, 2021
Pick your “truck gun”:
4” MPX (9mm) vs 10.5” AR (5.56mm). What’s your pick and why?
Weight - Same (8 lb 2 oz).
Overall length - Same (when MPX is suppressed).
Accuracy – 5.56mm (1” vs 3” at 50 yards).
Range – 5.56mm = 300-400 yards. 9mm = 100.
Capacity – Same (30 rounds).
Lethality – With typical ammunition (M855, 55 FMJ), 5.56mm from a short barrel will be less effective than 9mm JHP. With a premium bonded round, the 5.56mm will outclass 9mm JHP.
Report –The 5.56mm will cause immediate and permanent hearing damage. The 9mm is hearing safe.
P.S. Is a rifle caliber always better than a pistol caliber? Check out the ballistics of a 5.56mm below 9” to a 9mm of the same length, and you might be surprised.
August 28, 2021
10mm vs 357 Magnum for back country. Which one would you pick?
The Ruger GP-100 Wiley Clapp .357 Magnum and the SIG P220 Elite 10-mm are two very different firearms with very similar stats. They weigh about the same, they have roughly the same barrel bearing surface length. Surprisingly, with the best loads available, they are virtual ballistic twins!
Unloaded Weight: SIG at 2 lbs, 10 oz. vs Ruger at 2 lbs, 5 oz.
Advertised barrel length: SIG at 5” (including chamber) vs Ruger at 3”.
Actual barrel bearing surface (minus the chamber): SIG at 3.5” vs Ruger at 3”.
External Ballistics: SIG with 180-grain Gold Dot hand load (11 grains Blue Dot) at 1,317 fps vs. Ruger with Buffalo Bore 180-grain hard cast at 1,313 fps.
Ammunition Capacity: SIG at 9 rounds vs Ruger at 6 rounds.
Recoil: The SIG felt recoil is substantially less than the Ruger with similar loads.
Trigger: SIG SAO at 5.25 lbs vs Ruger DA/SA at 4 lbs.
August 4, 2021
I know a cartridge can’t make your barrel longer, but can it make it act like a longer barrel?
As it turns out, yes. We used a 55-grain open tip and a bonded soft point. For each option, we selected both 5.56 (hot) and .223 (normal) pressures as loaded from the factory.
The results showed that a .223 round, on average, is about 230 fps slower than one loaded to 5.56-mm pressure. So, hotter ammo is faster. That easy. But when dropping from a 14.5” barrel to an 11.5” barrel, you almost always lose 200 fps.
Here’s where the numbers are most interesting. Look at the blue shaded boxes in the chart. The 14.5” with .223 ammo and the 11.5” with 5.56-mm loads both end up at around 2,700 fps. It’s the same bullet, and it’s going the same speed. So, it’s the same ballistics.
Look at the orange box and you’ll see the same thing. The 14.5” with the .223 round produces slightly less velocity with the same bullet as the 11.5” barrel with the higher-pressure 5.56 loaded rounds. Again, you get the velocity back from the shorter barrel by loading 5.56 pressure rounds.
You might ask: who cares about a measly 200 feet per second? Well, remember that in real-world testing, the mighty 300 Win Mag launches a 168-grain slug at about 2,990. That’s only 230 fps faster than the lowly .308 when both have 24” tubes. So, yeah. 200 extra feet per second is a big deal.
You can’t load a round that makes your barrel longer, but you sure can make it act like one.
The Shield Arms S-15 magazine is arguably the best innovation in Glock aftermarket products for this decade.
As such, it has become very popular for G43X owners, but with mixed reviews on reliability. Shield offers a 10-coil mag to improve reliability, but some users still encounter stoppages. After 3,550 rounds of testing on three 43X's we determined that the 12-coil spring provides the best reliability with a reduction to 14-round capacity. (They are all Glock springs, so just get one from your favorite gun store.)
We all want G19 capacity in a G43X frame, but you can't put a 350 in a Miata without a few tweaks.
Be safe, and send it!
I got to spend the day with my old buddy and US Border Patrol Firearms Program Manager. He brought me one of their G47s. You can’t buy one of these in stores! It’s like a G17 that can slide swap into a G19 or a G45. Cool stuff!
My most recent tinkering: I rebuilt an old AR that has been run hard. This blaster has had only 3 stoppages in 7,100 documented rounds! It has worn a suppressor for nearly all of it. There were a grand total EIGHT times it was cleaned in 11 years. In the photo, you can see the gas block was essentially 99% closed and seized in place. It’s evidence of how little gas a suppressed AR needs to run reliably, even when it’s filthy.
Autoglass is tougher than you might think. The trick is not to aim through the holes. Shoot through the holes. ￼
In May 2010, a man detonated a bomb outside a place of worship in Jacksonville, FL. After learning a federal agency suspected him as the bomber, he fled the state. A year later, in 2011, the subject was located in Glass Mountain state park in Oklahoma. A federal SWAT team was activated and a two-man sniper team was sent out that evening to locate the subject under cover of darkness. After a long patrol, and using only night vision to search and navigate, the snipers located the subject. The snipers quietly positioned themselves on top of a nearby mesa and set up a surveillance position until the sun came up and the assault team moved in.
After a standoff that went into the early afternoon, the subject emerged from his tent firing an AK-47 at the assault team operators. At this point the snipers had been awake for over 31 hours and had been lying motionless and out of water for several hours. Upon seeing the subject firing his rifle, the sniper immediately engaged the subject with one round from a .308 sniper rifle at a range of 210 yards and ended the threat.
Considerations: Despite the average sniper engagement falling under 100 yards, be prepared for longer ranges. Know your holdover, wind deflection, and down-angle calculations. Brace yourself for lack of sleep and dehydration. Sweat in peacetime so you don’t bleed in wartime.
December 24, 2020
This is a good example of error from shooter/spotter offset.
This is a 300-yard shot with the spotter only 10 feet right of the shooter. The shooter is engaging the small 8” gong.
The left photo shows the spotters’s perspective: the rounds are digging a hole 2.5 milliradians *right* of the target.
The right photo shows the shooter’s perspective: he can see his rounds digging a hole 1.5 mils *left* of the target.
Being 10 feet from your shooter causes a BIG perception error.
December 12, 2020
Whoever said trigonometry isn't fun, didn't understand the application to long-range ballistics. SOH-CAH-TOA is the mantra of the modern marksman!
We got to provide some precision live-fire for Oklahoma State University while testing a stadium active-shooter detection system. Many thanks to the engineering students who designed the bullet trap!