Is it like a concussion? Does it just happen only when you shoot or does it linger afterwards? I’m LH and after I shoot my 416- my right (opposite) shoulder hurts. I read that a recoil headache can affect shoulders as well. Maybe it’s just poor shooting form- I’m going to have my shoulder checked for arthritis too- I have some in my lower back.

I get them. It's like a shock to your brain...above about the 6.5x55 level of recoil...say 8 pound rifle, 2600 fps with a 140 grain bullet...

Also noticed slower recoiling loads...big bullet, slower...don't affect me as much.

For sure, the "snappier" the recoil, the worse for me. It's an odd sensation...almost like an invisible force slams into my skull.

Not pleasant, and annoying, because my shoulder and body can handle recoil just fine.

Have a Remimgton 700 DBM srainless in 300wby with a factory break, shoot 5 shoots and your have a headache, only gun I have that does this to me

Could it be the stock?

Could it be something of a misnomer? The fumes from expended nitro compounds can cause vicious headaches...in extreme cases, a debilitating headache similar to migraine. High percentage dynamite is brutal in underground mining and tunneling. Not everyone suffers from it, and eventually the new miner builds a resistance to it. I worked for an underground mining outfit in Idaho briefly, the miners would shoot their shot just at quitting time, let the face ventilate overnight before going back the next day to muck out. New miners were advised to smear a little dynamite on their hardhat headband to get over 'powder headache'. I think it was nothing more than a cruel joke.

I'm pretty sure it's about the recoil impulse and not fumes. The 243 and 308 Winchester are both burning a bit over 40 grains of powder, so if it were the fumes from combustion there'd be little difference.

My wife Eileen has been getting them since around 2007. Before then she regularly used an Ultra Light Arms .30-06 with full-power 165-180 grain handloads, and a couple of light 12-gauge shotguns.

Her first recoil headaches were with one of those shotguns, but soon afterward she couldn't shoot a Ultra Light Arms .270 with 130-grain loads. But she's had to steady step down since then.

Today her "big" rifle, used for elk, is a .308 Winchester with 130-grain Barnes TTSXs loaded down to around 2850 fps, and year or two after starting to use it she also added a muzzle brake. Her deer/pronghorn rifle has been a Tikka .22-250 for the past several years, using the Hornady 70-grain GMX bullet at around 3300 fps. Her shotguns are usually either a 28-gauge SxS for upland or a Browning Gold 20-gauge autoloader for waterfowl, a gas gun that also mitigates recoil.

It doesn't generally have anything to do with stock shape (much less powder fumes) but how hard and fast the butt-end hits the shoulder. Like Eileen, many people find recoil headaches get worse with time, mostly because people's bodies become less flexible with time.

I knew a dude once......it wasn't me...
This dude built a lot of large caliber rifles, 458's, 500's, etc. After about 10 rounds of anything more than a 338, the target would start to get blurry. This went on for years. He was running his lathe one day and got light headed. Turned the lathe off, fainted and fell back on the concrete floor. Bloodied the back of his head, and somehow bit through his bottom lip. Called the ambulance, they checked him out, said he was ok. Next day he went to a doctor. They did a MRI with dye in his veins. Turns out he had been getting concussions for several years. Doc said to quit this or you will die. So he quit shooting large caliber rifles with full power loads. Want my advice ? Do not fart around with recoil if your brain is telling you its too much. You wont win.
Charlie

It's happens at 9 years old when your dad hands his double barrel 12 gauge to you and points at the rabbit.

Dad was big on learning through personal experience

Some get "lucky" and don't get recoil headaches, even though they shoot hard-kicking rifles (or shotguns) a LOT.

But I know two such people who in the past year had to have their "shooting shoulder" replaced/rebuilt because of the damage done by years of such shooting. Maybe their shoulders starting to stretch/break didn't transmit as much "bounce" to their heads....

What load do you use for 130G TTSXs in a 308?

Do the recoil headaches remain a while after shooting? Or do they dissipate when you quit shooting?

There have been concussion research going on in football and hockey leagues . Rather reluctantly I might add.

It's something that only affects us wimpy types, not REAL MEN.

Not for a real "concussion headache." Your head is porous- sinuses, ear canals, mouth and even your eyes. All of these allow the concussive force of explosions that happen around you to interact with your brain, and it is very well established that the results of this are immediate and bad at best. Essentially, every round that goes off near your head is a small traumatic brain injury if you're not using good ear pro that is worn properly. Really the best case scenario is to wear both "over ear" and "in ear" when shooting anything big.

With Eileen the headaches start after 3-4 rounds with rifles where she can tolerate the recoil, and get worse with each round. Taking more time between shots, say while sighting-in a rifle, helps. They remain but start to dissipate after she quits shooting.

The handload with the .308 and 130 TTSX is 45.0 grains of IMR4895, in RWS brass with CCI 200 primers. It shoots very well--the last time she confirmed zero she only shot two rounds, which touched at 100 yards.

It's not just report, it also involves the shoulder being somewhat connected to the "headbone."

Eileen has always worn very good ear protection, but we were eventually able to pin it down to rifles that recoiled more than about 15 foot-pounds, according to the standard recoil formula. And after she had the muzzle brake installed on the .308 she could definitely tolerate shooting the rifle more before the headache starting to show up, even though brakes are louder.

i Get them, sometimes ultra fast, sometimes very slow. For me, very debilitating..can take 8hrs or more for relief
They are concussions, just like football. If you know football, they are now checking lineman to see if they get mini concussion on every play.
I know, I have had them from years of sporting events.
My limit now is 270win, even a full power 44 mag will do it.
I use a lead sled, and will still get them. Sometimes??
I also think the concussion of the rifle, and or when you put your head down on the stock, and it picks your flap up can cause it.
I shoot inside a cabin, so IMHO, that ups my exposure.
I am experimenting with different conditions to try and help,
Yes, different stocks can help, or hinder recoil.
Just sold a savage super light that recoiled way above its weight in 6.5prc.
I shoot a Forbes Ultralight in 270 that recoils half of what the Savage did. It should not according to powder volume, and bullet weight, but it did
Anyway...

This is a most unpleasant combo. I can only fire a few of these before I have to stop. It just plain hurts. And leaves me with a sore cheek and a mild headache.



666 grain slug at 1,604 fps in a gun a little over 7lbs generates about 64 ft/lbs of recoil energy. More than a 10 gauge 3.5" 2 1/4" load at 1,200 fps in a 10.5lb gun. That's several ft/lbs more than a .458 Win Mag 500 grain at 2,100 fps in a 9lb gun.

Just about any 12 gauge 3.5" heavy load will generate more recoil than a lot of the African big bores.

For really heavy recoiling rifles, it doesn't matter how good your ear pro is- they still release enough concussive energy to cause damage to anyone around where they're going off, whether you're on the gun or not. Another great reason not to shoot magnums

Yeah, I know that--but she has never hunted with a rifle chambered for a cartridge larger than the .30-06.

An afternoon of 458WM and 500NE will give me a headache into the evening, needing paracetamol before bedtime. Shoulder is fine.

Gough Thomas wrote that the nitrites and nitrates in the fumes of nitro powder are vasodilators that can cause gun headaches, "especially in individuals not habituated to them."

As a kid of 10 or 11 I had one of those in the english stocked - no pad - ul 20 gauge models.

Kicked like a damn mule.

How far off the lands are you seating them?

(Thanks for the info)

I think you mean nitrogen oxides (and dioxide) - these are gaseous and termed NOXs. Nitrates and nitrites are not gaseous.

NOXs can inflame and damage the respiratory system over time - I don't believe they cause headaches or are present in signifcant quantities in burnt powder. I'm aware of lead causing more issues in poorly ventilated indoor ranges rather than NOXs.

I have a headache after shooting my 300 Weatherby several times.

I haven't shot anything bigger than a 308 in years. My main deer rifle is a 257 Roberts, followed by a 30-30 Marlin.

I did recently buy a new big bore, a 350 legend.

This is an interesting thread. I wear in-ear foam plugs and over ear muffs when shooting today. However, when younger, we didn't wear anything when hunting. Days in the field dove hunting were when I noticed it. I have found that after a day of that, I would come away with a headache, irritable and generally feel like I was in a fog. My ears felt like they had pressure on them. Sleep was the only thing that seem to help with it going away.

I still feel it today when at the range sitting beside someone that has a muzzle brake beside me. The concussion wears me down quick. Dividers between benches do not seem to mitigate it. From what I understand, your head takes the concussion even with ear protection on. It's just the way it is. I'd be curious to know if it's still felt after being behind a supressed rifle.

I have given up shooting slugs weighing more than an ounce in a fixed breech shotgun. You might find Brenneke K O one oz. a lot more comfortable and just as deadly.

I have a Shiloh Sharps #3 that weighs 12 lbs and has a shotgun buttplate. Loaded with 83gr 1.5 Fg and a 485 gr PPB about 10 rounds off the bench is all I can stand before getting head achy. Same with a 44-90 C Sharps built with the express type stock (straight and pistol grip). Its not the recoil so much I think...its the blast.

Never will understand how soldiers could endure the blasts of heavy artillery.

I wear plugs molded by my Audiologist buddy who also shoot a lot.

3-4 rounds of skeet w/12 or 20Ga doesn't seem to bother me at all.

50 rounds of 243AI shooting 105's from a 16# rifle/scope for an F-Class club match and I've got a headache. Same for 13# 308 shooting 155's. My shoulder doesn't really bother, just a headache. Neither rifle has a brake, nor do any of my hunting rifles, 1 Interarms 375 H&H that I never shoot and a few AR's w/flash-hiders is about it for brakes. Almost all of my rifles have 20"+ bbls.

Prone shooting gives me a headache much much quicker than shooting off of a bench or standing/off-hand.

I don't have any diagnosed neck/back (or any other joint) problems beyond being a few months shy of 50 and overweight.

OK, we can eliminate nitrate fumes from "recoil headaches" easily...next time you anticipate shooting the firearm that induces the headache...drink a generous amount of vitamin C in the form of orange juice, grapefruit juice etc...before, during and after the shooting session. Miners that suffer from dynamite headaches (and ammonium nitrate too) usually have 3 or more of those little juice cans in their gut bucket.
No headache? It was the nitro fumes. Headache? it was the recoil.

How about my thought experiment mentioned earlier: If it were fumes, why would a 243 not bring on the headaches while a 308 would given they burn about the same amount of powder?

We can also probably eliminate nitrate fumes from Eileen's recoil headaches, because they always start to after shooting maybe 2-3 shots outdoors--with the rifle's muzzle pointed away from her, naturally.

Now that is interesting.

For me, it's anything more than, say, a .308 shooting a 165 at about 2700fps with a rifle weighing about 7 lbs. More than that and I have a headache after about 5 rounds.

Someone in Oz read Gough Thomas' book, too.



https://www.claytarget.com.au/joomlatools-files/docman-files/CTSN/1990/1990_V43_12_Dec.pdf

https://www.mayoclinic.org/diseases-conditions/traumatic-brain-injury/symptoms-causes/syc-20378557

There certainly may be other contributing factors like the airborne nitrates theory, but what you're describing above is a textbook list of symptoms from minor TBIs.

I'll jump in and add my .02 cents: I'll be 88 next month and my big game rifles are mediums and a big bore. I handload for each and have for over forty years. I don't own a small bore except for a couple .22 LRs. Usually one goes with me to the range for practice of trigger control and a break from heavy recoil. I settle on hunting loads (handloads) for each BG rifle, practice a little with those loads and get away from the bench. And for my .458 Win I've settled on a reduced load for a relative light bullet - a 250gr MonoFlex (no lead) at 2700 fps that's very accurate and holds onto 94% of unfired weight in very tough test media. It's my bear load that makes 24 ft-lbs recoil (and the rifle has Mag-na-porting). I also sit up straight at the bench (no slouching) allowing my upper body to move with the recoil as in offhand shooting (which I also do in the woods of Gov. property). And I hold down on the fore end of the rifle to keep it from bouncing off the rest so it comes straight back.

Then, for all those rifles (.35 Whelen, 9.3 x 62, .375 H&H) I shoot full house handloads using magnum PAST shoulder protection, PLUS either a folded up terry-cloth towel OR (now) a 2" thick piece of dense rubber foam cushion (cut from a tree stand cushion) to fit over or under the PAST protector (Got that idea from Dr Ron Berry who shoots a lot of full house .458 Win Mag). In other words, I protect for the jolts to my shoulder that's connected to my whole body. Extra ear protection helps with the nervous system by telling it the recoil isn't that bad after all. Most of my life I've been shooting magnums and Big Bores and see no need to quit yet with proper management of recoil through: weight and fit of rifle, particular handloads for the game in question and getting off the bench when the rifle's ready to hunt. Once I have the load for a particular rifle, I'll test it for accuracy at the bench by shooting no more than about 8 to 10 rounds per session. And at this stage in my life, I try to keep all loads under 40 ft-lbs recoil if possible.

Bob
www.bigbores.ca

My Savage 20 gauge bolt action slug rifle is very light and has a very nasty recoil even my 458 Lott kicks less , so if you want a headache try shooting my 20 gauge slug rifle its a 3 inch 260 grains of lead slug. Pete53

Recoil can do it. So can muzzle blast. I cannot be anywhere near a muzzle brake. Having had many concussions recoil/blast headaches are a main priority for me at the range. Calling blast or recoil "concussive" is 100% accurate.

i never understood why someone needs a brake for hunting big game ? even my skinny little adult daughter does not feel the pain when she has shot her husband`s 7 mag. at a deer.

I never understood why someone would not use anything available to mitigate recoil and noise in a firearm. Even real men and women shoot better with less recoil/muzzleblast and it is much more enjoyable. Neither hair cell (in ear) nor retinas can be strengthend through machismo. Headaches are not awesome, either.

I have gotten them sighting in rifles for other people. No idea, if it was the recoil, the fumes or whatever. All I know is, my silenced .308s with 130 TTSX will kill anything I might shoot at and I get to do my part :-)

Honestly never understood that reasoning. Rifle should be shot way more often than just at game.

Lifelong allergy/headache sufferer.
.300 winmag was sometimes tolerable.
Other times gave me a wicked headache.

Im older now and won't even chance it.
Lighter kickers for me.

Haven't had a migraine for years (knock on wood).
But last 4 days have been blah.

I never liked amusement rides either.
Snot slosh is a thing LOL

Interesting topic. jack O'Connor addressed the problem in one of his books. I think it was, "THE HUNTING RIFLE" where he thought some people had their brains addled by the hard kicking rifles, He opined that the recoil gave the shooter a mild concussion.

Over the years I've shot many rifles chamber to various cartridges ranging from the .22 Hornet to the .416 Rigby. Frankly, the only one that has ever seriously given me a problem is/was the .338 Win. Mag. I never shot some of the bigger rounds much so I don't remember if I had problems with them.

The only way I can describe what went on when shooting the .338 is the rifle fires, I feel the recoil but hear/feel a sharp clicking sound inside my head. Instant headache. I think the recoil effect is such that my body is literally snapped back and forth in a rapid manner and my brain bounces back and forth in th process.

It has been said that as one ages, the brain shrinks a little as the years go by. That probably aggravates the situation. Hell! What do I know? anyway that's what I think happens when one shooting something with substantial recoil. Probably why I've been working almost exclusively with the 7x57.
PJ

I was at the range with my son Sunday helping him knock the dust off his rifle shooting skills (he's an occasional deer hunter but fanatical waterfowl hunter), we were shooting suppressed 308s. There were boomers on our left and right and I went home with what I call a percussion headache. I don't think it's from recoil and we were shooting suppressed with good hearing protection. I'm convinced it was our shooting neighbors but can't say for sure, it happened last time I was there too!

Mule Deer, I'm wondering why Eileen has not had a rifle fitted with suppresser yet? I tried my first last year and I now own three, won't hunt without one, my lonely Model 70s never leave the safe these days!

A few years ago I shared the range with a 30-378 Weatherby shooter. His rifle was equipped with a Swiss cheese muzzle brake and the report was obnoxious. I was using plugs and muffs, so it didn't sound as loud but the pressure wave moving down the firing line was like a slap to the face and I could feel it in my sinuses.

"Really the best case scenario is to wear both "over ear" and "in ear" when shooting anything big."
I have been wearing double ear protection for years due to my fear of losing hearing, when I was growing up and until early twenties didn't care much but now I do, I also use Caldwell shoulder strap pad when shooting to protect the shoulder.

You don't have to be knocked unconscious to have a traumatic brain injury. Mild TBI's can become cumulative, can cause issues over time. People so disposed can become more sensitive to repeat physical insults.

I think you have to listen to your body. If recoil causes headaches, it's trying to tell you something.

Engineering around physical problems is well known in industry. Gadgets can often be designed to relieve employees from situations or functions that can cause physical problems or injuries.

So, as is the accepted process in industry, we should work to "engineer" our situations to minimize symptoms caused by known irritants.

As described by many, with recoil headaches you cut down on recoil, blast and noise to a comfort level you and your body can live with.

Then, one would think with less kinetic energy, less power, less blast, one would have to become a better marksman. Go figure....

There are a number of Fire members who have described dropping a power level or two for their everyday hunting ordinance based on a number of issues.

Sometimes less is more.... Just depends.

Speaking of, your president, asked by a reporter if he wore briefs or boxers, thought for a moment then answered, "Just Depends"....

Whoops....

Yeah....

DF

I was at a range years ago, two guys posted up to me on my left, they were shooting a Browning BAR in 338 WM with a BOSS brake. My teeth literally hurt when they launched a projectile from that blue metal and wood travesty. To make matters more fun for me, the hot brass from the BAR auto came slinging onto my bench and sometimes on me. They solved the problem with the non-shooting friend holding a metal trash can lid using it as a shield to block brass from landing on me!

The discussion about fumes is interesting. Sometimes I touch off a few rounds out of my office window. Center fire revolvers in particular, even very light .38 special loads, tend to give me a lingering headache if I dont hang the gun out the window.

A while back I read about folks getting headaches from cooking certain smoked meats….I used to get them when I would fry bacon- we now cook it in the oven. The headaches are very similar.

Soooo….I guess in true campfire fashion….someone asked about recoil headaches and the solution is to put some gunpowder on your hard hat and quit frying bacon.

If I had to quit frying bacon I'd be very sad.

You pilgrims don't know beans about concussion until you see the grass flatten 30 yards in front of the revetment every time 'Long Tom', 155mm M-2 goes off. Makes it easy to catch grasshoppers.
And another thing, put a pinch of double base powder between cheek and gum and rub your hardhat band with bacon grease for all day satisfaction. I gots other medical advice too, jus' axe me.

Yeah, you can see why African PH's hate muzzle brakes.

I have one rifle with a brake. It's an Ed Brown Damara in .300 Win Mag. Ed said his light weight magnums shot better groups with a brake and he may be right.

I was shooting this rifle on a bench. There was a piece of paper lying near the muzzle. The blast shredded that piece of piece of paper. Amazing.

DF

So a question for the experts, and this may deserve its own thread. If a person was going to build a few rifles to shoot that wouldn’t cause the headaches what would be the top choices? I’ve been hating recoil more and more but still enjoy shooting and would like to have my kids do more of it without the side effects.

It depends on the kind of shooting you'll want to do. For example, if you like to clang steel a fast twist 223 will reach out pretty far yet have very little recoil.

I would be interested to see if anyone experiences recoil headaches when shooting handguns.

With enough blast and noise, maybe.

But I would think rifles would be more of a problem for those guys, especially big, bad ones.

DF

Could you speak up a little loader, I didn't get what you said.

Ha!

You say something?

DF

Did I hear a soand somewhere?

The first Shiloh Sharps model 74 I ever bought was a 34" std octagon barrel long range express chambered for 50-140 3 1/4" inch. The load at the time was 140 grs fg and a 560 gr paper patch bullet running over 1500 fps in a 10 lb 3 oz rifle. Recoil.was rough plugs and muffs and a Buffalo Arms prone model recoil shield were and are an immense relief. Roll with the recoil 1/2 doz. shots are enough anymore for me. Aren't alot of them left most have been rebarreled to smaller cartridges. Shooting should be fun not beating yourself up. I allways take my Xtra strength Tylenol up front about a half hr or so before shooting it...mb

Apparently you dont read through replies.
In my only reply, I said it happens with 44magnum.
But it also happens with full house 357mag, and 45 colt.
I have sold all my big bore handguns as I cannot shoot them

I never had a problem with headaches shooting my handguns. Shot a lot of .357 mag and .44 Mag for a while but nary a headache.
PJ

One of the interesting things about Eileen's recoil headaches is she doesn't get them when firing her T/C Contender .357 Maximum, which recoils quite a bit--but isn't as noisy as a revolver due to lack of the cylinder gap.

The Textbook of Small Arms, 1929 [Great Britain War Office], gives a recoil velocity of 15 ft/s for 6-7 pound shotguns as having been "long established as a maximum above which gun-headache is sure to ensue."



PS Also ran across an interesting recoil calculator website with a Barsness' index.

http://kwk.us/recoil.html

That's interesting! I made a chart this week of different load / rifle combinations that I've shot (that I can remember), and the combos that keep the recoil velocity below 15.5 don't seem to give me headaches.

Buddy said my 180gr jhp .44 mag load ( Layne Simpson WW 296 load ) was the most annoying thing he ever shot.
Seemed worse when launched outta my 8 3/8 629-3.

Definitely swats the ol sinuses LOL
Indoors it knocks ya silly.

JUst watch a slow-motion of someone shooting......I always get headaches

Thanks for the snippets and links.

The aussie article simply references the original article so is not additional evidence or finding - he's just perpetuating the idea.


There's nothing else to support the production of nitrates and nitrites from burning nitrocellulose. The original article is a leap of faith connection made by someone without any expertise in the matter ie making something up.

https://www.sciencedirect.com/topics/medicine-and-dentistry/gunpowder

Gunshot Residue

GSR consists of unburned or partially burned gunpowder particles, soot, nitrate, and nitrites from the combustion of the powder, particles of primer (oxides of lead, antimony, and barium), and particles of the bullet or the bullet jacket that are vaporized when a firearm is discharged (Rowe, 2000). They are projected from the barrel in a conical cloud; and they are also expelled from the various openings of the weapon such as the chamber, the ejection port, and the slide action.

An old remedy appears to have been holding a rubber band between the teeth. . . .

Interesting. Looks like the nitrites come about from incomplete combustion.


Semms that CO can cause headaches, but I doubt there'd be enough generated by small arms ammunition:

"Toxic effects of gunshot fumes from different ammunitions for small arms on lung cells exposed at the air liquid interface"

https://www.sciencedirect.com/science/article/pii/S0887233321000205

(Headaches are mentioned in section 1)

Interesting topic. I've known trap shooters that get recoil headaches. I've never had a recoil headache to my knowledge but kept my magnum phase limited to about a 10 year period. My main hunting rifles now generate 25 ft/lbs or less of recoil, mainly because they all weigh 7lbs or less. If it were me I'd be done with recoil headaches and anything that caused them. Your body is trying to tell you something......

That dang rifle blows my hat off each time I fire it, gets alot if gas in the face. Been meaning to put another muzzle break on it but haven't fired it in over 20 some years so out of sight out of mind

I shot my 300 Weatherby a few times yesterday to set a new scope I mounted on it. I wore ear muffs but it still gave me a slight headache. It always does.

Remington factory installed muzzle breaks sucks

I notice some skirting around the possibility the headache is concussion caused .

In the first few pages there was some pretty firm opinions that it was concussion causation. I didn't intend to upset the apple cart by suggesting exposure to nitro particulates causes headaches...I just mentioned the possibility. Anybody who has ever done any blasting in mine, pit, roadbuilding or quarry will confirm. Of all the hazards in shooting, personally, I would fear detached retina more than anything and thusly avoid hard kickers.

Its not a cure all but when I was shooting 416s and 458s regularly for my job I used a mouth guard like what a football player might use. The kind you boil in water then form to your own teeth while it's still warm.

Seemed to help and it was a permanent part of my going to the range kit.

To further muddy the waters....when in the vicinity of artillery, the Army drilled us to use issue earplugs and hold our hands over our ears contacting the mastoid bone firmly with the thumb pad, and leave the mouth slightly open. Definitely pressure wave concussion in that case.

I never had the problem until after I had a concussion.

Valid observation. Concussion is a traumatic brain injury. TBI’s don’t have to be severe with loss of conscious to cause issues. Seems the trauma can be cumulative. So, more injury, more susceptibility to repeat injury, more sensitivity.

I don’t think the concussion component has been played down that much. It’s definitely part of the equation, although other issues may contribute.

DF

I get a headache just thinking about ever shooting a 378 Wby ever again............most wicked, quick, vicious recoil imaginable.

I have no magnums left in the stable save for DG, just don't nèed them for non-DG.

My range sessions are much more pleasant since.

MM

The .378 also has one of the quickest "recoil velocities," meaning the acceleration of the rifle upon firing--which can even be more important than recoil energy.

The other factor, of course, is whether the rifle's scope hits your head. This may seem obvious but 30 years ago was in Germany on a writer's tour of the then three Zeiss factories. One stop on the week-long tour was an indoor shooting range, and because Zeiss had been criticized (with some justification) for the recoil-resistance of their scopes back then, one of the rifles including was a .416 Rigby with a lower-magnification variable.

The Zeiss folks invited all of us to shoot the rifle, but many passed, including both me and Jim Carmichel--since we'd already shot .416 Rigbys. But one of the others, an older guy whose name I can't remember, puffed up and said sure, he'd shoot the rifle. He shot offhand (the least obnoxious way to shoot a hard kicker), and the scope's objective bell whacked him in the eyebrow hard enough to make him bleed, even though it had a rubber ring around it. He bled a little, and somehow insisted it hadn't hurt him. (Eye relief was often very short in many Euro-scopes back then.)

Nobody else volunteered to shoot the .416, which isn't surprising.

People are different.
The MSG in one Dorito snack chip will set off a migraine in some people.
Likely same with the whiff of gunpowder fumes, nitrates and nitrites in food also cause migraines in some.

I suspect it is a cerebral vascular sensitivity to various stimuli that causes the "gun headache."
Concussive sound waves transmitted to vessels in head might be a trigger too, in some folks, not all.
The full blown "concussion syndrome" of brain bouncing off skull need not occur to get a gun headache.
But if it does occur, some folks are more susceptible to that too.
The outsides of our skulls are different.
Some of us have a pronounced inion at the back of the skull, a bony prominence, feel it when petting your favorite hound.
Other folks have smooth skulls at the back.
The pseudo-science of phrenology read bumps on the skull.
Maybe insides of skulls are different too.
Some skulls handle brain bounce better.

I only got gun headache from the likes of +.50-cal sporting rifles and the 12ga From Hell 3.85" rifle with 1400-gr slugs at 1400 fps (no brake) to 1800 fps (with brake),
Those are also the guns that caused a mild electrical shock sensation to run down my arm, from shoulder to trigger hand.
That one is easy to explain as a love tap on the brachial plexus nerves in the shoulder,
not as painful as a "funny bone" contusion of the ulnar nerve.

I am lucky in just not getting headaches.
The only other times I can think of mild headaches I have had is after a punch to my face in a boxing match made me suddenly sit down hard on my butt.
Fight was over, I was 17 y.o. and have not boxed since, just don't have the speed some do.
I am a slow-twitch endurance athlete type.
I am proudest of 2 miles in 9:25 at age 18 y.o., back when I was an inch taller and 60 pounds lighter.

Also, I tried learning to ski at 60 y.o. Bad idea. Bouncing my helmeted head off the ice one time was enough.
Had a mild headache for a few minutes after that too. Never tried skiing again.

Now the real funny:
Mr. buckstix once argued that a steel plate on a shotgun-style butt was excellent on a hard kicker, better than any recoil pad.

I am calling out Mr. buckstix on that. Wrong.

As Bob Mitchell noted, a benchrest pad of high-density foam rubber, cut from a deer stand seat cushion,
would work well on a .577 Tyrannosaur with a steel butt plate.
I use such a sissy pad for benchrest shooting.
The extra LOP it gives also prevents Weatherby Eyebrow, at the benchrest.
Accept the scope's ER and tunnel vision at the benchrest.
Learn and live.

It is having your .450 #2 Nitro Express double on you. That will rock your world

One of the interesting things about doubles "doubling" is the recoil energy is actually four times as much instead of twice as much.

It would be twice as much IF the gun weighed twice as much--but the gun weighs the same, hence the 4x recoil energy.

In general the 9.3x74R, like it's cousin the 9.3x62, is considered a relatively mild-recoiling round for a medium-bore. But I had an 8-pound 9.3x74R side-by-side double for a few years, and one day it doubled when shooting at a target. It felt more like a friend's .505 Gibbs....

A 460 Weatherby was the rifle that made me cry uncle. The owner casually said to me before I tried it "This is the only rifle I have that kills on one end, and maims on the other". I thought he was kidding. He wasn't.

I'm not a stranger to big bore rifles, with a 375H&H and a 458WinMag in my safe, but that Weatherby was just mean...........

Yes, it gave me a headache, a shoulder ache and a sore neck.

Townsend Whelen had the recoil velocity at 15.4 ft/s, which is pretty close to your number!

Catching the scope between the eyes has always worked for me- several times.

30 rounds from my 458 Lott makes a ring.

I believe it was Carmichel that tells of a PH that used a 460 cut down to 18”. Said it was a real joy to be around when it went off!

In my son's senior year he suffered a massive concussion in football, kid he was tackling ducked his head, they met helmet to helmet it was just one of those things that happen. The other kid staggered abut four yds back and popped back up. My kid dropped like a wing shot quail, out like a light for 15 min. Before the "hit" my son shot a lot of heavy waterfowl loads in 12 gauge as in 3 1/2" . After the "hit" he has downsized to 20 gauge. When I asked him about it he said the "big loads" hurt too much, I asked if it was the shoulder, he said no, I get headaches after two or three shots. He used to shoot my Red Hawk .41 mag, now it gives him headaches as M.D. alluded to due to the barrel cylinder gap concussion. So, I have little doubt that heavy kickers do cause physical injury, and furthermore what is defined a heavykicker is totally the perception of the individual shooter.

You make a great case for cumulative TBI and how that can change one's sensitivity to recoil and to subsequent, even milder insults.

It does change the equation and folks have to adjust to their new tolerance level for recoil, noise, etc.

In essence it's a reset of the baseline of what's tolerable and what's not. We need to listen to our bodies...

DF

4 bores can cause them.
4 bore in action by .com/photos/156296479@N08/]Steve Zihn, on [bleep]

These days since a bad car wreck have pretty much kept me away from shooting anything. A while back I retired most of my harder kicking rifles and have been playing with the 7x57 load to 7-08 levels. In fact, on Jan 2, 2020 when I had my accident, I was on my way to the range to do a final check of the sights on my Winchester M70 7x57 using the 150 gr. Nosler Partition as my elk load. I did plan to also take my .35 Whelen as back up in case pf problems with the M70. Best laid plans.
Probably the cartridge that has hurt me to most is the .338 Win. Mag. I have a .375 H&H, .404 Jeffery and .416 Rigby Ruger #1 rifles that are more or less retired. The two .338 Win. Mags I have are a post 64 M70 and a stainless classic. Either rifle literally slams me back and forth and I hear a "click" inside my head. After a very few shots I get a vicious headache that takes hours to go away. FWIW, the click sounds a lot like a small branch being broken in two. Dunno if that means anything but it tells me to stop shooting that .338 Win. Mag. The Stainless Classic has a 26" Barrel plus 2.5" of muzzle brake and recoil is no different that the 24" barreled post 64 gun. I have no problem shooting an M70 26" barreled .300 Win. mag. Haven't quite figured that one out yet.
Looks like if and when I start shooting again, it'll be stuff like the .223 Rem.,.243, 7x57, .308 and maybe the 30-06. They've never given me any trouble regarding recoil. I'll limit the .35 Whelen to check shots and an actual hunt should I do another elk hunt. I have given thought to the 7x57 as promary and the 30-06 for back up for the elk unt as I usually just go for a cow for meat.
PJ

I sometimes get headaches when shooting harder kicking rifles. This is especially true if I have any sinus congestion when shooting. My M700 KS 338 WM is one of my favorite rifles, but it's a no go for me if I'm just a little congested. 1 shot and my head will start to throb, and really hurts by the 3rd shot. My 300 Weatherby and 375 H&H does the same.

One of the reasons my purchases in recent years have been smaller caliber rounds and none of the Uber magnums like a 300 RUM or 28 Nosler.

A light weight .300 Wby can get one's attention. I shot a 500 Nitro Merkel double, helping a good bud get ready for Africa. Big push, to me not that punishing. And, Merkels from what I've read, are knowns for doubling. Glad this one didn't. I sighted in another bud's M-70 .416 Rem, again in prep for Africa. It was a push, not that punishing from a standing bench. I was able to shoot around an inch at 65 yds, two shots, (not 10...!). And, I had shoulder surgery a few years before on that shoulder. I sent a video to my surgeon, who is also a hunter. He got a chuckle out of it.

With the 500 Nitro, I hit a target at about 35 yds, put the second bullet within a couple of inches, both shots off hand. I got the feeling I could control either gun well enough to do what needed doing. I hunt Africa vicariously, no plans to go.

DF