Why do ARs Eject Ultra-Hot Cartridges?

[jelenko]

Hmm. I've been shooting an AR 'across the course' since 1992 and am fully aware of the temperature of ejected brass.
But, this thread got me to wondering just what/when the brass gets heated more than a bolt gun.
I'm assuming it's during the ejection process - but when? I'm assuming the case is isolated from the gas being used to unlock the bolt until the bolt has retracted. If so, the heating would happen just after the bolt has unlocked and the case is ejected. Is that correct?

If it is, that gas has to be pretty hot [much hotter than the brass to heat it in such a short time]. But, where does that hot gas go? Except for an occasional puff coming past the charging handle, I never feel anything. And the occasional puff doesn't feel hot at all.

 

[dellet]

Simply the heat of firing. Extraction can happen before the case has time to release from the chamber walls, which is result of pressure and heat loss.

Rotational swipes on the case head are because the case did not twist with the bolt head. Over gassed systems have been known to have extractors pull off of the case head, or even pull the case head off.

So it’s not that it gets heated more, there’s is just significantly less cooling time before ejection.

 

[Laurie]

An ex-RAF (UK Royal Air Force) friend told me once of his first range-outing with the British 7.62mm 'SLR' (officially the UK L1A1 version of the FN FAL), our standard military rifle of the time during basic training.

The sergeant-instructor started the classroom instruction by saying this was the 'finest rifle in the world', then frequently contradicted himself by constantly comparing it adversely to its No.4 Rifle (Lee-Enfield that is) .303 bolt-action predecessor, so the trainee airmen hadn't a great deal of faith in the rifle by the time they got to live firing on a range.

What confidence was left went out the window within two minutes of firing commencing when an ejected case went down the back of an airman's collar and burned him badly enough to see him taken off for medical attention. After that, this group almost mutinied over further live firing training.

 

[SmokinJoe]

I think that ejecting the hot brass is actually part of the design strategy for keeping the weapon from heating up as much as would otherwise be the case.

On a lighter note: So this is the reason that it is highly recommended that women wear high neck long sleeve garments when around or firing semi auto rifles.

 

[joshb]

I think that ejecting the hot brass is actually part of the design strategy for keeping the weapon from heating up as much as would otherwise be the case.

On a lighter note: So this is the reason that it is highly recommended that women wear high neck long sleeve garments when around or firing semi auto rifles.

I have first hand experience with a gal that didn’t. Fastest strip tease I ever saw. Tho I felt her pain, poor girl, it was quite invigorating for me!

 

[nakneker]

I still have a 223 case scar on my inner right thigh. First and last time I ever wore shorts for Sitting rapid….

Unfortunately I’m a member of that club too.

 

[distinguished]

I still have a 223 case scar on my inner right thigh. First and last time I ever wore shorts for Sitting rapid….

At Quantico, I had one bounce off the leg of my stool and go down my shirt on the first round out of the second mag in sitting. Finished the string while it sizzled.
At Perry, a piece of hot brass from the shooter next to me landed between the corner of my shooting glasses and my left eye. When one eye starts watering, the other one does too. Tough to shoot 600yds when that happens. Tried to time my shots so I could turn my head away and it wouldn't happen again.

 

[Bill Clifton]

Immediate eject so no time to cool. If you think that is hot you've never had a black powder cartridge casing out of a lever action land in your shirt collar or on your hand when rapid firing in cowboy action.

 

[6Creed73]

Had a guy shooting an AR on the lane to my left. One in a thousand shot...a spent case landed on the back of my neck and down my shirt. Jumped up like a jack in the box trying to get it out of my shirt lol.

Still have a faint burn scar on my back.

 

[Earnhardt]

I think that ejecting the hot brass is actually part of the design strategy for keeping the weapon from heating up as much as would otherwise be the case.

On a lighter note: So this is the reason that it is highly recommended that women wear high neck long sleeve garments when around or firing semi auto rifles.

First part…huh?
Second part…yes.
But I would imagine having a brass shaped scar between the boobages, would make a great conversation piece…and give you a reason to stare a little longer

 

[L2R23]

A while back I remember seeing a product that was a soft rubber that had adhesive on one side and was attached to the shell deflector of an AR so the spent shells would not go flying off to who knows where. The add claimed they would pile up a short distance away. They were sold in multi packs. So I' m guessing the life span wasn't long. Might be a good product for range shooters.

 

[Rocketvapor]

For prone single fire I put a H3 buffer, cut gas back, cut ejector spring in the wife's AR for cases to just dribble out. A lot of them end up in the ammo box lid
They are still hot but not near a hot as fast ejected cases.

 

[MikeT49]

I was sitting on the left most bench on the 200 yard range. To my left about 10 yards away, was a guy with an AR10 on the right most 100 yard range bench. He shoots , a 308 case whistles past my nose, hits the walnut stock on the butt section of my rifle, puts a small dent in the stock. The case bounces off the butt stock, lands in my tee shirt pocket and burns my left tit. From then on I made sure that if a semi-auto shooters sets up to my left, either he or I puts up one of the ranges available, moveable, expanded metal ejected case shields.

 

[ncageneral]

I'd have to ask my neighbor as I was sending fired brass down his BDU jacket when we were at Ft. Sill, by the way he was acting it was hot tho. The nice drill SGT flipped his collar up after the first few rounds and told him to quit being a p****. Those fox hole firing pits either weren't spaced far enough apart or just right. I guess it depends on who you ask. He had some nice blisters.

 

[urbanrifleman]

Fire?

 

[jk80]

shell casings are preferable to hot slag meteorites burning certain parts of your anatomy while overhead welding, it truly is amazing how fast a human being can move sometimes...

Overhead stick stainless is the worst!!! Still have the scars to prove it. After awhile you learn that you're better of gritting your teeth and not squirm around cause you just get burned in multiple spots as it shifts around.

 

[SmokinJoe]

I don't shoot my AR's much but when I do I always put my shell catcher on the rifle. Don't expect that is practical for all situations but it sure helps out at the range. And, I don't have to chase down my brass afterwards.

 

[358WCF]

I have bought a windham weaponry ww-15 extreme varminter. I sighted it in a min and noticed the brass was hot like really hot anybody know why?

Just in case that person to your right at the range has a cold neck.

 

[PDS]

I remember some across the course service rifle shooters wore bib overalls to keep from getting a hot brass down the old butt crack .

 

[Fast14riot]

I have a TC Accessories brass deflector on my NMA2 that works well for just dumping them a short ways away. They make one for flat top to go under a scope base, too.

There is also the cheap method of putting the fuzzy side of velcro on the shell deflector to soften the bounce.

But, this is how fast it happens. I used the slow motion video to help diagnose a short stroking spare parts AR I built. You can watch the trigger release, then see the impulse from the shot, then gas and ejection. (Problem fixed now)