Thread 63973081

Can someone please explain to my retarded ass how guns shoot cooler with polymer cases?
Wouldn't metallic cases shoot cooler because they leech more heat out the chamber over time, versus polymer?

>>63973081 (OP)
Anon:
It doesn't. They're cheap to manufacture and they're light. Otherwise they're shit, but companies will sell any lie someone will buy.

>>63973094
>>63973081 (OP)
Have you retards not heard of the concept of insulation?

>>63973081 (OP)
How much lighter are these. Are they available in bulk? How bad is it for my rifle to lose the ability to dump heat from shell casings?

>>63973099
i don't see cotton candy in them rounds
why ain't my cpu covered in insulation then?
>>63973100
>How much lighter are these.
a fair amount
they're better for when you're using 30+ round mags & belts
a gi mag with them would be comfy to carry for a long trek though
>Are they available in bulk?
anything is, assuming you have money
>How bad is it for my rifle to lose the ability to dump heat from shell casings?
thats the thing, its apparently not an issue, as barrel temps are cooler off them

>>63973112
>its apparently not an issue
Heat build up is always an issue. Machine gunners don't haul around extra barrels for no fucking reason.

>>63973115
yeah?
and when they used polymer cased ammo, they didn't have to change barrels as much

>>63973119
Can you cite an evaluation from any military that found that?

>>63973081 (OP)
>Can someone please explain to my retarded ass how guns shoot cooler with polymer cases?
The polymer doesn't transfer heat from the powder burn inside the casing to the chamber. The gun really runs much cooler until heat from the rifled portion of the barrel ( which isn't insulated, and sees the hot gases, as well as friction from rifling engagement) starts transferring to the chamber.

>>63973125
So it doesn't shoot cooler.

More heat is transferred to the barrel versus the receiver, reducing long term sustained fire capabilities.

>>63973136
Can you not read? It does.

>>63973137
>More heat is transferred to the barrel versus the receiver
The receiver gets a comparatively negligible amount of heat, fuckface,

>>63973081 (OP)
The polymer rounds insulate the chamber from the hot gases produced during firing whereas brass rounds conduct heat, letting it transfer through to the gun.
What's not to get?

Note that it specifically says heat transfer to the chamber and bolt face. Not sure it'll make a significant difference to barrel temps.

>>63973144
i don't think he even owns a gun, so you're not gonna get him to understand shit anyway

>>63973150
Summer /k/ really is the worst. Europeans have too many summer vacation days.

>>63973147
Noshoots.

>>63973148
If the hot gasses dwell at hotter temps in the chamber, it will make the barrel hotter as that is the only way out of the gun.

>>63973158
>the hot gasses dwell at hotter temps in the chamber
That's not how it works.

>>63973162
If the heat can't transfer to the chamber through the brass, it doesn't go away anon.

>>63973156
I shoot full auto regularly. You?

>>63973164
post timestamp with fire control

>>63973164
At your airsoft matches?

>>63973112
>why ain't my cpu covered in insulation then?
Because you want to cool your CPU and not insulate it. ie. you want to let the heat out into the atmosphere from your CPU.

With cartridge cases you want to keep the hotness inside the case, so the gun doesn't become hot, until it is thrown out of the gun.

>>63973158
Uhh have you heard of ejection?

>>63973163
Yes, it does, by virtue of the gases venting forward of the case mouth.
You're assuming that chambers just happen to "get hot" and must be cooled by the brass acting as a heat sink. That's only true once the chambers are hotter than the brass that's being ejected. Until then, chambers warm up specifically because hot brass is inside of them.

Heat transfer isn't a one way street.

>>63973167
It's Saturday, but I can do it on Monday if the thread is still up.

>>63973170
I'm in the US. None of that euro kiddy cringe. Nice projecting, though.

Today anon posts a thread to start arguments about polymer cartridges and the well known fact that they increase heat in a firearm as they cannot pull heat out of the system when ejected like a brass or steel cartridge can.

>>63973185
>dude trust me, i'm totally a navy seal bro
oh yeah? and you need pictures of my asshole too, don't you?
not falling for that shit again

>>63973187
>they cannot pull heat out of the system when ejected like a brass or steel cartridge can
Polymer transfers less heat to the system in the first place. It's really not that complicated.

>>63973158
Do the gases sit in the chamber or do they get blown out into the atmosphere, taking the heat with them?

>>63973192
How much heat does it transfer in the split second before the cartridge starts to get pulled out?

>>63973417
42.

>>63973081 (OP)
You've got a plastic cup in your left hand and a metal cup in the right. Boiling water is poured into each cup. Which hand feels hotter?

The same heat is in both cups. It just leaks more slowly from the plastic cup, so that cup feels cooler. Both hands will ultimately absorb and dissipate the same amount of heat, but the reduced convection of the plastic cup gives your hand more time to dump that heat without being damaged.

>>63973192
The reduction in heat transfer is probably like 1%. Most of the heat in a firearm comes from pressure and friction, not flame propagation.

>>63973417
Depends, some systems open up faster than others. Piston guns open up really fast compared to DI. Probably in the double-digit joules per round, I would guess.

But if you want a quick proof that polymer rounds transfer less heat to the chamber, just skip to the end of this:

https://www.youtube.com/watch?v=0G_FSmpaeVo

Past that, barrel heat will eventually transfer to the chamber, but that depends on overall barrel heat capacity (mass), etc..
There are some polymer rounds used in machine guns in a military context, so make of that what you will.

>>63973081 (OP)
Surprising nobody, it turns out it's very difficult to make plastic reliable in high load uses.

>>63973451
> friction
yes, but that happens in the rifling, past the freebore, not in the chamber itself
>pressure
Pressure is roughly linearly related to heat, and it would drop the same whether it's a brass or polymer case. The gases detent the same. The differential is in residual heat.
Pick up a brass case that has just been fired, it's very hot to the touch. A polymer case, not at all. The chamber sees the same thing.

>>63973474
The way barrels whip under recoil is what generates heat. The chamber is a part of the barrel no? Like I said 1% reduction.

>>63973492
You're wrong. This is like saying that if we start a fire a the fireplace, and we mitigate all that roaring hear from the burning logs, it won't help because the the smoke will warm up the chimney a little. Like yeah there's some hear there, but you're fucking retarded if you think that the source of the heat being isolated does nothing.

>>63973094
It's illegal to lie in advertisement.

>>63973512
I watched the video you posted, the barrel was the same temperature, the chamber temperature was different. It probably extends barrel life because it’s a light powder charge with efficient internal case geometry.

>>63973492
>The way barrels whip under recoil is what generates heat
Absolutely fucking not.

I asked ChatGPT to settle this once and for all

Myth 1: "Brass acts as a heat sink"

Yeah, it does—but that’s not a good thing in this context. Brass transfers heat into the chamber and receiver, not away from it. When a brass case expands, it makes solid contact with the chamber walls and conveys heat into the gun, especially the bolt and barrel extension. That's where your lugs and locking surfaces are—aka places you don’t want excess heat soaking in.

Polymer insulates, meaning:

More heat stays in the case

That heat leaves with the ejected round

Less heat goes into the chamber and bolt face


This is exactly what you want in high-rate-of-fire weapons, which is why LSAT (Textron’s Lightweight Small Arms Technology) and True Velocity have been investing in this kind of tech. The U.S. military wouldn’t be experimenting with polymer cases if they were thermal time bombs.


---

Myth 2: "The barrel is taking more heat now!"

Okay… even if this were true (which it marginally is):

The barrel is designed to absorb and radiate heat.

It's got mass, surface area, and is replaceable on LMGs and some DMRs.

You don’t cook off rounds from barrel heat alone unless you’re really doing something stupid. Barrel heat isn't the limiting factor for most guns—chamber heat and bolt temp are.


And let’s not forget: barrels already get smoking hot in sustained fire. That's why MG crews train for barrel changes. That’s not new.


---

So why the hell do people say this?

Honestly? A combination of:

Misunderstanding basic thermodynamics

Parroting half-baked forum theories

Fear of change from traditional brass

That one time a prototype polymer case did fail and melted (which was an early-gen issue, not universal)

>>63973123
Sure, the SOCOM tests of True Velocity ammo for their helicopters.

>>63973115
And other lies O-2s spew out

>>63973081 (OP)
someone find and post that video of cappie sticking his finger in the chamber of a 240 after putting 50 of these rounds through it

>>63973081 (OP)
TV not getting the contract and thus putting polymer cases off for another 20 years is a massive setback to the market. These are objectively better designs from both a manufacturing perspective and a end user perspective

>>63973185
Euronegroidians arent allowed full auto airsoft guns. They cant even put lights on them.

>t. AmeriBVLL stationed in g*rmony

>>63973708
>Euronegroidians arent allowed full auto airsoft guns
Huuh yes they are. Whatever you're seeing in Germany doesn't extend to the entire EU.

>>63973642
>I asked ChatGPT
I'm on your side of this argument, but seriously, fuck you for bringing this cringe shit in.

>>63973722
>nuh uh we can have full auto toys
the tourist cope is unreal at this point

>>63973136
Right, it just dispels heat much better than traditional brass or steel case does.

>>63973722
so do you have one?

This shit is like the bodybuilding.com thread of gymbros arguing about how many days there are in a week, holy fuck.

>>63973779
>he really thinks theres 7 days in a week
explain why friday & saturday are greyed out then, retard

>>63973738
What part of "I'm in the US. Airsoft is euro kiddy cringe" do you not understand?
>>63973771
No, but his point about Europeans airsoft guns not having full auto is bullshit.

>>63973825
It’s not bullshit. Had to sell my stuff to come here because of your niggerfaggot laws

>>63973860
>It’s not bullshit
Show me where in the Czech, Italian, French or Polish law full auto airsoft is illegal

>>63973708
>Euronegroidians arent allowed full auto airsoft guns. They cant even put lights on them.

Top kek the 11B chilling at Ramstein thinks Germancuck laws are actually European laws!
Why don't you stop talking about shit you know nothing about and and "lose" some more PEQ-15s instead so I can get another one for the M4gery, lil' nigga?

>>63973081 (OP)
The heat doesn't come from the chamber, anon. It comes from the powder inside the cartridge. A polymer cartridge insulates the chamber from the heat of the burning powder.

>we need MORE plastic in our wilderness, oceans, testicles, bloodstreams, and brains
No

>>63973081 (OP)
fake and gay and only useful for openbolt mgs
they should just switch to steel case if theyre worried about muh costs n shiet

>>63973136
The chamber of the gun is what heats up the fastest and is where overheating causes issues first, so yes it functionally runs cooler.
>>63976657
Anon we are still fighting by throwing pieces of lead at each other, not to mention fucktons of other toxic and environmentally destructive stuff. Besides, who's to say that these can't be made with biodegradable polymers in the future? Being able to pick these up with magnets also helps with cleanup.
>>63976552
>M1 Carbine and M1 Garand
Where did the European market get these, American import or surplus from European militaries?

>>63976766
>Where did the European market get these

Absolute assloads of these were left in Europe after WWII and the decade right after.
IIRC hundreds of thousands of them served in Italy and France, also Greece, Denmark, West Germany, Austria or Norway.

>>63976766
>Anon we are still fighting by throwing pieces of lead at each other, not to mention fucktons of other toxic and environmentally destructive stuff. Besides, who's to say that these can't be made with biodegradable polymers in the future? Being able to pick these up with magnets also helps with cleanup.
Just because we use one toxic substance doesn’t mean we should add another. Also biodegradable polymer just leeches into the water table. It never really goes away. I honestly hope we can switch to copper bullets completely.

>>63973708
ami go home

Polymer case is a meme. I have a better idea. Use NAS3 cases, with their slightly higher internal volume, and load them to a higher pressure. The price is a slight weight penalty over polymer case 5.56, but a NAS3 5.56 at ~70kpsi is pushing 1500ft*lbs.

For reference, the 5.56 NAS3 case weighs only 60gr (4g) compared to 90gr (6g) for brass case.

Anyone know what the polymer case weighs?

>>63976887
Fuck off kraut, Ramstein "fell off a truck :^)" is how I get all my STANAG mags.

>>63976854
You do know these rounds have a magnetic steel base to make clean up even easier right anon?

>>63979255
Let’s be honest, 95% of gun owners don’t clean up their shit.