How to tell when you've been shot with a hot gun?

[Rogerborg]

Check out Code Red Airsoft FPS Calculator - shows Joules values etc for different weights and FPS

It's very handy, but what it doesn't show is how much higher your Joules will creep when you switch to a heavier BB, how much more energy a heavier BB will retain at any given range or how much more hurtier (sorry for the technical term) denser BBs will be even without Joule creep.

I've never seen it seriously discussed, but I'm wondering if there's a case to be made for limiting BB mass.  My CQB site already limits to 0.25g because denser BBs wreck the site.  I'm only just barely comfortable using 0.46g outdoors: I wouldn't be too upset if a site were to limit to 0.4g or even less.  If you spend any time watching sniper videos, you'll see examples of eyepro being shot off of people's faces by sniper BBs.

 

[BoomingHedgie]

Well to answer this question I would use this My own personal variation on the rule of 9’s chart we used in the army to asses burns .

View attachment 37262

Haha that is amazing!

Mummy! is the best one by far ?

 

[clumpyedge]

Haha that is amazing!

Mummy! is the best one by far ?

Pretty similar to the tattoo pain threshold chat... personally I've started handing out bitch mints to people that cant handle their hits..

 

[Adolf Hamster]

It's very handy, but what it doesn't show is how much higher your Joules will creep when you switch to a heavier BB, how much more energy a heavier BB will retain at any given range or how much more hurtier (sorry for the technical term) denser BBs will be even without Joule creep.

I've never seen it seriously discussed, but I'm wondering if there's a case to be made for limiting BB mass.  My CQB site already limits to 0.25g because denser BBs wreck the site.  I'm only just barely comfortable using 0.46g outdoors: I wouldn't be too upset if a site were to limit to 0.4g or even less.  If you spend any time watching sniper videos, you'll see examples of eyepro being shot off of people's faces by sniper BBs.

well it's still a work in progress but that's what i've been trying to answer.

if you take a look at the attached spreadsheet it shows the range of a bunch of different weights at a given fps, and you can set the MED as either an energy (ie how far before said bb hits with the same authority as a gun of said energy at point blank) or as a distance (in which case it tells you the energy)

it doesn't take into account joule creep although i have listed the energy values as the fps equivalent for a 0.2g bb just because that's a unit we're familiar with.

assuming i haven't made a mistake (+1 e cookie to anyone who finds one) the results are relatively interesting, as you can see i have it set for a site with a 350fps standard limit, a 500fps sniper limit, and a 20m MED for snipers and a sniper using o.5g bb's at the edge of his MED will feel like a normal player at point blank.

View attachment 37290

joule creep is a tricky one to answer, as it depends on a lot of complex factors ( such as how much blow-by of the bb there is, the pressure drop off as the bb travels down the barrel etc), the best i could do there is a very simple demonstration of roughly what's going on in a gas gun with a constant pressure supply but the creep values aren't going to be very representative of real life.

 

[Rogerborg]

a site with a 350fps standard limit, a 500fps sniper limit, and a 20m MED for snipers and a sniper using o.5g bb's at the edge of his MED will feel like a normal player at point blank

Going by the raw energy, yes.  But would you prefer to be poked with the sharp end of a pencil, or the eraser?

By the way, thanks for putting that effort in.  I'm going to send the kids off to bed, turn the lights down low, settle down with a glass of wine, and get my nerd on over it.

 

[Adolf Hamster]

Going by the raw energy, yes.  But would you prefer to be poked with the sharp end of a pencil, or the eraser?

By the way, thanks for putting that effort in.  I'm going to send the kids off to bed, turn the lights down low, settle down with a glass of wine, and get my nerd on over it.

true, i'm not making any claims about the effect of heavy/slow vs light/fast in terms of the terminal ballistics, although my preconception from what i've seen of real steel ballistics is that heavy+slow is probably worse.

no need for thanks, i've not been pewing recently and i desperately needed something to stop me tinkering with my guns (and likely messing something up), plus a refresher in the ol' excel is always handy.

 

[Game Cam]

This seems overly complex for the result of "if it hurts more than usual ask a marshal" 

....but now I'm curious to see the results.

 

[Adolf Hamster]

This seems overly complex for the result of "if it hurts more than usual ask a marshal" 

....but now I'm curious to see the results.

well it kinda started with me wondering what the effect of the magnus effect would have on range with different bb weights.

my current champion theory is there's a range of velocities that you'll get enough lift for a certain hop setting and because a heavier bb takes longer to slow down it'll stay getting lifted for longer hence the extra range.

mainly because for a long time i thought the lightest bb would get the most range (and as a result ran .2's but i wasn't factoring in how well the magnus effect worked at lifting the bb.

basically it was as much for my own understanding as anything else.

 

[CiderPunk]

surely 1.3 joules of energy transferred over the same surface area would feel the same regardless of the weight/speed? this calls for practical experimentation!

 

[gasman]

Are you volunteering as test candidate.?

 

[Nick G]

I wouldn't object to sites limiting ammo weights for snipers

 

[Rogerborg]

plus a refresher in the ol' excel is always handy.

Uh, there's a column missing.  You need an extra one where a BB with the same fps, mass and backspin knows that it should go 15m further because of the Tokyo Marui magic dust.

 

[Adolf Hamster]

Uh, there's a column missing.  You need an extra one where a BB with the same fps, mass and backspin knows that it should go 15m further because of the Tokyo Marui magic dust.

oh that's easy, just go into the "0.2g" sheet and change Cd from 0.47 to 0.3 to compensate for the magic dust's effect on wake formation.

 

[Nick G]

Lets also hope they know about joule creep

This got me thinking. I've just chrono'd my L96 (known as Binky) to see where it is at. 499 fps on '20s  then tested .43s and was 350 fps or 2.43 joules. So pretty much bang on the legal limit . No two ways about it that is going to sting even well beyond our MED of 30 meters.