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A Case for Using .12g BBs in Close Quarters

Many people transition to sidearms when getting into close quarters, since most guns nowadays shoot pretty hot. Now, other people bring up the fact that doing it for safety’s sake is a little weird since modern gas pistols actually shoot at least as hard as most electric rifles nowadays.

We all know that .12g BBs have lousy accuracy at range.  But let’s assume you’re expecting close-quarters fighting.  Would .12g BBs from the same gun hurt less than heavier ammo if you got hit?

I think it would, and here is why.

THE SHORT VERSION:  I think my test results make a pretty strong case supporting the idea of loading .12g BBs into a gun (like a sidearm) to lessen the risk of injury to others in close-quarters.

I shot BBs from the same guns at things and measured how hard the BB hit those things.  BBs from 0.12g to 0.43g were shot from a GBB, a NBB, and a Bolt-Action Spring rifle (which all have different ways of propelling a BB when fired.)

All tests showed the same results: the heavier the ammo, the harder the impact (more energy transferred.)    The lighter the ammo, the lighter the impact (less energy transferred.)

In all cases, .12g BBs very clearly transferred less energy (hit less hard) than any other ammo tested, when fired from the same gun.

So here is a quick recap. The question I posed myself (and you fellows) was “All other things being equal, would loading lighter ammo into the same gun cause less of an ouch?”

A practical application of this would be loading a gun (like a sidearm) with .12g BBs in order to make it more CQB-friendly. Could this be reasonably expected to help?

I discussed this recently on the forums at Airsoft Canada and it seems that some people think yes (heavier ammo = more energy = more ouch, so lighter ammo = less ouch), some people think no (lighter ammo = higher FPS = same energy in the end), and some people just like to argue.  😀

Well, nothing gets the brain working like a good experiment.

My hypothesis: Lighter ammo will overall transfer less energy, compared to heavier ammo from the same gun.

The test setup: Putty is used as a way to capture and visualize BB energy transferred. Shoot the putty from point-blank ranges with a variety of BB weights (.12g, .20g, .28g, .30g) from a variety of guns. Measure the results with a depth gauge, and eyeball the hole.

Why do it this way:
Three main reasons:

  • The putty deforms when hit, and “freezes” when no more energy is spent deforming it. This is easy to measure and seems to be a consistent measure of energy transferred. As a side note, energy transfer should be optimal since the BB stays in full contact with the putty until it is no longer penetrating (energy transfer being a function of how long something can stay in contact over how much area, and all that. No glancing shots, etc.)
  • It therefore doesn’t matter that putty doesn’t act like skin, or that skin in different spots feels pain differently. We’re interested only in relative energy between different weight BBs from the same gun. As long as it’s consistently measured, we’re good.
  • Shooting things that do something when you shoot them is fun.

Assumptions, Out Of Scope, etc:

  • In all individual tests: Same gun, same propellant, same putty, same range.
  • We are not measuring quantative energy, just relative energy between different weight BBs from the same gun. So converting “size of dent” into “joules” or whatever isn’t in scope.
  • The bigger/deeper the hole in putty, the harder the hit.
  • The harder the hit, the bigger the OUCH potential.
  • Only point-blank ranges are tested. Results valid at point-blank will be valid at longer ranges since it’s impossible for a BB to go faster the further it goes.
  • In other words, if a .12g BB doesn’t hit as hard as .20g at point-blank, it never will no matter what range you go out to.
  • How well energy is retained at longer ranges for different weights is out of scope. (Meaning whether .20g retains energy better at longer ranges than .12g is out of scope.)


This is a typical target:

First up is a KJW 1911 Gas Blowback on duster at point-blank range (2m). NOTE THAT THE WHITE SPOTS INSIDE THE HOLES ARE PAPER FRAGMENTS. BBs DID NOT PENETRATE.

Observations: There is a clear progression in penetration depth related to BB weight.

Next is the same KJW 1911 Gas Blowback, but this time with a CO2 magazine.

Observations: The relation of penetration to BB weight is still clear. Overall all BBs penetrated further. The CO2 mag was observed to shoot noticeably harder.

Next up is a KJW MK1 Non-blowback on duster.
The non-blowback should fire the BB with a fixed “gas charge” unlike a GBB which keeps the gas on as long as the BB is in the barrel. This surely has some kind of effect on BB fps, but that’s not specifically of interest here — does a NBB versus a GBB change the trend we’re observing?

Observations: Same progression observed — more BB mass means more observed putty penetration.

Finally we have an APS2 bolt-action spring rifle.

Test 1 Observations: All BBs except for .12g penetrated into the backstop. Clearly .12g had less energy, but what about the rest?

Another test was done, this time with BDU material in front of the putty instead of a paper target.

Observations: Same trend observed as all previous tests. Heavier weight from same gun = more penetration.

Two decimal places of measurement for a depth gauge into putty smacks of “measure with micrometer, mark with chalk, cut with axe.” This is not lost on me. So I did a quick test where I shot the putty with 4 rounds of .20g and measured each. The measurements were remarkably consistent; biggest deviation was .12mm. Admittedly it’s a small sample size (just like the rest of this experiment) but it looks like putty is not only consistent but the depth gauge is as well. At least, enough to see what I’m trying to see.


  • Heavier BBs (i.e. more mass) fired from the same gun equals more energy transfer on impact. (Compared to lighter ammo)
  • Lighter BBs (i.e. less mass) fired from the same gun equals less energy transfer on impact. (Compared to heavier ammo)
  • The different mechanics of operation between a NBB versus a GBB versus a spring piston doesn’t change this.
  • Shooting stuff is pretty fun.

Therefore, while pain is subjective and depends on where and how one is shot, I think it would be reasonable to explore loading .12g BBs into a gun for the purposes of making it more appropriate for CQB – for example into a gas gun sidearm which otherwise might shoot pretty hot. (And CQB is an environment where the poor accuracy of .12g at range won’t be much of an issue.)

Whether it actually makes enough of a practical difference to make a hot gun safer? Maybe!


It was pointed out to me in discussion that many puttys are non-Newtonian (i.e. their resistance to deforming depends on how they are hit).  I decided to do some follow-up tests where I shot something that deformed uniformly and showed visible damage that could be measured.  Floral arrangement foam was the answer.

I stretched BDU fabric over the foam and repeated some of the tests.  I wanted to see if I got the same results.

A few changes made:

  1. Fired at 6″ away instead of 2m (six inches is more “point blank” if we’re talking about Airsoft)
  2. Foam has BDU material over it.
  3. Still used 0.12g, 0.20g, 0.28g and 0.43g BBs. But this time only from the 1911 GBB on Duster and an APS2 bolt-action.

Short story: Same results trend observed (the heavier the ammo, the harder the impact and deeper the penetration when fired from the same gun.)

It was interesting! Some lessons learned:

– Have a vacuum handy. It’s messy.
– Vacuum also helps suck out the debris from the holes so you can see better.
– Not nearly as easy to measure this stuff with a depth gauge since it’s so frangible/light/fragile. I gave up trying and just had to eyeball it.
– Shooting stuff is fun.

1911 on Duster from 6″ away

Clear progression of wider/deeper/messier impact the heavier the BB gets. The BDU material is noticeably “dirtier” with foam-bits as the BBs get heavier.

APS2 from 6″ away

Same observations as before (heavier BBs hit harder), but more pronounced.

Finally I used the fishing line to cut up the APS2 result foam to bisect each impact crater so you can see how deep and wide they are from a better angle!

Neat (and odd) that the difference between .12g and .20g is bigger than the difference between .20g and .28g, even though they are both .08g apart from one another.

You don’t see it so much from this angle, but the width increase of the crater I think is more noticeable as you go .20 -> .28 -> .43 but the increased depth of penetration is harder to see.

Those are my tests.  They clinch it for me — a 0.12g BB transfers much less energy (hits less hard) than heavier ammo from the same gun.

Whether .12g BBs in a “hot” gun makes it safe enough to use in close-quarters isn’t an answer I can give. But it’s clear that .12g BBs carry less energy when fired from the same gun.