Currency
You are here: REDWOLF > Home

Bite The Bullet

How hard do shotguns actually hit? (2009-08-20)

In this Bite The Bullet article, we will attempt to put a figure or at least a more accurate guideline fps range for a shotgun shot's fps by comparing the values with muzzle velocity from known guns.

Test idea:
All muzzle velocity measurements will be given in feet per second (fps) via the Guarder chrono using KSC .20g ammo.
Using the home-made ballistic gel made in a consistency to measure regular airsoft gun shots, the guns with known fps values will be shot into the gel yielding a penetration measurement that is found by using a vernier caliper which, in turn can then be compared with the penetration of the shotgun shots.
Since it fires a much lower amount of rounds per shot compared to the moscart, the problem with the higher powered shots making contact with the previous, lower powered shots in the gel will not be present or at least it would present a much lower chance of occurring.
Control:
With that in mind, a few guns with different power ranges must be used to provide a range of penetration distances to act as a control. All the shots will be fired into the same gel block to ensure the viscosity is constant throughout the test. The following guns have been chosen for the purpose of this test:
- A low powered springer pistol
- A NBB Ruger using 134a and on green gas
- a stock TM M4 AEG

Test: Knowing a shot from the shotguns will be sharing the energy provided from the same charge of gas or the spring, a lower limit control shot must be produced. This is where the low powered springer pistol is useful, with the NBB Ruger yielding 280fps and the springer pistol at 180fps, we now have the upper and lower control figures to work with. This would be necessary in the comparison between the upper and lower limit of the shotgun shots if it occurs.

Having proceeded with the upper and lower limit control shots, the measurement shots can then be taken with the other guns. This is to help determine the power of the moscart shots by narrowing down the error margin when comparing the penetration distance.

Every gun was chrono'd to give an idea of the correlation between the penetration distance and the fps figure. The shotguns are then fired on a fresh part of the gel block to ensure it will not interfere with an existing penetration path within the gel block.

After all the control shots and shotguns were fired into the gel block, the block was cut as shown in the pictures avoiding every penetration path made by the BBs so that the penetrated distance was not interfered. When measuring the penetration distance, an incision was made in front of the BB to allow the round to fall out, where it will leave a cavity clearly seen shortly after the round exits the gel allowing the measurement to be made with more precision.

Note: the Tanaka trench gun was tested on 134a gas and the Airsoft Surgeon slug-shot was using Co2 at 600psi

Results and summary:

Gun FPS reading Penetration (mm)
Springer pistol
175
32.18

TM M4 AEG

257

47.20

NBB Ruger (134a)

283

51.48

NBB Ruger (green gas)

415

81.62

TM M3

N/A

48.38 - 54.12

Tanaka Trench Gun

N/A

45.14 - 79.10

Airsoft Surgeon M870

N/A

54.74

With the results at hand, the penetration distance can be compared to the control shots with a known FPS value. Where the TM M3 have a similar penetration to the NBB Ruger on 134a, it can be said that the TM M3 has a muzzle velocity of 28010fps taking the slight penetration varience into account.

The trench gun however, has a much bigger upper and lower limit varience, the lower limit is a little lower than the TM M4 AEG at 257fps so the estimated fps of the lower limit shot would be 250fps. The upper limit however, is a whooping 79.10mm where it is only a few fps lower than the NBB Ruger on green gas. With these figures shown, it can be concluded that the Tanaka trench gun is capable of firing an upper limit of around 410fps. Giving it similar characteristics to a moscart shot where the BBs towards the front of the shell will be dramatically weaker than the ones towards the back of the shot, allowing the gas to accelerate the round more towards its target.