How to Chronograph a shotgun

[Miseryguts]

Hi, trying to develop a load for a new aquisition  (Winchester 1901 lever action 10G shotgun) that will not break my already arthritic shoulders. Lots of stuff on the net from our american cousins about using the cheapo Prochrono series to ascertain MV, but when I try it with my old chrono, the velocities are a tad optimistic to say the least - 4300fps for one, and 3800 fps for the other.

Tried the chrono nearer/further away, to no avail. I do not think it is the wad upsetting it - surely that would give low speeds not high speeds?

Could the shock wave be triggering the first receptor just as the shot mass reaches the second?

Am loth to put the unit a long way off in case the unit gets shot, even if I have had it years and it owes me nothing!

Everybody  says the Labradar will not work on SG (that's what I normally use for my rifles and pistols) - or is that an urban myth?

M scratchin' 'is 'ead in Monmouthshire

[Rewulf]

Never done it , but if I did , I would rig up some kind of aperture , so you only get one pellet going through the chrono.

You may need to make 2 so if you get a deflection off the first aperture,  it doesn't destroy the chrono!

Then just take some averages, the fact you're using SG , makes the whole operation easier.

[One on top of two]

Find someone with a magneatospeed V3 .

job done ✔️ 
 

oh and the labradar will work on shotgun , but slugs only .

[Akeld]

I've seen it done with the chrony type chrono's, basically the chrony was placed behind railway sleepers with the rods sticking up proud of the barricade, can't comment on the accuracy of it. The more shots the better the average i suppose

[BlueBoy69]

You can use Doppler radar to track and give velocities of multiple projectiles, rockets, missiles, etc., as I used to do it all the time with sabotted, other types of ammunition and missiles that spat our or projected more than one thing. The control software and I presume internal hardware of the Labradar is unfortunately simply not set up for this sort of thing though.

If asked to instrument trials using shotguns, I'd have used smaller skyscreens or a light boxes, some example hardware in the links below.

http://www.prototypa.com/ls-01l-intelligent-light-gates-1

https://msinstruments.co.uk/pdf/858-opticaldetector.pdf

http://www.ballisticmeasurements.com/precision-light-screen.php

https://oehler-research.com/system-89/

https://sydortechnologies.com/ballistic-impact-testing/velocity-measurement/

For canister shot from far larger guns, bigger and very robust (and blooming heavy) skyscreens would be used, but only with ample angled steel plate protection over each set of three skyscreens. For note, NATO-certified testing requires six skyscreens, two pairs of three, all observing the same point in space. So from front to rear, skyscreens 1, 2, 3, 4, 5 & 6, with screen 1 paired with 6, 2 with 5, and 3 with 4. The screens would be levelled in X, Y and Z axes, and all would be surveyed in using a theodolite and related to the gun's trunnions and muzzle. No valid testing could be done with one pair of screens or sensors, though we might use one on its own, or a single pair to trigger certain photographic or radiographic systems.

Anyway enough waffle about what I used to do... try this, he (Paul Harrell) seems to be getting OK observed velocities (OVs) with his testing of shotguns with a basic (one channel, shudder) chronograph system.