Gel block calibration BB gun

[MilGunsmith]

We currently use a BB gun to calibrate gel blocks for bullet lethality testing. We are looking to replace the Daisy 880 pump gun with something more durable. We can fabricate anything and cost is no object for parts. This could be fired from a fixed mount to ensure repeat location hits, and triggered manually or electrically. We can use a large Nitrogen tank and regulator for pressure. What parts are recommended for a valve and breach assembly? We have two .177"cal BB barrels already. Any drawings or plans for something already in use?

[Moonbogg]

I'd buy a high-end PCP airgun and swap the barrel with a smooth one for BBs and just use that. You can connect the gun to a large air tank.

[jackssmirkingrevenge]

I'd buy a high-end PCP airgun and swap the barrel with a smooth one for BBs

Honestly that sounds like a sensible solution, and it doesn't even need to be a high end gun.

My understanding is that you need to fire a 0.177” steel BB into the gelatin at a velocity of 590 +/- 15 feet per second, I would go for something like the Beeman QB78D with perhaps a magnet somewhere around the breech to hold the BB, and a regulated nitrogen supply replacing the CO2 power. You can keep the standard hammer strength and tune to the right velocity by regulating the pressure. Remove the action from the stock and mount it on something sturdy et voila. You can even keep the rifled barrel, although technically as BBs are 4.4mm diameter a dedicated smoothbore BB barrel will be slightly more efficient.

Of course if you want something fancier there is a lot of room to play but if what you're doing is single shots from a fixed position at a fixed target and the most important parameter is consistent velocity, it doesn't need to be more complex than that.

[MilGunsmith]

We are trying to build this without having to purchase a complete airgun, as the purchasing department wont allow that, but we can by parts. I have BB barrels in the shop and the nitrogen regulated setup. just need something in between . No stock needed, mount everything to a fixture. Lever or button to fire.

[jackssmirkingrevenge]

A quick exhaust valve like this one should do the trick.

In order to actuate it you could hook up something like this to your gas supply and the QEV pilot.

Something like that in principle: