Air Rifle discharged sparks

[Mike Carter]

Hello All,
I want to know if anyone has ever observed this.
We were doing a "black out" drill where my athletes were checking NPA consistency in low light aiming a black paper. 10m
Anschutz 8001 air rifle and Champions Choice green tin pellets.
One of the shots created sparks out the muzzle.
I've never seen this before, nor my head coach or other shooters.
Maybe it's common and the low light conditions made it visible.
Has anyone else witnessed this?
I suspect cheap pellets with a trace of carbon from the smelter embedded in it.
Interested to hear comments.

Regards,
Mike

[Andre]

If anything, I would think carbon would act as a lubricant for the pellet. Isn't graphite infused wax used to coat pellets?

I have heard of fireballs shot from air rifles when filling them with pure oxygen, but never sparks. Look down your bore to make sure no metal particles have scratched the bore.

[dronning]

Could it have been a static discharge?

- Dave

[JamesH]

I've heard of airguns 'dieseling', oil left in the bore vapourises and ignites.

Would carbon particles produce sparks? I'm not sure. What would cause them to ignite in the first place?
Rust particles might or might not also.

[mikeyj]

The discharge from a PCP rifle is pretty cold, so I doubt anything was ignited. I suspect you were seeing small particles of something illuminated by the lighting.

[Gerard]

During my first month with a Baikal 46m I saw sparks a couple of times, when shooting from a darker hallway into a lighted room with lighted target. I asked about it here, and was told by 'experts' (know-it-alls) that it didn't and couldn't happen. So I was hallucinating, apparently. But teasing aside, yeah, somehow I was seeing sparks. Very fine, a spray of about 10 to 12 tiny pale yellow sparks, going up and to the right. It was rather disconcerting. But as the pistol shot in this stopped. So I assumed it was some sort of ignition from the factory oil. Which is very weird in an SSP. But oh well, weird stuff happens sometimes. Similarly I've been instructed that one can not possibly see the pellet in flight from a 10m AP, but I see it often, depending on lighting.

[JamesH]

I guess it could be droplets of oil, or dust.

If you're seeing them in one direction only its likely they're particles catching a shaft of light.

Strange things can happen with static electricity also.

[Rover]

Obviously, none of you guys have bitten a Wintergreen Lifesaver in a dark room.

[divingin]

Obviously, none of you guys have bitten a Wintergreen Lifesaver in a dark room.

I think that's a piezo-electric reaction, (as I recall) something to do with how the sugars fracture.

As to the airgun, I'd suspect dieseling if the particles are actually emitting light.

jky

[Gerard]

Except that dieseling is only likely with a spring-piston type. There's nothing suddenly compressing the air/oil with an SSP such as the 46m. Nor with the Anschutz, which is a PCP. One needs rapid compression for dieseling. These airguns have only rapid expansion.

[mikeyj]

Obviously, none of you guys have bitten a Wintergreen Lifesaver in a dark room.

I think that's a piezo-electric reaction, (as I recall) something to do with how the sugars fracture.

As to the airgun, I'd suspect dieseling if the particles are actually emitting light.

jky

Triboelectric, not piezoelectric. And PCP guns don't diesel. They can't, as there's no compression and hence no heating as there is in spring guns. In fact, it's the opposite. The temperature of the air released in a PCP is colder than ambient, as it's expanding.

[robf]

Yep, seen it before. In fact been sent a video of it happening as well. Can only assume it's tiny particles getting hot as the lead travels down the barrel. Seen it on two different PCP rifles running at about 800fps

[Rover]

I wouldn't have believed it, but yesterday I saw it (once) while shooting my Walther LPM1 SSP.

I have no explanation for the phenomenon.

[kevinweiho]

My theory is the fire piston effect. I know what's happening is air expansion and not compression, but if you think about it for a moment, a pellet at the breech and a minute amount of oil in the barrel or valve, the release of air only takes milliseconds, it could be possible.

[mikeyj]

My theory is the fire piston effect. I know what's happening is air expansion and not compression, but if you think about it for a moment, a pellet at the breech and a minute amount of oil in the barrel or valve, the release of air only takes milliseconds, it could be possible.

P

When the gun is cocked, the air in the compression chamber is compressed and heated, but quickly cools owing to the mass of conductive metal. When the gun is fired, the expanding air cools rapidly, so by the time it teaches the muzzle it's significantly colder than the surrounding air. Whatever people are seeing, it's not combustion. SSP and PCP guns don't experience the heating found in spring guns.

[kevinweiho]

SSP and PCP guns don't experience the heating found in spring guns.

There is no heat produced in ssp’s or pcp’s compared to a springer but if you were to use pure O2, you know what will happen. What I was trying to convey is that ssp’s or pcp's may act like a fire piston and can produce combustion by rapid and adiabatic compression when oil or lint are present in the valve or barrel.

[mikeyj]

SSP and PCP guns don't experience the heating found in spring guns.

There is no heat produced in ssp’s or pcp’s compared to a springer but if you were to use pure O2, you know what will happen. What I was trying to convey is that ssp’s or pcp's may act like a fire piston and can produce combustion by rapid and adiabatic compression when oil or lint are present in the valve or barrel.

Except you don't get rapid adiabatic compression in a PCP or SSP as you do in a spring gun. Springers are legendary for burning anything combustible in the barrel or compression chamber, but as you note, there's just no heat source in a PCP or SSP.

I've had many PCP and SSP guns, and I've never seen this phenomenon. Reports of it aren't accompanied by reports of smoke or the odor of burning, which you get in spring guns, so I strongly doubt it's lubricant burning. That leaves the pellet, and a lubricated lead pellet in a match barrel isn't going to shed burning particles.

One poster here notes particles moving up, and to the right. If it was combustion, it should be symmetrical. But if it was a spray of lube caught in a light, you'd expect it to be asymmetrical, only appearing where it reflected the light back to you.