Just reviewed a long discussion thread on the dangers of accidental dieseling damaging the seals in a break barrel. I'm a retired mechanical engineer and understand the technical issues involved. I wouldn't expect the metal parts on even a low power airgun to fail when induced dieseling using grease or oil behind a pellet might only double the power of a shot at most. The increased sharp pressure pulse of the small detonation might cause a distortion of internal parts on a poorly designed break barrel airgun with minimal overload margins. But it's not like having a system overload failure on an airgun with a full tank of CO2 or HPA air behind it.
The posts about dieseling induced failures specifically cited the piston seals. By the looks of the few pictures of damaged and blackened seals I've seen, they failed due to partial melting and eventual embrittlement from the heat of hydrocarbon detonations combined with the increased pressure of the pulse. Makes sense since vendors probably don't select seal material with the expectation that the seals would need to hold up to the heat and increased pressure of regular or induced dieseling for power increase. Nonetheless, some models of break barrel airguns probably already use a very tough seal material which can in fact hold up very well to much increased heat and pressure. This is the kind of thing which a general airgun repair shop tech who has worked on many different manufacturers' airguns might know about. All I can do it to experiment with my own airguns until something I do breaks them. And then I have collected one data point, plus a wealth of experience by trying to repair it on my own.
I am wondering if anyone who works on springers and gas piston rifles have noticed any models which look like they would hold up under intentional dieseling for power increases.
Out of curiosity I recently chronied a couple dozen 18g diablo pellets out of a .22 break barrel pellet rifle. Then I filled the skirts to the top with Vaseline and chronied another dozen pellets. The average velocity increase went from 580f/s to 773f/s (13.6fpe to 24fpe), a power increase of ~75% per shot. The velocity per shot varied between about 750 and 800f/s (50fps) with the Vaseline, and between 566 and 596f/s (30fps) without. The gun still shots at the original power level after a couple of dry pellets cleared out a bit of residue from the dozen Vaseline loaded pellets just shot through it.
A power increase up to 20fpe out of a low power <12fpe break barrel isn't a big deal here in the US where we don't have any 12fpe power limits. But it might be a very big deal to hunter with a 12fpe springer who might consider adding a dab of Vaseline to a pellet while loading it in order to have a 20fpe hunting shot.
When we used to talk about using Helium to increase power output of PCPs by 60+% on the old Yellow forum 30 years ago I would rarely ever see public comments about it from the 12fpe airgun folks in the UK. They noticed all right but didn't want to raise a lot of local attention about it. If I lived in a 12fpe area I wouldn't mind knowing which break barrel rifles had seals which would be likely to hold up to the occasional double-power diesel shot for hunting purposes. Or else where to get replacement piston seals with increased heat and pressure resistance.
The posts about dieseling induced failures specifically cited the piston seals. By the looks of the few pictures of damaged and blackened seals I've seen, they failed due to partial melting and eventual embrittlement from the heat of hydrocarbon detonations combined with the increased pressure of the pulse. Makes sense since vendors probably don't select seal material with the expectation that the seals would need to hold up to the heat and increased pressure of regular or induced dieseling for power increase. Nonetheless, some models of break barrel airguns probably already use a very tough seal material which can in fact hold up very well to much increased heat and pressure. This is the kind of thing which a general airgun repair shop tech who has worked on many different manufacturers' airguns might know about. All I can do it to experiment with my own airguns until something I do breaks them. And then I have collected one data point, plus a wealth of experience by trying to repair it on my own.
I am wondering if anyone who works on springers and gas piston rifles have noticed any models which look like they would hold up under intentional dieseling for power increases.
Out of curiosity I recently chronied a couple dozen 18g diablo pellets out of a .22 break barrel pellet rifle. Then I filled the skirts to the top with Vaseline and chronied another dozen pellets. The average velocity increase went from 580f/s to 773f/s (13.6fpe to 24fpe), a power increase of ~75% per shot. The velocity per shot varied between about 750 and 800f/s (50fps) with the Vaseline, and between 566 and 596f/s (30fps) without. The gun still shots at the original power level after a couple of dry pellets cleared out a bit of residue from the dozen Vaseline loaded pellets just shot through it.
A power increase up to 20fpe out of a low power <12fpe break barrel isn't a big deal here in the US where we don't have any 12fpe power limits. But it might be a very big deal to hunter with a 12fpe springer who might consider adding a dab of Vaseline to a pellet while loading it in order to have a 20fpe hunting shot.
When we used to talk about using Helium to increase power output of PCPs by 60+% on the old Yellow forum 30 years ago I would rarely ever see public comments about it from the 12fpe airgun folks in the UK. They noticed all right but didn't want to raise a lot of local attention about it. If I lived in a 12fpe area I wouldn't mind knowing which break barrel rifles had seals which would be likely to hold up to the occasional double-power diesel shot for hunting purposes. Or else where to get replacement piston seals with increased heat and pressure resistance.
