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Posted: Sun Feb 12, 2012 7:38 pm
by POLAND_SPUD
You mean metal-on-metal?
well actually I meant delrin-on-metal but now that you mentioned metal on metal :-D

Posted: Mon Feb 13, 2012 12:35 am
by jackssmirkingrevenge
I don't think metal on metal would work reliably unless it was for very high pressures. Delrin on metal would certainly solve a lot of design headaches, my only trial so far (aside from this fill rig) was when I converted the cheap-oh QEV to full auto and that wasn't exactly airtight, but I made no attempt at making sure the inner faces were true.

Posted: Mon Feb 13, 2012 5:31 am
by CpTn_lAw
You could try to sabot a .177" pellet or BB in a .22" sabot. That's what i've done for the 757 m/s 0.24g airsoft BB. it was powered by a ridiculously large chamber (in comparison with the caliber) and a 1 meter long 8mm barrel.

I'm so dissapointed ultimatespudgun don't ship in france, i'm desperately searching for a reliable ignition module.

Great setup there JSR btw :D

Posted: Mon Feb 13, 2012 5:45 am
by Crna Legija
CpTn_lAw wrote:I'm so dissapointed ultimatespudgun don't ship in france, i'm desperately searching for a reliable ignition module.
Have you asked them? they shipped to jsr and his cave ain't all the far from France don't see why they wouldn't.

Posted: Mon Feb 13, 2012 6:13 am
by CpTn_lAw
I went all the way up to "shipping methods" and "no shippment options are available to selected country"

Posted: Mon Feb 13, 2012 7:14 am
by jackssmirkingrevenge
CpTn_lAw wrote:You could try to sabot a .177" pellet or BB in a .22" sabot. That's what i've done for the 757 m/s 0.24g airsoft BB. it was powered by a ridiculously large chamber (in comparison with the caliber) and a 1 meter long 8mm barrel.
Even at supersonic speeds, a little 0.177" BB isn't carrying much energy anyway so I prefer to go straight to 0.22", I will be happy with 25-30 ft/lbs for cartridges.
I'm so dissapointed ultimatespudgun don't ship in france, i'm desperately searching for a reliable ignition module.
Jagerbond and USGF are both very reasonable fellows, I'm sure that you could sort something out.
they shipped to jsr and his cave
Apparently more difficult than North Korea :D

Posted: Mon Jul 02, 2012 3:32 pm
by jackssmirkingrevenge
Been experimenting with this, with some disappointing results for 0.22" pellets. Historically the issue was that either that the o-ring couldn't hold the pellet at pre-ignition pressures, or it held it too tightly and never released the projectile.

I managed to "tune" a cartridge to release the projectile at 8 bar, anything above would leak, and tested it at various mix numbers. At 9x, the maximum mix possible, it would still not release the projectile. What happens with the pellets seems to be that unlike a spherical projectile, it has two major diameters, the head and the end of the skirt. This means that even if the head makes it through, the skirt then gets caught in the detent and boo, *fizzle*.