A place for general potato gun questions and discussions.
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Gun Freak
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Thu Apr 15, 2010 8:12 pm
When sleeving the thin walled 1.5" with sch80 2", is there too much friction to have a sort of bolt-action mechanism for a breech load? Any examples? Thanks... I got a good idea....
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Marffy
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Thu Apr 15, 2010 9:04 pm
I don't know but it all depends on if the 1.5" pipe just slides in the 2" or not. If You have to use more force then one finger can handle to push the pipe into the other pipe,then i wouldn't make a breech loader. there is always the simple magazines you can make which are just T fittings with another barrel sticking out to put the ammo in. hope I helped...
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Hubb
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Thu Apr 15, 2010 9:07 pm
Generally, sleeving these two pipes will make more friction than is comfortable for a breech loader.
What type of launcher are you planning on? The thinwall pipe may not even need to be sleeved.
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jor2daje
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Thu Apr 15, 2010 9:22 pm
I used sch80 for a breach cover on my golfball gun, I just sanded down the area a tiny bit the buffed it so everything slid smoothly.

Patience is a virtue, get it if you can, seldom in a women, never in a man.
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clemsonguy1125
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Thu Apr 15, 2010 9:36 pm
Hubb wrote:Generally, sleeving these two pipes will make more friction than is comfortable for a breech loader.
What type of launcher are you planning on? The thinwall pipe may not even need to be sleeved.
He told me it was a compact piston valve, I never sleeved my 5 foot gb barrel on my piston valve
That is all.
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Gun Freak
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Fri Apr 16, 2010 7:20 am
Ok well are thin walled 1.5" golf ball barrels usually strong enough without a sleeve? I wanted the barrel support to be connected to the sleeve and the ajustable hop-up at the end and the GB barrel sliding inside the 2 inch for a breech load.
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Hubb
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Fri Apr 16, 2010 7:23 am
The thinwall pipe is rated to 200 psi. A lot of people forget this and think the thinwall pipe is not as rigid as it really is. For safety sake, I would sleeve the pipe if you plan on going over 120psi, but otherwise, I've never found it absolutely necessary.
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mark.f
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Fri Apr 16, 2010 8:37 am
The problem isn't the pressure rating.
The problem is that when fired, the thinwall pipe flexes a lot more than regular 1.5" SCH-40, and this flexing can cause the barrel to fail.
When supported properly (by sleeving or rigid barrel supports every few feet), the pipe can be used without worry. The sleeving material doesn't even need to be pressure rated, but rigid enough to support the SDR-21.
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Gun Freak
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Fri Apr 16, 2010 11:30 am
I am mainly fiting around 100 psi but definitely not above 105. Will unstall a pop-off too. I Mainly wanted to sleeve it for durability and straightness when fired, but also to be able to breech load the golf balls. The end will be crowned and have a muzzle break and adjustable hop-up. Remember Hubb... it's a BARREL not a chamber.
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Hubb
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Fri Apr 16, 2010 12:48 pm
Gun Freak wrote:Remember Hubb... it's a BARREL not a chamber.
And is probably something I know a bit more about
As you may be familiar, the higher the pressure goes up, the harder the barrel will jar (recoil) when fired. As was mentioned, this jarring is what causes the damage to a thin barrel and not the actual pressure. I've taken a launcher up to 120 psi with this same type of barrel (unsleeved, 5 feet long) and had no problems as long as it was braced against the chamber.
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Gun Freak
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Fri Apr 16, 2010 3:22 pm
Ok thanks for your help Hubb. I will probably make a breech int eh 2" sleeve, when I can finally get around to making my GB cannon...
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Marffy
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Fri Apr 16, 2010 5:19 pm
Hubb wrote:The thinwall pipe is rated to 200 psi. A lot of people forget this and think the thinwall pipe is not as rigid as it really is. For safety sake, I would sleeve the pipe if you plan on going over 120psi, but otherwise, I've never found it absolutely necessary.
Yes, if you go above 120psi i would definitely sleeve it. i had my 1inch thin wall barrel blow up in my face. little to tight of a fit on the ammo and BOOM! luckily it snapped instead of shattered and i was un-harmed. but i still use un-sleeved thin-wall still (but the way its set up it shouldn't snap/blow up), i'll learn my lesson one day.
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Gun Freak
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Fri Apr 16, 2010 5:25 pm
Ok well I'll just use an unsleeved thin walled 1.5" barrel and I'll make the breech from sch80 2".
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mikespahn
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Wed Apr 21, 2010 9:09 am
how much pressure is lost in a breech like the one pictured? i was thinking of a few ways to make one air tight but if the loss is not so much, i won't even worry about it.
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jor2daje
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Wed Apr 21, 2010 9:29 am
I dont think the loss is to big, if I were to but more effort into it Im sure something with o-rings or neoprene gaskets could be figured out. But I dont think even my friction breach loses much pressure I couldnt tell any difference from before the breach and after.
Patience is a virtue, get it if you can, seldom in a women, never in a man.