4,2 mm pipe for 4.5 ammo

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bravootome
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Tue Jan 05, 2021 11:34 am

is a 4,2 mm brass pipe ( inside diam) good for 4,5 lead pellets?
how accurate will it be as there are no grooves ? does it worth to try ?
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farcticox1
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Wed Jan 06, 2021 5:35 am

That sounds tight. I used some stainless pipe from Mcmaster https://www.mcmaster.com/tubing/metal-t ... /id~0-183/ at 150psi I still had to slightly open the loading end of the tube to pre-compress the skirt a bit. Dome head pellets seem to be most accurate. viewtopic.php?f=29&t=26858
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bravootome
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Wed Jan 06, 2021 10:38 am

farcticox1 wrote:
Wed Jan 06, 2021 5:35 am
That sounds tight. I used some stainless pipe from Mcmaster https://www.mcmaster.com/tubing/metal-t ... /id~0-183/ at 150psi I still had to slightly open the loading end of the tube to pre-compress the skirt a bit. Dome head pellets seem to be most accurate. viewtopic.php?f=29&t=26858
no mcmaster @ here, only few pipes for modelism, iam lookink for a 5.5 mm pipe for years, it is more rare than diamonds ( if i had to choose, i would take pipe )
i took a look at you accuracy tests , not good for 9 m, may be for 30 m... so ill let it go...
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mrfoo
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Wed Jan 06, 2021 12:13 pm

How about using a reamer? in brass you could probably ream from 4.2 to 4.5 without steps, or pick up an adjustable reamer and use that.
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farcticox1
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Wed Jan 06, 2021 5:19 pm

I guess an old rifled barrel would be the answer, but I think that's kind of cheating :?
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mrfoo
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Thu Jan 07, 2021 3:57 am

farcticox1 wrote:
Wed Jan 06, 2021 5:19 pm
I guess an old rifled barrel would be the answer, but I think that's kind of cheating :?
Rifling buttons are cheap on aliexpress. Just saying, like.
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bravootome
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Thu Jan 07, 2021 10:31 am

i was thinking ( not sure i can find my words, but....) to squeeze the part where the bb seats in the barrel , about 5 cm, from outside -in ( like fx barrels )
let me explain why : the bb sets down into the barrel so when it is blasted with air it may go any where , it needs to be caught in the middle to fly straight and follow that patch . for that it's the hopup , it make it roll backward , but wth the power of an airgun the hopup will not work..
got some experience with aluminium 6 mm barrels for modelism , the bb had friction with the barrel, accuracy was better than now.
so i will use a drill head, drift pin, mandrel (?) to squeeze it in 3 lines in equal manner , just a little bit so the bb will stay there , this way it will not be affected by the dust or the angle you hold the gun
ive observed that when a dust particle seats in the same spot inside the barre,l the bbs hits also the same spot, till the dust is gone, than another dust in another place on the paper, and so on for few years ...........
so, what do you think ? is my theory good ?
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mrfoo
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Thu Jan 07, 2021 1:00 pm

Totally stupid idea, maybe, for use of bbs...

What if you were to bend the barrel down slightly, right at the start by the breech? Would that perhaps force a consistent contact between bb and the top of the barrel, effectively guarantee a hopup effect even with the extra speed you're generating? A bent barrel to get straight shots :)
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bravootome
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Thu Jan 07, 2021 2:01 pm

mrfoo wrote:
Thu Jan 07, 2021 1:00 pm
Totally stupid idea, maybe, for use of bbs...

What if you were to bend the barrel down slightly, right at the start by the breech? Would that perhaps force a consistent contact between bb and the top of the barrel, effectively guarantee a hopup effect even with the extra speed you're generating? A bent barrel to get straight shots :)
i did not expressed correctly perhaps .............
the bb will have contact in 3 segmented linear points, not up or down, its not a " like hopup" sistem. the bb will not have a hopup effect,

ive been looking at this effect for years, just think about it, but the "bents" must be extremly perfect so this to happens .
this 3 lock system is used in most of mechanics system just to prevent other things to go crazy
i will test it with the risk of fk up a 40 euro barre( and it will not be the first) l , ill post the resuls...
and i bet no one made this mod before.
just hope the drill head is able to press the barrel ....
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mrfoo
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Thu Jan 07, 2021 3:58 pm

No, I understood that, I was suggesting a possible other approach.

Crimping should work, as you suggest, use a mandrel of the desired size inside to avoid going too small. You can put a significant amount of pressure on with a drill chuck, but if it doesn't work you might look into finding someone who has a lathe. I can't think of any easily-made mechanism for doing this off the top of my head, but a few relatively complex ones spring to mind :)
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bravootome
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Sat Jan 09, 2021 9:07 am

i ve not "tuned " the barrel as it looks like inaccuracy still comes from the dust, but the dust goes in from the brand new pcp hand pump, witch is exactly what i got it for - to have no dust. it is vaseline mixted with water . as the pump is a brand new china made, it has no filter, and there is no place from to buy one around here. my idea is to un mount the pump, remove all the vaseline and add silicon oil ....
or to move to another country where airguns are accepted ...
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jackssmirkingrevenge
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Wed Jan 13, 2021 6:19 am

mrfoo wrote:
Thu Jan 07, 2021 3:57 am
Rifling buttons are cheap on aliexpress. Just saying, like.
damn, I never thought to look

I wonder if it would prompt a visit from the powers that be as it goes through customs...

The same has been happening locally with so-called "fuel filters" that have become widely available.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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mrfoo
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Wed Jan 13, 2021 6:37 am

Hah, fuel filter.

Ironically, an off the shelf oil filter, intended to be used as such, might well do a better job. For example,



27dB is 512 times quieter.
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Wed Jan 13, 2021 6:53 am

mrfoo wrote:
Wed Jan 13, 2021 6:37 am
Ironically, an off the shelf oil filter, intended to be used as such, might well do a better job.
They have some good effect because of their sheer volume, same as a 2 liter soda bottle, but are definitely impractical compared to a proper series of well designed baffles.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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bravootome
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Fri Jan 15, 2021 8:14 am

jackssmirkingrevenge wrote:
Wed Jan 13, 2021 6:19 am


I wonder if it would prompt a visit from the powers that be as it goes through customs...

what do you mean ?
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