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.20caliber pellets in a 5mm barrel?

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.20caliber pellets in a 5mm barrel?

Unread postAuthor: john bunsenburner » Mon Feb 02, 2009 10:25 am

Well after searching around for about 5hours and writing 6 e-mails to just as many comapnies in switzerland i found that gettign a 4.5mm tube for .177 pellets is close to impossible. Though i considered a brake line i want my gun to look realistic and so have a very large wall thickness for the barrel. I looked around for other common pellet diameters and found a .20 pellet is exactly 5.08mm wide, my question is:

Would a 5.08pellet fit into a 5mm barrel with some pressure providing a very tight fit or would it be close to impossible to make it go in. Please consider i am making a bolt action gun and so the air pressure its self would have to push the pellet into the barrel(hmm, i wonder if this could be used like a burst disk in a combustion...), so if you can give me an aproximated amound of pressure i would need to squeeze the pellet down the barrel.

If you think the pellet would not go into the barrel it would be great if you could suggest an alternative(if there are now alternatives then i can always go look for a brake line, or get some snadingpape ad make all the pellets a bit smaller).

Thank you.
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Unread postAuthor: jackssmirkingrevenge » Mon Feb 02, 2009 10:41 am

It should fit nicely in a 5mm barrel. There are some manufacturers like JSB that offer different grades, for example 4.50, 4.51 and 4.52mm pellets, you might want to check that out to get an exact fit.
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Unread postAuthor: john bunsenburner » Mon Feb 02, 2009 11:07 am

i prefer to just buy pellets locally but thanks any way. As my question is pretty much answered i have a few little questions about GGDT(as D hall is not responding to my pm):

1. what is the hammer distance?

2. When i have a hand operated hammer valve what should i put as hammer mass and hammer force?
3.And what is the initial position of the projectile in other words: when the projectile starts of at the very back of the barrel can i put 0?
4.I am trying to use the gun optimizer but what ever i do i get a run time error 11(division by zero) what am i doing wrong?

oh and thank you for you quick response jsr
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Unread postAuthor: psycix » Mon Feb 02, 2009 11:40 am

From:
http://www.thehalls-in-bfe.com/GGDT/Click usage and then "main input window"
Valve -> Hamr Dist
(Not shown in screen shot) This value represents the distance traveled by the hammer/striker in a hammer valve.


2- The mass of your hand. The energy calculated by E=1/2mv^2
3- Yes, usually this is 0, but if you have a bolt loader or something and dont want to calcualte dead space, you can just enter a number here. The space that comes up will add up to your dead space.
4-Cant help you with this one.
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Unread postAuthor: Gippeto » Mon Feb 02, 2009 2:48 pm

A small point to note here;

The major difference between a blowgun and a hammer valve is the hammer.

If you do not intend to have a hammer, then you have a blowgun, not a hammer valve.

Problems with getting an error on ggdt are easiest diagnosed by you providing a screen shot showing the error.

In this manner, the values which you have entered for the various fields can be seen, evaluated, and a solution to your problem found.
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Unread postAuthor: john bunsenburner » Mon Feb 02, 2009 2:59 pm

I solved my GGDT problems(error11 miraculously disapeared after retyping all my things). I understand where you are going Gippeto but arent we being a little bit too picky, and seeign as how my hammer/blowgun valve is about 25cm long and 3ck wide with the ID of the inside tube(stem?) being 8mm i doubt you can call it a blowgun. Also it is all inline and works just like a hammer accuted valve but with my hand instead i doubt it can be called ablow gun. Oh and last but not least a blow gun involves having the air turn about 90° from its normal imput, my valve is strait and all inline. But that all doesnt really matter in the long run. Thank you for all your help.
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Unread postAuthor: Gippeto » Mon Feb 02, 2009 3:01 pm

I see that you are firm in your resoltion to not listen.

Do as you will.
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Unread postAuthor: john bunsenburner » Mon Feb 02, 2009 3:09 pm

I am far from being firm i just dont see how my valve is a blowgun or a hammer valve for that matter... I built it like the explosive air realease valve. I belive you that the valve is a blow gun valve but not a blow gun...

If you do not intend to have a hammer, then you have a blowgun, not a hammer valve.


If you say its a blowgun i will belive you though seeing as your explaination makes sense to the most part. Though the looks are far from a blowgun i do agree to you, to an extent that is.
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