Mitcho's BB Rifle idea

[al-xg]

With the 6mm barrel on my copper QEV launcher GGDT says they go supersonic but i always thought that just using air at normal temperatures wouldn't alow the projectiels to go so fast (but maybe because of dead volume ?)

.12g BB just disapear when fired at 200psi and don't hit the target... They only go where they are aimed at when 3or more are sort at a time.

[jackssmirkingrevenge]

With the 6mm barrel on my copper QEV launcher GGDT says they go supersonic but i always thought that just using air at normal temperatures wouldn't alow the projectiels to go so fast (but maybe because of dead volume ?)

have a look here

[potatoflinger]

A lot of high-end bb guns can go supersonic, one from Cabelas can go up to 1,600 fps, so it is possible that you could go supersonic, but it would decelerate really fast, not to mention you would have to use insane pressure.

[al-xg]

yay! im supersonic then !!!! wooohh
Ill be getting the parts for semi auto before next week so i might pick up the 6mm barrel again.

[potatoflinger]

yay! im supersonic then !!!! wooohh
Ill be getting the parts for semi auto before next week so i might pick up the 6mm barrel again.

Just because some guns can go supersonic doesn't mean that yours will, it just means that it is possible.

[al-xg]

yes of course but there's more chance that GGDT is right though, so its just as supersonic (in theory) as Mitchza89s.
Id like to try in though a chronograph one day.

[jackssmirkingrevenge]

A lot of high-end bb guns can go supersonic, one from Cabelas can go up to 1,600 fps, so it is possible that you could go supersonic.

if you're referring to the Gamo, that doesn't count as an example because it's a spring piston rifle, since the air is compressed suddenly its temperature rises, also you have to consider the diesel effect of piston lubricant detonating in the chamber, which has been proved (by comparing airguns fired in a vacuum to those fired in a normal atmosphere) to be a significant contributor to spring airgun performance.

yay! im supersonic then !!!! wooohh

GGDT is a good performance guide but it cannot be depended on for accurate velocity data, you can only gauge this with a chronograph - they're not that expensive, you can get a cheap one off e-bay for very little, or even make your own using two photo-diodes and a PC microphone cable, there's a very good how-to on jimmy's site.

[Mitchza89]

Hey guys, this is a total noob question but I really don't have much of an idea... Where could I get a barrel thats good idea for bb's? I heard that some people use break line or fuel line or something and some others use copper. I live in Australia so where abouts and what would be the best stuff to use for as cheap as possible?

[wannabie]

well im my hybrid im going to be using a 1/4" x 6" brass all threaded nipple that fits 8mm bb's almost perfectly i get my bb's from a camping store and they sell them as sling shot rounds

[Mitchza89]

Ahh that could work pretty well. So you buy BB's from any camping shop? I didn't know that :S Is that in Australia though?

[wannabie]

yep im in Aus yeah most camping shops if they sell sling shots they will sell them there steel or chrome i think

[Mitchza89]

Thats awesome. With the length of the 1/4in brass, I wish that came in 1m lengths haha.

[wannabie]

yeah well you can only wish although i have seen on some american sites they have it upto 2 feet long !!! lucky americans ... good luck on your bb gun

[CpTn_lAw]

I've looked at wht you plan on making, it sounds great! i had approx. the same thing. You won't get 2600 fps...i pumped mine at 300 psi, and "only" got 1300 fps.
I suggest you use 0.36 grams BB's, 8mm OD copper is perfect fit for airsoft BB's. 15mm galvanized steel is great for a chamber => holds a lot of pressure.

[Mitchza89]

Thanks alot. Yeah I thought 2600fps was waaaaaay too optomistic hahaha. 1300fps is def. nothing to sneeze at though. thats pretty damn quick.... What was the penetrating power on your bb gun you made? I'm thinking it was pretty decent with 1300fps behind the little bugger