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Mk IV QEV Popoff. Updated 22 Feb

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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Unread postAuthor: rna_duelers » Wed Apr 15, 2009 6:40 am

Now that's a nice guna!I've always been a fan of semi auto,I tried a design similar to this back in the day(Thread somewere) but never got anything as good as this.The ROF as the end of that 2nd clip is nice reminds me of a woodpecker gun used in the pacific in WWII do you ever plan on upping the calibre of this?Also how much did you pay for that QEV?As I can source one of the same design in 1/2" for around $50 I'm just wondering on price to compare.


I wish we had airsoft aswell,Then I might actually like small calibre as I would have readily available ammo for once as it's a [female doggy] trying to scavenge all the ball bearings and odd sinkers you find.
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Unread postAuthor: psycix » Wed Apr 15, 2009 6:43 am

Ooh neat T-piece!
I still haven't figured out what to do with mine.

How reliable does it feed?

Oh and fix that barrel fit...
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Unread postAuthor: SubsonicSpud » Wed Apr 15, 2009 7:14 am

rna_duelers wrote:Now that's a nice guna!I've always been a fan of semi auto,I tried a design similar to this back in the day(Thread somewere) but never got anything as good as this.The ROF as the end of that 2nd clip is nice reminds me of a woodpecker gun used in the pacific in WWII do you ever plan on upping the calibre of this?Also how much did you pay for that QEV?As I can source one of the same design in 1/2" for around $50 I'm just wondering on price to compare.


I wish we had airsoft aswell,Then I might actually like small calibre as I would have readily available ammo for once as it's a [female doggy] trying to scavenge all the ball bearings and odd sinkers you find.


The QEV i use was from a aussie company called Bellpro http://www.bellpro.net They are pretty cheap, a 1/2 QEV from them is about AUD$36.

Yeah I would like to make a larger calibre but the air usage starts to get out of hand. If I was going to make a large calibre I would probably go for JSR's design popoff valve to try and reduce air usage, plus a blow forward bolt would be on the cards as well.

Kmart seems to be pretty good value for small fishing sinkers a pack of 150 No.2 size is about AUD$4.50
I also just ordered 400 7mm beads off ebay for like AUD$4 :P


psycix wrote:Ooh neat T-piece!
I still haven't figured out what to do with mine.

How reliable does it feed?

Oh and fix that barrel fit...


Psycix, Thanks, it seems to feed pretty well, probably get about one double feed per 28round mag but it depends a lot on ROF. If you fire at a low ROF it seems to get a few more double feeds, but the rubber stop I have planed should stop that. I think most of these mags have a sort of "sweet spot" when it comes to ROF, it is just a matter of tuning the gun to match :?

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Unread postAuthor: jackssmirkingrevenge » Wed Apr 15, 2009 7:42 am

I think most of these mags have a sort of "sweet spot" when it comes to ROF, it is just a matter of tuning the gun to match


I find that adding short length of tube full of lead in the magazine after the ammunition helps with reliable feeding, a sort of "gravity powered spring"

psycix wrote:Ooh neat T-piece!
I still haven't figured out what to do with mine.


How about an inline magazine like SPG proposed here?

Basically just a barrel extension running rearwards from the T-piece, with the air from your valve coming up the T instead so that it enters between the first two BBs?

Nice and easy to do, no worries about double feeds as the air would push the remaining BBs out the way, and that way you don't have anything sticking up out of the gun to snag/get in the way of sighting.


The only problem I can see is the BBs in the mag coming back with such force after the air pressure is down that they might skip the detent, hence adjustability is a good idea.

It would look something like this:
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Unread postAuthor: POLAND_SPUD » Wed Apr 15, 2009 8:50 am

did anyone test a T with larger ammo...? like marbles ?? or with a hopper??

I tried testing it but it end up in breaking several marbles and sending shattered glass at my face (I wasn't aware that something went wrong... but somehow I was expecting that something would go wrong...
and before you ask I didn't use eye protection - but I am fine)

I suppose that was due to a jam (or it casued a jam)... well anyway... I don't feel like doing it again for a while... so any imput is appreciated
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Unread postAuthor: psycix » Wed Apr 15, 2009 10:18 am

jackssmirkingrevenge wrote:
psycix wrote:Ooh neat T-piece!
I still haven't figured out what to do with mine.


How about an inline magazine like SPG proposed here?

Neahhh I'm not feeling much for it. Makes your gun very long, thus taking up barrel length.
I think I'll skip the BB blowforwardbolt for now and build one for marbles... :twisted:
BTW, I fired bb's using a T-piece, vid is up!
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Unread postAuthor: Technician1002 » Wed Apr 15, 2009 10:18 am

jackssmirkingrevenge wrote:
I think most of these mags have a sort of "sweet spot" when it comes to ROF, it is just a matter of tuning the gun to match


I find that adding short length of tube full of lead in the magazine after the ammunition helps with reliable feeding, a sort of "gravity powered spring"

psycix wrote:Ooh neat T-piece!
I still haven't figured out what to do with mine.


How about an inline magazine like SPG proposed here?

Basically just a barrel extension running rearwards from the T-piece, with the air from your valve coming up the T instead so that it enters between the first two BBs?

Nice and easy to do, no worries about double feeds as the air would push the remaining BBs out the way, and that way you don't have anything sticking up out of the gun to snag/get in the way of sighting.


The only problem I can see is the BBs in the mag coming back with such force after the air pressure is down that they might skip the detent, hence adjustability is a good idea.

It would look something like this:


The graphic is close to what the model battle ship guys use, but for the resistance, they use an o ring. Sorry no photos, but a description is here.
http://www.repairfaq.org/filipg/RC/F_Ship_Kombat.html#SHIPKOMBAT_018
These events are fun to attend and yes they really do shoot each other full of holes until they sink. Loads of fun and eye protection is required.
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Unread postAuthor: SubsonicSpud » Wed Apr 15, 2009 4:58 pm

POLAND_SPUD wrote:did anyone test a T with larger ammo...? like marbles ?? or with a hopper??

I tried testing it but it end up in breaking several marbles and sending shattered glass at my face (I wasn't aware that something went wrong... but somehow I was expecting that something would go wrong...
and before you ask I didn't use eye protection - but I am fine)

I suppose that was due to a jam (or it casued a jam)... well anyway... I don't feel like doing it again for a while... so any imput is appreciated


Marbles will probably be a lot more difficult to feed didn't their brittleness, you would probably need to spring load the mag to stop them jumping around and impacting each other. The Tee would probably need to be made of plastic or something softer than steel to also reduce the chance of breakage.
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Unread postAuthor: psycix » Wed Apr 15, 2009 6:48 pm

Marbles are large enough to go blowforward bolt.
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Unread postAuthor: SubsonicSpud » Wed Apr 15, 2009 9:24 pm

psycix wrote:Marbles are large enough to go blowforward bolt.


Agree with you on that one, would be a lot more reliable.

By the way, I just bought another 900 rounds :twisted: so i will get plenty of damage pics today. Also found some brass tube at the hobby store that is a perfect fit for my ammo :P
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Unread postAuthor: jackssmirkingrevenge » Thu Apr 16, 2009 1:52 am

psycix wrote:Makes your gun very long, thus taking up barrel length.


You could loop it back through 180 degrees and have it along the barrel.

SubsonicSpud wrote:By the way, I just bought another 900 rounds so i will get plenty of damage pics today. Also found some brass tube at the hobby store that is a perfect fit for my ammo


Damage videos please, close up ;)
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Unread postAuthor: SubsonicSpud » Thu Apr 16, 2009 3:57 am

jackssmirkingrevenge wrote: Damage videos please, close up ;)


WATERMELON :twisted:

[youtube]http://www.youtube.com/watch?v=AD0cNxNg6zc[/youtube]



The front

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and the back

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Unread postAuthor: jackssmirkingrevenge » Thu Apr 16, 2009 5:56 am

fan-friggin-tastic!!!

That's very healthy penetration, brilliant :D is this with the tighter barrel?
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Unread postAuthor: SubsonicSpud » Thu Apr 16, 2009 6:32 am

jackssmirkingrevenge wrote:fan-friggin-tastic!!!

That's very healthy penetration, brilliant :D is this with the tighter barrel?


Yeah I know :D I was not really expecting full penetration, even the couple of double feeds ripped through it :twisted:

Yes it is the new barrel, I have not shot it through the crony yet, but I will be interested to see the results. I'm actually going to reduce the chamber volume by half, as there is a lot of air wastage, and it is way too loud. Tomorrow I might crank up the pop off as high as it will go and see if I can penetrate some plywood too :P

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Unread postAuthor: MountainousDew » Thu Apr 16, 2009 12:07 pm

SubsonicSpud wrote:Tomorrow I might crank up the pop off as high as it will go and see if I can penetrate some plywood too :P

SubsonicSpud


Yayyy, plywood pentration, maybe.... I can't wait!
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