BBMG detent alternative

Building or modifying BB, Airsoft, and Pellet type of guns. Show off your custom designs, find tips and other discussion. Target practice only!
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POLAND_SPUD
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Sat Dec 10, 2011 11:01 am

hmm so it seems you need something MOAR reliable than a cloud

why not a simple T + this interupter (or a small air cylinder... yeah, I think you should machine a small T that has a tiny inbuilt air cylinder)
Last edited by POLAND_SPUD on Sat Dec 10, 2011 11:32 am, edited 1 time in total.
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Sat Dec 10, 2011 11:12 am

I'm actually with you on this one, poland :D
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Sat Dec 10, 2011 12:31 pm

Something like what s0ka did here?

[youtube][/youtube]

Breech that locks when the chamber is pressurised, and starts to reload as the round is fired?

Alternatively, it could be the other way round.

The trick is timing the delay to give time for the projectile to leave the barrel before the breech is unlocked.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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POLAND_SPUD
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Sat Dec 10, 2011 2:05 pm

Something like what s0ka did here?
nope that looks like a typical 3 way + QEV + air cylinder combo... Even if he used a bV or a hammer valve as the piloting valve


I meant a detent bbmg with a simple T (+interupter or whatever you want to call it)
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al-xg
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Sat Dec 10, 2011 2:38 pm

Breech that locks when the chamber is pressurised, and starts to reload as the round is fired?
His breach is in the barrel, the breach opens inbetween shots.


If you're after efficiency, you really need to ditch the agitated BB design, even with a 100% efficient valve, the air wasted in trying to chamber the next BB ruins it.



How about you use your Ebay parts to make a simplified-updated version of this ;)

I have started a larger calibre semi-auto version.
It shoots ~14mm (.55cal) epoxy rifled bullets. (or anything that size...)
It runs with a 3/4" QEV so the ram isn't embeded, it is just part of the chamber.
Damn, nearly 5 years later... what have I been doing :)
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Sat Dec 10, 2011 3:01 pm

POLAND_SPUD wrote:I meant a detent bbmg with a simple T (+interupter or whatever you want to call it)
peectures?
How about you use your Ebay parts to make a simplified-updated version of this
That thread was exactly what got the chamber pressure activated reloading mechanism into my head, and what I mean by this:
Breech that locks when the chamber is pressurised, and starts to reload as the round is fired?
As you said:
The bolt only moves back once the pressure in the chamber has dropped enough
Effectively how s0ka's design operates too.
If you're after efficiency, you really need to ditch the agitated BB design
I still want a hopper though, only way to get a large volume of ammunition really.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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al-xg
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Sat Dec 10, 2011 3:52 pm

The bolt only moves back once the pressure in the chamber has dropped enough
Effectively how s0ka's design operates too.
Yes but in most cases, unless you have a massive spring on the air ram, a tiny diameter piston or a stupidly long barrel, even the tiniest amount of pressure will keep it locked and the projectile will have cleared the barrel.
The projectile is likely in the barrel for ~5ms or so unless he is shooting at 12000rpm that shouldn't be a problem.
I still want a hopper though
Electric Hi-cap airsoft magazine ?
Or just a mechanically agitated hopper like paintball ones ? (that seems to be a bit optimistic, seems more like 1500rpm)
Surely 1500rpm would be enough right ?


I'd stay that would probably still be more energy efficient and provide more shots fill.

I guess you could use a small air turbine to drive the feed !
Back to the old topics again... :D
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POLAND_SPUD
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Sat Dec 10, 2011 9:18 pm

peectures?
here is my draweeng:
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Sat Dec 10, 2011 10:13 pm

al-xg wrote:I guess you could use a small air turbine to drive the feed !
Back to the old topics again... :D
:D

An unpowered feed would probably work just as well ;)

Image
here is my draweeng
I see it working with a spring behind the BBs and pulsed airflow, but otherwise...

Maybe something like the attached, fed with a hopper?
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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POLAND_SPUD
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Sat Dec 10, 2011 10:19 pm

I see it working with a spring behind the BBs and pulsed airflow, but otherwise
lol it has an aircylinder so it's great (lol you do realize that's an air cylinder right ? I didn't include tubing in that diagram)

Plus the vertical port is there just to act as a chamber - it's fed air through the mag
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Sat Dec 10, 2011 10:32 pm

POLAND_SPUD wrote:lol it has an aircylinder so it's great (lol you do realize that's an air cylinder right ? I didn't include tubing in that diagram)

Plus the vertical port is there just to act as a chamber - it's fed air through the mag
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POLAND_SPUD
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Sat Dec 10, 2011 10:42 pm

yeah, exactly... it should work quite well as far reliability is concerned
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Sun Dec 11, 2011 2:08 am

I think thats actually actually a very feasible idea... I might have to try this one, i wish I could pump out concepts like you do :roll:
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al-xg
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Sun Dec 11, 2011 5:12 am

An unpowered feed would probably work just as well
Well a conventional hopper certainly doesn't work at any decent sustained ROF without a considerable amount of shaking, and well the advertised max speed is 11 BPS. (that video was showing 25BPS)

Smaller heavier projectiles probably would work alot better, but if they're anything like paintball ones will require some sort of shaking about for sustained fire.

But mechanical could be very cool, imagine using one of these
[youtube][/youtube]
as a hopper and have them roll down a wire guide to the BBMG, it'd ba like a pneumatic one of these:
[youtube][/youtube]



You could nearly do with a light detent just before the air ram, to prevent air leakage between shots.

You also want some sort of wedge shape on the air ram, or an oval chamber port to prevent the next BB from rolling directly above the air ram.
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Sun Dec 11, 2011 7:45 am

The more I fiddle with these, the more it makes me want to get cartridges to work :)

This idea has been in my head for a long time...
hectmarr wrote:You have to make many weapons, because this field is long and short life
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