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BBMG detent alternative

This area is for the discussion of BB or airsoft sub machine guns, and or other small arms such as pellets.
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Unread postAuthor: POLAND_SPUD » Mon Aug 22, 2011 1:35 pm

bbmgpistonblockermod
I like it... at least there is some progress :wink:
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Unread postAuthor: warhead052 » Mon Aug 22, 2011 2:25 pm

It looks like it will work. I would use plastic before brass though to make sure it would work. If it works then I would use metal, but why waste 20-40ish dollars if it won't work?
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Unread postAuthor: saefroch » Mon Aug 22, 2011 6:19 pm

I'm still a fan of bbmgdetentblockerv2.png, it seems the most simple and easy to machine to me (hey, even I might be able to make it), so why the bbmgpistonblockermod.PNG?
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Unread postAuthor: jackssmirkingrevenge » Mon Aug 22, 2011 8:50 pm

warhead052 wrote:I would use plastic before brass though to make sure it would work. If it works then I would use metal, but why waste 20-40ish dollars if it won't work?


It doesn't actually cost that much, and most synthetic materials aren't cheap either. Teflon for example is more expensive that most metals.

I'm still a fan of bbmgdetentblockerv2.png


I'm kind of leaning towards it myself to be honest, although I still thing the first design also gas its merits, if nothing else it doesn't depend on the projectile for sealing.
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Unread postAuthor: warhead052 » Mon Aug 22, 2011 8:54 pm

jackssmirkingrevenge wrote:
warhead052 wrote:I would use plastic before brass though to make sure it would work. If it works then I would use metal, but why waste 20-40ish dollars if it won't work?


It doesn't actually cost that much, and most synthetic materials aren't cheap either. Teflon for example is more expensive that most metals.


Wow, I guess I should invest in a lathe then. I just need to get a job first. Is there any reason why teflon is more expensive? Or is it merely supply and demand?
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Unread postAuthor: jackssmirkingrevenge » Mon Aug 22, 2011 11:06 pm

warhead052 wrote:Is there any reason why teflon is more expensive? Or is it merely supply and demand?


I imagine the synthesis is quite costly, but there are much cheaper polymers like Delrin and UHMWPE that work just as well.
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Unread postAuthor: saefroch » Tue Aug 23, 2011 12:23 am

I'm guessing its the synthesis. F<sub>2</sub> and HF can't be that easy to get. A quick wikipedia skimming shows that Fluorine is rare because its nucleus is highly reactive in stars, combining often with He to form Ne, or with H to form O and He.

The problem I have with the first two designs is that they must first seal the bolt, pressurize, trigger, agitate, then feed. The design types with an actual detent need only pressurize, pop, agitate then feed. No blowing air out the barrel with nothing in it, waiting for another BB to feed.
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Unread postAuthor: jackssmirkingrevenge » Tue Aug 23, 2011 1:45 am

saefroch wrote:I'm guessing its the synthesis. F<sub>2</sub> and HF can't be that easy to get. A quick wikipedia skimming shows that Fluorine is rare because its nucleus is highly reactive in stars, combining often with He to form Ne, or with H to form O and He.


I'm guessing one of the precursors is hydrofluoric acid, which is extremely tricky to work with as it will dissolve pretty much anything, including glass, so requires special equipment and safety measures. I should know ;)

The problem I have with the first two designs is that they must first seal the bolt, pressurize, trigger, agitate, then feed. The design types with an actual detent need only pressurize, pop, agitate then feed. No blowing air out the barrel with nothing in it, waiting for another BB to feed.


With any design, until a BB makes its way to the breech, some air is going to be wasted. Even with the breech detent air is going to blow out before the BB seals the chamber.

With BBMGs, if air is flowing out of the barrel, generally so are BBs. The first two designs have the advantage of a much higher pressure difference between chamber and barrel when the firing cycle starts, so BBs are going to be sucked into the breech even quicker.

I'm thinking of making a small 1mm calibre of the first design, to see it improves performance in terms of penetration and reliability, as the sentry project is still on the shelf at the moment.
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Unread postAuthor: POLAND_SPUD » Tue Aug 23, 2011 5:32 am

I'm thinking of making a small 1mm calibre of the first design
lol you'll never learn... build a propa 6mm prototype for god sake...

1mm are much lighter than standard bbs and the performace will suck
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Unread postAuthor: jackssmirkingrevenge » Tue Aug 23, 2011 5:56 am

POLAND_SPUD wrote:1mm are much lighter than standard bbs and the performace will suck


I need a "sandblaster" in my armoury though, for summer cleaning with projectiles safe enough to be fired vertically.
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Unread postAuthor: saefroch » Wed Aug 24, 2011 12:17 pm

Didn't you say though that the 1mm BBs weren't all exactly the same size and shape? I see a potential sealing problem...

My point is that there is EXTRA air wasted (yes, there's already plenty wasted) with some of the designs you posted. Like comparing it to a cloud or simple detent, where all the airflow is used for either pressurizing behind the BB or loading, whereas your designs blow air in (particularly the first one) to pressurize the bolt, which is not loading or propelling anything.

EDIT: Would it even be prudent to try to synthesize PTFE from HF and some carbon chain? Wouldn't it be easier to just replace the Hs with Fs from F<sub>2</sub>?

And on another little note, has anyone ever tried or thought about feeding multiple detents with one vortex block? Feeding two 6mm detents would probably not require a block more than .6" in diameter, not much bigger than normal, right? One could even cut little channels into it to help the BBs feed to one side or the other, not the middle.
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Unread postAuthor: jackssmirkingrevenge » Wed Aug 24, 2011 11:43 pm

saefroch wrote:Didn't you say though that the 1mm BBs weren't all exactly the same size and shape? I see a potential sealing problem...


The first two designs operate independently of the projectile size and shape - as long as it fits in the barrel it's fine.

My point is that there is EXTRA air wasted (yes, there's already plenty wasted) with some of the designs you posted. Like comparing it to a cloud or simple detent, where all the airflow is used for either pressurizing behind the BB or loading, whereas your designs blow air in (particularly the first one) to pressurize the bolt, which is not loading or propelling anything.


Fair point, however in this case I'm not too concerned about being economical with airflow, rather optimising muzzle energy.

Looking at the global picture, note that eliminating the detent increases rate of fire, meaning a given target will require a shorter burst (in terms of firing time) to be destroyed, so you're still saving gas.

Would it even be prudent to try to synthesize PTFE from HF and some carbon chain? Wouldn't it be easier to just replace the Hs with Fs from F<sub>2</sub>?


Apparently not.

has anyone ever tried or thought about feeding multiple detents with one vortex block? Feeding two 6mm detents would probably not require a block more than .6" in diameter, not much bigger than normal, right? One could even cut little channels into it to help the BBs feed to one side or the other, not the middle.


You mean have a twin barrel BBMG with detents at the breech? Technically it could only fire both barrels at the same time, because if only one barrel is blocked air will flow out of the second barrel not allowing enough pressure to build up to fire the first.
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Unread postAuthor: saefroch » Thu Aug 25, 2011 9:43 am

jackssmirkingrevenge wrote:Fair point, however in this case I'm not too concerned about being economical with airflow, rather optimising muzzle energy.

Looking at the global picture, note that eliminating the detent increases rate of fire, meaning a given target will require a shorter burst (in terms of firing time) to be destroyed, so you're still saving gas.
I'm not entirely sure you'll save gas. I can certainly see how removing the detent increases rate of fire, but it seems you're losing muzzle energy per projectile and opting for a lot of ammo used more quickly, placing these designs for fire rate and muzzle energy between a detent and a vortex.

I guess another source of our disagreement here is that I have this idea of an airsoft BBMG that conserves air and has high muzzle energy, I didn't realize rate of fire was such an important consideration.

Thanks for the quick feedback. I don't pretend to know as much about chemistry and BBMGs as you do :P.
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Unread postAuthor: jackssmirkingrevenge » Thu Aug 25, 2011 11:32 am

saefroch wrote:I'm not entirely sure you'll save gas. I can certainly see how removing the detent increases rate of fire, but it seems you're losing muzzle energy per projectile and opting for a lot of ammo used more quickly, placing these designs for fire rate and muzzle energy between a detent and a vortex.

I guess another source of our disagreement here is that I have this idea of an airsoft BBMG that conserves air and has high muzzle energy, I didn't realize rate of fire was such an important consideration.


Ironically, when I first started out on spudtech I was appalled at how happy people were with their horribly inefficient clouds and vortexes, there are a lot of archived debates where I championed the quest for better efficiency, with higher muzzle energies at the expense of rate of fire. The whole auto piston and pop-off valve series was in response to this.

These days, I have the benefit of a SCUBA tank and two paintball tanks so I'm not longer limited to the feeble 110 psi my compressor puts out, plus with a high speed camera I can appreciate individual impacts even at high rate of fire so "braaaaap!" as opposed to "dakka dakka dakka" is not a problem.

Thanks for the quick feedback. I don't pretend to know as much about chemistry and BBMGs as you do :P.


I'm not a formally trained chemist, but I've worked in the industry for seven years now, you tend to pick up a lot ;)
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Unread postAuthor: saefroch » Thu Aug 25, 2011 3:26 pm

Don't mean to get off-topic, but how large is that SCUBA tank and what pressure do you keep it at? I think you mentioned you run 800psi on the outlet of the regulator?
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