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GBBR HPA Conversion


hustie12

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Hey guys,

 

I'm thinking about converting a GBBR to take HPA but ALSO have the ability to change magazines quickly, in a manner that the sun project and older 'classics' were able to.

 

So basically, the idea is to have an HPA hose permanently attached to the GBBR, so that the magazines hold only BB's. Judging by the available GBBR's on the market, this means I'll have to design and construct custom magazines.

 

Has anybody seen this done before?

 

I've never even seen a GBBR in person, does anybody know which type and brand would be most suitable for such a conversion?

 

I have a very well equipped machine shop at my disposal. Constructing complicated parts shouldn't be a problem.

 

Lastly, here's an example of something I'm going for, but notice they have the hose attached to the magazine:

 

http://www.youtube.com/watch?v=CxjRemWTStA

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@ LordElpus: No, the HPA would be permanently connected to the rifle. The magazine would hold only BB's, not air.

 

Regarding the Daytonagun conversion, that's something I'll look into, albeit not to purchase but to steal ideas from. I'd much rather make a project of this than purchase a drop in kit.

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you would have to get the air supply to the magwell and that would not be possible without having an external hose/pipe. how that person has done itin the video is pretty much the only way it's going to work with a GiM GBBR.

 

 

If you want a HPA gun with the hose attached to the rear of the gun then Daytonagun is pretty much your only option.

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P* = PolarStar = HPA powered gearbox replacement that is reminiscent of the old "classic" rifles. Most any AEG M4 will accept it, and you can keep on using your normal AEG mags.

 

DTG = DaytonaGun AR kit = HPA powered internal kit. I want to say they go in G&P WOC receivers, but don't quote me on that.

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Conversion would be as simple as drilling and tapping the fill nozzle for a QD fitting.

 

The threads of GBBr's fill valve is usually ~ m5x.8, so a 10-32 thread will usually be an easy fit.

 

Honestly though, the tapping of a GBBr for HPA is pretty impractical unless you are going for a SAW/LMG loadout. Tapping and modifying an AK platform for an externally fed drum magazine would be a bit more practical and include machine work to satisfy your desire for a more hands on project.

 

If you want to head in the direction of machine work and customization, pick up an Escort, Daytona Gun or Shoei replica. Once you get an understanding of the engine, you can use the general operating principles and adapt it into something like this...

 

0L9yN.jpg

 

The engine can be boiled down to 5 tubes and and bolt timing.

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So basically, the idea is to have an HPA hose permanently attached to the GBBR, so that the magazines hold only BB's. Judging by the available GBBR's on the market, this means I'll have to design and construct custom magazines.

 

Gas-in-magazine GBBRs are complex and filled with bits that you don't need or want in a remote-line rig, and they're expensive bits too. Ideally you would base your project on a gun that already takes AEG magazines.

 

What's a P*? [...] And the reason I don't want to "just get something" is because I want to BUILD something, hence the reason I posted this in the project section.

 

A Polar* is a solenoid-controlled HPA unit that replaces the V2 gearbox found in AR15-pattern AEGs. Of interest to you are the fact that it takes AEG magazines, fits into AEG receivers, takes HPA out of the box, and is probably the best system for outright performance. On the downside, the system doesn't feature blowback or simulated recoil, two of the high points of GBBRs (though since you've never seen a GBBR, you don't know what you're missing). In terms of 'doing a project' the fitting isn't supposed to be very difficult and the precision design of the Polar* means you won't be machining your own any time soon.

 

One answer to your question is a DaytonaGun-style conversion of an AEG. These are essentially just remote-powered GBBRs, with the realistic internal design giving you recoil and blowback, but while still using AEG magazines. These are relatively simple in design but quite complex to make, set up and work out properly; with no prior experience this would be a very involved project and potentially extremely dangerous if done wrong. This is probably the best solution, but the consequences of getting it wrong are certainly the worst.

 

For a first try, I'd be tempted instead to configure an ordinary GBBR to take HPA by machining an adapter that sat inside the magwell, giving you the necessary room for the HPA fitting and allowing you to use AEG magazines. You would have to move the hole in the magazine that accommodates the magazine catch to compensate, but there's no reason that AEG magazines couldn't be made to work in this fashion. Once the system was running correctly you could machine shortened magazines to fit the well properly. This is a rather inelegant solution but it requires very few custom parts and you're not fiddling with the internal workings of the gun; ideal for a first-timer.

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I like that last idea PureSilver. I'd rather not go with the PolarStar option because I want blowback. Also, I forgot to mention, whatever I end up with, it'd have to have a mechanism that would lock back the bolt on an empty magazine.

 

The DaytonaGun route seems promising, and almost exactly the sort of thing that I'm going for.. If I went for that I'd almost certainly investigate designing some sort of bolt catch mechanism.

 

Something else that caught my eye are the G&P "Challenge Kits" :

 

http://www.redwolfairsoft.com/redwolf/airsoft/Accessories_GBB_Other_WA_M4_Parts_G_P_WA_Assemble_Parts_Full_Set_for_Air_Toy_Model_Only.htm

 

http://www.evike.com/product_info.php?products_id=35717

 

According to Evike and Redwolf, those kits are based on the WA/Tanio Koba designs. Out of curiosity, does anybody know how the size of AEG magazines compares to the WA magazines? It'd be good to know this to determine if it's feasible to convert AEG magazines for WA system use.

 

Just to keep things straight,the list of features for the final design is:

1.) Powered by an external air source

2.) Easily changed magazines (Do not have to connect external air to magazine each time the magazine is changed)

3.) Bolt locks back on empty magazine

4.) Bolt will blowback while shooting (so not polarstar)

 

That's pretty much all I have so far. The list will probably grow.

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just like with pistol mags, GBBR GiM nozzle push a BB out from feed lips rather then the nozzle blocking the entrance to the hopup like in AEG systems so you will need some kind of conversion plate inside to mimic the AEG style hopup feed tube and the GBBR mag feed lips or you will need to try and adapt systema style mags.

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As an owner of the Daytonagun M4 engine powered gun, I can help you out anyway you like. There are few modifications on the gun, mostly on the upper receiver, that have to be made. Not to forget, the lower receiver has to be modified mainly in the magwell so the AEG mags fit in.

 

On the bolt catch, I recently asked about it and I was told "No bolt lock anytime soon". I guess theres still some questions how to connect the WA style bolt catch to the AEG magazines BB follower reliably. So bolt lock is still in the process of making.

 

The recoil is solid and after working out the gimmicks, its working rather well right now. Still some problems with magazines which results in unstable shooting performance due to airshaft chopping BBs because they arent pushed up fast enough(G&P magazines...).

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I've been bogged down with school work the past few weeks, hence no activity on my part. I'm still torn between the daytonagun or conventional GBBR route. It does seem like the daytonagun system is closer to what the final gun will function like though, it would just require a bolt lock added in. Is there any place I can view schematics for the daytonagun design?

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