My completed AR2078 and the start of a new QB build!

[Jeffl]

Hello all, I thought I would post a picture of my completed ar2078, looks pretty well stock, its what's inside that counts in this one. I am shocked at just how accurate it is at 50 yards. I never would have guessed it possible. I have no chrony so I can only say it shots hard and is very consistent, although every 10-12last shots I get a flier that separates the nice tight group by 2-3the inches. I have no idea where to even start. I am running a jds air reg at 1400the psi. The rest of it are just the basic mods that you have all compiled here for us newbies to get a really food handle on our airguns. Simply put, I love it, I love it. I love it! It is so nice being able to shoot with out that ear cracking split of a high velocity 22 LR. Even the sub sonic 22's sound like a bomb going off compared to my ar2078. I am going to try and post photos.
I have cut the basic shape for the new stock I am building from a qb 78gun I bought from Eric at scopes and ammo. This qb is for a friend but I will use it as a template for my new stock build. I am a millwright by trade but my wood working skills to this point have been making "custom pens" for friends and crating up machinery to ship. I have cut the basic shape out although I can't decide what to do where the back of the gun ends and where the rear stock shape should start. I am open for suggestions. I am not sure how one even goes about carving the shape for your hand fit etc. A dremel and some files should get me going. The would iObama am using is padauk. I had nice piece lying around. I have enough for a second one if I ruin my first attempt and its got a lot nicer figuring. The wood is almost orange, coming up with a stain that will look good may be a little tricky. Trial by fire for this project. I would love to hear any ideas or you can just plain point out that I am doing something stupid if that's the case. I am going to order some 4130 tube so I can enlarge the reservoir size and fill to 3000 psi. I have no idea where one can get one of these "inline air regulators" they are using on the other guns. I would rather not have to make one. So many questions and I have hardly started. I will now try and post pics.

[Fastair]

If you have some nice paduak I would not stain it just oil it and it should look great

[rsterne]

I don't know what power level you are after, but if you use an inline regulator, make sure you install it with some volume between the regulator and the valve or you may be disappointed in the results.... About 1 cc per FPE is optimum, although you can get away with half that if you bump the regulator pressure up about 100 psi....

Bob

[Jeffl]

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This is all I got when I tried to upload photos! Please help!

[Jeffl]

I guess it sort of worked. I will post better photos as I figure things out. For the moment I am just happy I got it to work!

[Fastair]

That is going to make a nice looking stock. You are off to a good start.

[Jeffl]

About those inline air regulators.... who sells them? Can anybody recomend a source. I will looking at a 3000psi fill regulated on one the opposite side to 1000psi, maybe 1200psi. I have want this airgun below the 500 fps limit so I have more options as to where I can shoot. Online metals seems like a great source for the 4130blanks chromoly tubing and the pricing seems resonable. I have yet to see an inline reg set up for sale anywhere, unless you pick a gun that used one and order it as a replacement part. I feel like I am missing something here. Is this just not a popular way of doing things? My thinking was to have it attached to the gun in front of the valve and then be able use pr-filled tubes that you could swap out pf the airgun. The more I think about the less will remain of the original qb78 when complete. I suppose finding a source for inline regs, seeing exactly what they are all about and start making decisions once I am better informed. Thanks, jeff

[rsterne]

Most of the aftermarket inline regulators seem to be made in Europe.... The exception is the one that MAY be the easiest to adapt to a QB78, and that is the one sold for the Benjamin Discovery by Airguns of Airizona.... I believe that is a Steve Woodward design.... It is adjustable for output pressure and fits in the main tube, just in front of the valve.... Since it has very little plenum volume (between the regulator and the valve) it is best for reduced power levels, which is perfect for your application.... I have no idea what would be necessary to fit it into a QB tube, but the ID of the tubes is very close, and it you use a 4130/4140 tube of 7/8" OD x 0.065" wall (suitable for 3000 psi) it should just slide right in.... You would normally use a full length tube (as long as the barrel), which would give you a volume of about 7 CI.... Since you only want 500 fps, you can use a very low operating pressure.... I was able to get 500 fps in a Benjamin Disco running only about 500 psi.... That would give you (3000-500) = 2500 psi of useable pressure which is 2500/14.5 = 172 bar, which would give you 172 x 7 = about 1200 CI of air at 1 bar.... Since you should easily be able to achieve an efficiency of 1.0 FPE/CI (and likely much higher), and since 500 fps with a 14 gr. pellet is 7.8 FPE, you should be able to get 1200 / 7.8 = over 150 shots per fill.... Trying to make the main reservoir detachable while filled would be a lot more difficult than simply using a QD fittng on the front to fill it....

In order to run such a low pressure, you will need to reduce the hammer strike by fitting a lighter spring, cutting coils off it, or fitting a velocity adjuster.... Running too much hammer strike won't increase the velocity much (providing you choose the correct regulator pressure).... but it will waste a lot of air, drastically reducing shot count....

Bob

[AirGunEric]

The problem with those Woodward regulators is the price- $120.00 (would be a bit more for Canada)- this is why I have never had Steve send me any.

[rsterne]

Well the European ones are just as expensive (or more).... and I am not aware of any made small enough to fit the (under) 3/4" ID tubes on a Disco or QB.... Unless you make your own, I know of no other solution to regulate a QB internally.... I'm pretty sure you would need to drill a hole similar to the Disco gauge port hole in a QB tube to install it.... I believe it adjusts and vent through that hole.... Here is another solution for a Disco that could be adopted for a QB.... all you need to do is find someone to make it for you....





Of course you would have to base it on a QB valve instead of a Disco valve.... I used a Ninja piston because they are readily available.... but you still have to make the two piece housing which becomes a new valve front end.... Not too big a deal if you have a machine shop and work for peanuts.... This design is useless for anything over maybe 10-15 FPE, of course....

Bob