Looking to set up my AR2078 with HPA, whats the best set up?

Looking to set up my AR2078 with HPA, whats the best set up?

Joined: April 8th, 2004, 2:24 am

July 10th, 2012, 7:42 pm #1

I've been shooting the gun off 2 c02 carts,and want to use hpa to get more shots. Whats a good set up for this gun?
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Joined: November 17th, 2006, 3:51 am

July 10th, 2012, 9:43 pm #2

If you do not have a way of generating 3000psi air and do not mind being tethered to a tank, can get shooting air for decently cheap. Can find a new 62ci 850PSI out put 3000psi HPA tank on line for about $50. Put a bulk fill end cap into the AR2078, attach a remote line, and hook up the 62ci tank. Will get about 440-490 shots before having to go back to a paintball shop for a refill of air.

No mods to the gun at all, can go back to 12gr. when you want to. Set this one up that way to run on 20oz. co2 tanks or 62ci HPA tanks. Wasn,t real mobile, but did get the job done.

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Yes..are 4500psi air tanks. But they cost about 3X as much as the 62ci 3000psi tank. Would be way ahead to buy 3 of the 62ci tanks for the price of the one 4500psi tank.

If you want the tank and the gun together in one unit, its going to require some careful work on your part...and you'd need your own way of generating 3K air to fill the little 13ci tanks.

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Will look for the how-to post...but its going to require some gun cutting/drilling.
Last edited by gubb33ps on July 10th, 2012, 9:46 pm, edited 1 time in total.
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Joined: November 17th, 2006, 3:51 am

July 10th, 2012, 10:57 pm #3

..too many pictures were no longer attached.


Old post




Have to remind you at this point, it is summer and still co2 weather.

Just in case you get the urge to cut up your QB78 tube to make a long tube tanker, Have noticed that the increased air tube size means more on deck air (air that has been pre-regulated) and the faster you can make them shoot.

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1. Electric drill and 5/32 drill bit
2. Needle files
3. Larger (8) fine flat file.
4. Emory paper
5. QB79 gas block (comes with screws)
6. Masking tape
7. Hammer and center punch
8. Hack saw
9. Ruler/yard stick
10.Normal take down tools (screw driver/allen keys/etc.)
11.Normal cleaning gear
12.Tin snips or heavy scissors.
13. Vice (padded)
Nice to have:
1. Dremel tool with cut off disks/polishing bits
2. Tubing cutter



Do your lay out, measure, and re-think anything and everything. The more you think this through, the better the results.

1. Want to start with a totally empty gas tube.

2. Tape up the end at the expected cut with masking tape. Figure the length carefullyI wanted the gas block to be inletted into the stocks for end, and something near this works out.

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3. Run a TUBING cutter around the masking tape at your chosen length (9 1/8 in this case). You are NOT cutting the tube with the tubing cutter, are scoring a line evenly all around it (the tape is just to keep the tubing cutter's wheels from scratching the blue).

If you dont have a tubing cutter to score a line into the tube, can very carefully and evenly apply two strips of tape, with a small space between the strips that space would act as you guide line.

4. Cut along the scored line. Can use a Dremel and cut off wheels or a hack saw, just STAY ON TOP OF THE LINE ALL THE WAY AROUND and it will be pretty even.

(The project pictured was done on a Crosman tube, added a cut off section of QB tube at the top to give an idea of the amount cut off of a QB78 tube for another project.)

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5. FILE the end smooth and even, here a large fine flat file works a lot better than a small file. Nice to vice it up, make it sit level. Do a lot of checking to be sure it is even.

6. DEBURR the inside and outside of the tube. Any lip/burr here and it sill slice the o-rings of the tank block. Needle files will do the job.

7. Cut two 1 1/2" long by 1/4 " to ½ wide strips of Al. beer can (or Coke can).
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8. Punch two small holes in one end of each Al. strip. Want the holes to be a reasonably small in size.
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9. Lay them so that the punched holes line up with the tube mounting holes on the gas block (can run a nail though the block and through the holes on the Al. strips to hold that end in place I used a close fitting allen wrench) and tape the strips FIMRLY to the gas block.
[[/IMG]

10.Insert the taped up gas block into the gas tube. Take CARE that the top of the tube is really "up" and the gas block hangs down....won't do to have the gas block at an angle.

11. The two Al. strips are on the outside of the gas tube...the holes are in the right spot for the threaded holes in the gas block...so mark the tube with a punch through those holes in the AL. strips.
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12. By using a punch, you get nice starting dimples for the drill.
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13. Remove gas block and drill the tube for the mounting screws (want the hole to be close to the screw size). The common size that is a close fit (closer than the factory holes in a QB79) is 5/32.

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A drill press would make this pretty easy, but you can do it with an electric hand drill. Need to vice up the tube (PADDED please, and not so tight that you ruin it). Just take a lot of care to be sure you are straight vertical when you drill.

14. Deburr the new holes on the inside of the gas block, they will cut the o-rings of the block unless smooth. A partly round needle file, followed by fine emery cloth does the trick just fine. Dremel and a Curex tip would work faster and smother in this case.

15. STOP! the tube is done. CLEAN IT clean it again really clean it. One metal shaving is enough to shred the valve stem seal, so be sure everything is clean-clean-clean.

15. Take the tape and Al. strips off the gas block. Lube the gas block's o-rings with silicon grease and insert it into the tube. The holes should line up if you took care with steps #9-#12.

16. The mounting screws are there just to keep the gas block from shooting across the room, they don't "seal" anything, so don't crank down on them extra-extra tight our you'll just raise burrs on the inside.

Actually, if you over tighten enough, you can cause a leak. Its a round tube, and if you over tighten, will compress the tube in that direction, which lets it gap open in the other direction.

17. Because of the distance the HPA tanks fill nipple and gauge stick out, will need to attach the gas block and the tank BEFORE putting the breech/barrel back on. OR you can attach the HPA tank to the gas block BEFORE you put the gas block onto the tube. either way.

18. Reassemble and test.

19. I like to use a brass RAP 4 (have a large inventory online) on/off. Its gauged to read the gun side of pressure, so with HPA you can check the out put (and it has a burst disk safety nice to have one more between the tank and the tube).
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20. Recommend replacing the stock valve with one with a Delrin valve stem., but have had stock valve stems hold up for quite a long time. As you will not be piercing 12gr., get rid of the piercing parts.

Simple tanker valve (minimal parts and no piercing assembly):
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Joined: June 21st, 2009, 8:05 pm

July 11th, 2012, 1:31 am #4

I've been shooting the gun off 2 c02 carts,and want to use hpa to get more shots. Whats a good set up for this gun?
I got one of his tubes and I am happy with it. Swaps out in short order.

http://www.cafepress.ca/AK47andmore
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Joined: May 18th, 2003, 8:18 am

July 11th, 2012, 7:57 am #5

If you do not have a way of generating 3000psi air and do not mind being tethered to a tank, can get shooting air for decently cheap. Can find a new 62ci 850PSI out put 3000psi HPA tank on line for about $50. Put a bulk fill end cap into the AR2078, attach a remote line, and hook up the 62ci tank. Will get about 440-490 shots before having to go back to a paintball shop for a refill of air.

No mods to the gun at all, can go back to 12gr. when you want to. Set this one up that way to run on 20oz. co2 tanks or 62ci HPA tanks. Wasn,t real mobile, but did get the job done.

[/IMG]

Yes..are 4500psi air tanks. But they cost about 3X as much as the 62ci 3000psi tank. Would be way ahead to buy 3 of the 62ci tanks for the price of the one 4500psi tank.

If you want the tank and the gun together in one unit, its going to require some careful work on your part...and you'd need your own way of generating 3K air to fill the little 13ci tanks.

[/IMG]

Will look for the how-to post...but its going to require some gun cutting/drilling.
I run a setup much like Robert's first photo. Since it has been a good number of years since HPA became common with paintball setups, there are tons of used tanks with regulators being sold on ebay and Craig's list as many outgrow that hobby.



"If you can't find the answers your seeking, change your question"
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Joined: April 8th, 2004, 2:24 am

July 11th, 2012, 2:11 pm #6

If you do not have a way of generating 3000psi air and do not mind being tethered to a tank, can get shooting air for decently cheap. Can find a new 62ci 850PSI out put 3000psi HPA tank on line for about $50. Put a bulk fill end cap into the AR2078, attach a remote line, and hook up the 62ci tank. Will get about 440-490 shots before having to go back to a paintball shop for a refill of air.

No mods to the gun at all, can go back to 12gr. when you want to. Set this one up that way to run on 20oz. co2 tanks or 62ci HPA tanks. Wasn,t real mobile, but did get the job done.

[/IMG]

Yes..are 4500psi air tanks. But they cost about 3X as much as the 62ci 3000psi tank. Would be way ahead to buy 3 of the 62ci tanks for the price of the one 4500psi tank.

If you want the tank and the gun together in one unit, its going to require some careful work on your part...and you'd need your own way of generating 3K air to fill the little 13ci tanks.

[/IMG]

Will look for the how-to post...but its going to require some gun cutting/drilling.
I have a few pcps,and thats what I use to fill them up, I also have a Hill pump for back up.
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Joined: November 17th, 2006, 3:51 am

July 11th, 2012, 9:09 pm #7

..will work nicely.

There is no free lunch...regulated guns do get a lot more shots per fill, but take a lot more air to refill. If you were running with a 1000psi regulator, a fill would be about 2000psi of air (from 3K to 1K)...which is about 136BAR.

Typical unregulated PCP will run right for about 50BAR.

So while HPA may give you 2 or 3 times as many shots, will take 2 or 3 times as much air to do it.
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Joined: December 5th, 2008, 8:43 pm

July 13th, 2012, 1:30 pm #8

I got one of his tubes and I am happy with it. Swaps out in short order.

http://www.cafepress.ca/AK47andmore
The problem using a tube is it's unregulated,
I have a .22 qb79 running on 13ci bottle, I done the usual internal mods ,
I fill it to 2000 psi and get 110 shots starting at 584 fps and it gradualy raises to 601 fps ,
a difference of 17 fps over the 110 shots,
this leaves 1000psi in the tank , so it makes for very easy pumping ,and is very consistant ,
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