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AR2078A TARGET RIFLE

March 3 2009 at 7:47 PM

  (Login BrushyBill)
YF

Greetings QB fans,
I have had an AR2078A target rifle for about a year now.
Sorry to admit it, but, after a good cleaning and lapping the barrel,
I have not shot it more than 20 shots or so.

A little disapointed with the stock fit although I was duly warned by the info
on the Archer's Airgun website. ( great people to do business with by the way, damn glad they are there)
I have spent most of this past year modding and shooting the hell out of a bulk fill co2 .22 cal QB.
But it is time to get this .177 cal going.

I have removed the stock for severe modifications; adjustable cheek piece, adjustable butplate,
extending and reforming the grip to name a few.
I have a lothar walther barrel blank for it and plan on shooting
10 meter matches with it starting this coming fall season.

BTW, the barrel will only be 16-18 inches long fully shrouded, the shroud also
being used as a sight extension tube. Using a breech riser ala Rich From Mich.
And the factory rear target sight has to go, shot too many NRA smallbore & high power rifle
matches to use one of this quality, although it does work. Will be building my own.

The club where I will be shooting runs a 60 shot standing
course of fire. 1 hr. 45 minute time limit.( pretty grueling, mentally & physically)

I only need this rifle to shoot in the 480-500fps range. using a match wadcutter pellet.
What would be the best way to "de tune" this rifle?

I am a little concerned with shot count. To be safe, I need a minimum of 80 "good velocity" shots per fill.

Would one of the long pcp tubes from Mac1 give sufficient shot count bulk filling from a scuba tank at these velocities?
I have not used pcp power yet, the bottles have a regulator in them, where does these long tubes get regulated?
( newbees, what are you gonna do with us? cant take us anywhere, cant leave us at home alone, and we got all these silly azzed questions )

I have a short tube and bottle block that I can put on this rifle.
would a 13 cu in tank from JDS Airman regulated to 850 or 900 psi give me 70-80 consistant velocity shots?
The 22 cu in tanks are only four inches longer, and cost the same I believe.
To maintain the looks of the rifle, I would prefer to use a tube from Mac1.
But will do what I have to do.


I need some experienced input on this.

I have heard the expression on this forum "making a silk purse,,,,,"
but what the hell, from what I have seen, these QB,s are the Mauser's of the airgun world.
And I believe in my heart that I can make this rifle shoot with the accuracy I need.
And have a great shooting target rifle, as long as I can get the shot count where I need it.

And thanks, I know someone will recommend the 850's,
they are an incredible rifle and I will own one soon, but I want a single shot target rifle.
( that I have put together, I am sure most of you can understand)

 
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AuthorReply

(Login ptrasatti)
YC

Start here...

March 3 2009, 8:06 PM 

Bill,

Take a look at this thread on HPA and QBs.

http://www.network54.com/Forum/113813/thread/1234860249/Running+a+QB78+on+air.+Got+a+question

I believe that the MAC1 extension tube is not regulated and just adds volume and is for C02. For shooting with air you need a regulated bottle or go to a PCP tube. I would assume that with the larger (22cu in) bottle you would get 60 shots. Robert is the QB HPA expert here and I am sure he will help you out with these details.

Search this forum for "QB mods" "QB PCP" and "QB HPA"

You should find a lot of postings.

Good luck,

Phil in NH

PS: BTW, I am a newbie too. Been playing with QBs for about 2 years. AR2078 on CO2 and a Jack Haley QB 78 PCP. I get 30 good shots @ 2250 psi in my QB 78 PCP. I don't have a chrony so hard to tell if the fps is consistent.

[linked image]


    
This message has been edited by ptrasatti on Mar 3, 2009 8:12 PM


 
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(Login gubb33ps)
YF

think a search would turn up...

March 3 2009, 9:27 PM 

..a whole bunch of things people have done. Yes, you can get one running on a 13CI bottle, using a QB79 tube (and adjusting the stock to match) would not require any metal working to get assembled. I went ahead and moded the existing full length tube in order to have the full length stock.

800-850PSI will still run a bit faster than warm weather co2, but it's a pretty good pressure to stay at.

To get the best the rifle had to offer, I slowed it down a bit (low to middle 700's).
http://www.network54.com/Forum/113813/message/1235244473/Preaching+to+the+2078+choir


    
This message has been edited by gubb33ps on Mar 3, 2009 9:31 PM


 
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Bentong
(Login Oragon2)
YF

Good Info's

March 3 2009, 9:40 PM 

Saw this a while back and got some good information on bulking/tuning the QB's >> http://www.kermitairgunclub.com/qb78contest/entries/

 
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(Login peterdragin)
YF

AR2078 target

March 3 2009, 9:55 PM 

Here's mine. It's a 2078 stock modded to use the 9oz bottle, adjustible cheek piece, LW 177 barrel, high rise breech and full 1 1/8 diameter shroud "very quiet", mild valve job shoots superdomes to a cloverleaf hole at 25 yards at 690 fps and gets hundreds of shots per 9oz bottle.

 

2078AA.JPG 

 

Here's the latest one I made and it's a .20 on 1050 psi HPA shooting 11.4 fts's at 840 fps, gets a few over 90 shots per fill.

 

tackB.JPG 



http://home.comcast.net/~peterdragin/index.html/

 
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(Login BrushyBill)
YF

Thanks

March 3 2009, 11:06 PM 

Rich,
Love your work. (But wish you could have time to update photos on your
web site a little more often, I have worn out the ones there now just looking at them)

I believe the HPA is the way to go as the indoor range that I will
be shooting this at in the winter is heated, but will probably be only
be around 60 deg if we are lucky.

If you are getting 90 shots with a .20 cal. I should have no problem
running the 22 cu in bottle on the .177 cal. and most likely will go
in that direction, only sticking around 900 psi regulated.

My .22 QB came in as a 9 oz bottle fed rifle, even after the mods
it seemed as if you could shoot it forever. Wanted to go with a thumbhole
stock and am now bulk filling a longer tube.

I actually like the co2, but feel that I need to go with the
HPA on this .177 cal and the .22 that I am getting ready to build from
scratch / parts. ( need a hard hitting cold weather rifle, the wabbits are getting thick here
and the freezer has extra space)

My main question is once I get this rifle set up to start shooting through
a chrono, how is the best way to slow the fps down to the 500 fps mark?
I have read in here where guys are lightning the hammer & or hammer spring? after doing the
valve mods & porting, to help increase the gas effiency.

I can see how this would work, seems to me that they are just decreasing the time
that the valve is open. ( dwell?) And by using a chrony, they can monitor their fps and stop when
the speed starts to decrease.

This sounds like the direction I need to take on this project. Only go farther than they do because I
don't want this to shoot at 900+ fps.
Does this sound practical to you?

I was not going to go through the porting and valve mods on this rifle at first, but am now
reconsidering this as I think it would help to get as much air to the pellet as quickly as possible.
Even though I am not wanting maximum velocity.
Thanks for taking the time to read and post your comments, it helps us all here.

 
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(Login gubb33ps)
YF

Re: Thanks

March 3 2009, 11:19 PM 

So far, the best way to get one shooting slow and still consistent, has been a lighter hammer, slightly lighter spring, and a more restrictive transfer port.
[IMG][linked image][/IMG]

The light hammer will be moving faster and has a bit less friction, so it kind of jabs the valve rather than clobbers it. Benefit seems to be that the jab is more consistent (the percentage of energy wasted in friction seems more stable than with a heavy slow moving hammer). Even when spring tensioned back up to the same speed as a heavy hammer, the shot count is a little longer and the rifle a little quieter (valve dwell?).

Strangling the gas flow with a smaller inside diameter transfer port does work...and does seem to extend shot count. Wish there was an easy way to put in a transfer port adjusting screw (a strangle screw), but unless using a riser breech, there just isnt room', so be ready to make a couple of transfer port seals with different internal diameters until one is near enough to the vel. you want that you can get to it by slight spring tension adjustments.

 
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(Login timhsieh)
YC

just saw a fwb c62 at aoaused page.

March 3 2009, 11:21 PM 

if you want a world class 10m co2 rifle for not too much money

[linked image] [linked image] [linked image]

 
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Rich. from Mich.
(Login peterdragin)
YF

thanks

March 3 2009, 11:27 PM 

I am building a new web site but it's hard getting the time to finish it.

I would just leave the valve stock and even the bolt stock and on 900 psi it should be just about right and get huge shot count on a 22 ci tank.

www.richinmich.com  is the new site and some pages are up and more on the way.

 

Her's another of my hot rod QB's. There is not much QB left only the trigger, .20 cal 3000 psi and 28 FPE with 11.4 FTS's.

cocrancustomB.JPG 
http://home.comcast.net/~peterdragin/index.html/>



    
This message has been edited by peterdragin on Mar 3, 2009 11:30 PM


 
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(Login BrushyBill)
YF

Thanks Robert & Rich

March 4 2009, 12:07 AM 

Robert, makes sense. what you said, it goes along
with what Rich suggested by not doing the valve mod.
Gonna let all this soak in, I believe I have a direction now.
Just gonna have to see what the chrony tells me after its together.

I do appreciate everyone's input.
This is indeed a great place.

Will take pics and post along the way on this adventure.

Rich, I had already bookmarked your new site 3 or 4 days ago.
Keep cranking out those work of art rifles of yours.
I love eye candy that actually shoots good too.
( And didn't come straight out of a box)


    
This message has been edited by BrushyBill on Mar 4, 2009 6:23 AM


 
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Garrett
(Login gmany)
YFOT

Why not use CO2 ? -nt

March 5 2009, 9:10 PM 

garrett

 
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Bruhsy Bill Roberts
(Login BrushyBill)
YF

winter

March 6 2009, 10:58 AM 

The club matches for 10 meter Rifle & pistol
are held from 0ct thru april.
The indoor range here in Columbus Indiana is
heated, but we are lucky if it is 60 degrees in there.
and transporting the rifle to the range, it may be 10 below.
Just don't want any temperature issues with co2.
I believe you may be right, it may not be a problem,
just don't want to take the chance, The block I will
machine to accept the 22 cu in tank will also accept
a 9oz paint ball tank. I can try the co2, if there are issues
I can install the hpa tank regulated to 900psi with
no problem.
The (in here considered slow) fps ( 500fps)I want this rifle to
shoot wont be a problem with either.
Thanks for your input.


 
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robert
(Login gubb33ps)
YF

Do convert back to co2...

March 6 2009, 8:24 PM 

...once the temperatures are expected to stay in the 70's and 80's. Down here, that's right about now, and I will be reconverting at least 2 of them from HPA back to co2.

 
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