QB78 pull down help

[Dukemeister]

I have the AR2078 mostly apart - but I can't get "0200" plug out of the tube - it seems to be catching on a threaded hole with burr in the tube, or something. I read a tuning guide that says these may be tight and to work it out with a punch through the slots. So just to be sure, this "plug" comes out the rear end of the tube? and the valve, unscrews and comes out the front end of the tube? and how much beating on this plug is allowed? OR..... can I slip it out the front of the tube more easily with the valve out?

Transfer port seal was kinda rough, and lots of "slivers" found throughout - glad I'm doing this. Thanks!

[jpsgunworks]

It will go out the front if you loosen the valve halves .The two parts of the valve don't have to be totally unscrewed, just enough to take the pressure off the o ring. Silly question
but I assume you have taken the breech screw ( part #1700) out as this screw goes into the top of the plug.

[Dukemeister]

Hi, thanks. Yes, it's all apart except for the valve and the plug. I just read TR Robb's strip down and he does say the plug will go forward too, so I won't be going at the plug with a hammer and punch. I will need to make a valve removal tool tomorrow.

[SeanMP]

My plug wont go out through the back either, I have to slide it out with the valve.

[AirGunEric]

I have the AR2078 mostly apart - but I can't get "0200" plug out of the tube

I assume you are looking at a QB78 parts list? The AR2078 lists the QB "0200" part as AR# "2500" ?

Either way- you take take it out either end of the tube if everything else is out of the way- but once it's out- get rid of any burrs it might get caught on (i.e. the threaded hole you mention).

[remtom1200]

LoL... the only tight thing on my qb78d was the valve as I tore it down. Not a few, but every bolt was untightened including the sights. Must have been a Monday morning special. Cant wait to polish it up and put it together properly.

[Dukemeister]

LoL... the only tight thing on my qb78d was the valve as I tore it down. Not a few, but every bolt was untightened including the sights. Must have been a Monday morning special. Cant wait to polish it up and put it together properly.

Same with my AR2078, no tight threads anywhere, not even the valve... I took it out with a strip of 1/8"x5/8" pine... it literally fell out of the tube with a 1/4 turn. The white O-ring seal was pretty chewed up too.
I have replaced it with a black O-ring from the kit, Eric I guess this is the right one for that spot since the white O-ring went on the filler cap?
Anyhow, it's in the garage "chillin'" and I will test fill it in a half hour or so. Seem to feel a lot smoother cocking and dry-firing - I have polished up all the internals. If it holds, I will be sending lead downrange before 10:30...

[SeanMP]

Awesome...That's the best part!

[Dukemeister]

OK.... it holds perfect, cocks smoothy and shoots darned fine!
Thanks for everyone's help. I mounted the Fitco 6-24x40 scope, because I had to....
Here it is, with custom big bolt!
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[SeanMP]

Thats great news Duke.

How is the group size since the de burring?