QB78 barrel good or bad?

[iconoclast]

I was reading some past posts about tuning the QB78.
In one post mikeiniowa states "first thing is to make sure it has a good barrel"
How does one determine if a barrel is good or bad?

[Jaymo]

Ive been wondering the same thing myself.

[ribbonstone]

Only way to know for sure is to shoot the rifle once you get it.  Clean it of the gunky preservative they use in the bore (and all over the outside of the rifle), gas it up, and shoot a few groups.  

Won't shoot it's best just out the box, but will shoot well enough to show if you've got a good barrel or one that scatters shots like a 12 ga.

[iconoclast]

So I guess you are saying to set up a test firing with a bipod or sand bag.
I've also read that using the wrong pellets can cause scattered shots.
So, I would imagine that one should use premium pellets such as RWS superdome or JSB exact to eliminate pellet problems.
What test results should one expect from a good barrel?
What test results would indicate a bad barrel?

[ribbonstone]

I just use sand bags and a solid table rest.  It's not a springer, so you can bed it down firmly on sand bags to no ill effect.

My shop bench is 20 yards to my test target backstop, so that's the range I tend to use for comparison.  Good QB barrels will shoot 5 shots iunder 1/2", averaging about 1/3" with the pellets it likes best.  Hard to predict what pellets it's really going to like, but I'd test whatever you have on hand.  Ideal would be a high quality wad cutter (H&N or RWS)...medium weight round nose (CP or Super Dome)...heavy weight round nose (CPH or Kodiak).  If you have JSP's, then certainly test those as well.

Might need a second cleaning.  That preservative finds its way into everything, and it's not unusual for a new gun to cough up some "air gun snot" from some out of the way spot in the first few shots.