QB fans – experiences with recent barrels?

[nervoustrigger]

How have the recent QB barrels been performing for you?
 
This year I have purchased two QBs.  One a .22 (AR2078 with wood thumbhole stock) and one a .177 (QB78S with synthetic stock).  Both seem to have barrels that refuse to be coaxed into producing the groups I’m accustomed to.  After running through the usual myriad of pellets, I’m getting no better than 1” groups at 30 yards and most are significantly worse.  Typically I expect multiple pellets to produce groups 1/2" or better.
 
The full manicure and pedicure treatment has been fruitless with both.  One I swapped with a known good barrel and it’s doing great now.  The other I haven’t swapped yet so I don’t want to rule out the possibility there is something else in the system at fault but I’ve looked at all the usual culprits and haven’t found anything yet.
 
In the previous 7 years or so, I probably worked on a couple dozen QBs and none of them did so poorly.  I don’t want to cry wolf but I’m starting to wonder if the changeover to Beeman isn’t producing a quality slide.
 
Am I just having a string of bad luck?

[mackeral5]

I don't have any experience with QB barrels sold after 2014 or so....

[caveman]

I haven't been too happy with anything that's had their name on it in the last couple of years. And you certainly are not gonna get any form of help from them, they don't even answer the phone or e-mails anymore. Never thought we would ever see this kind of product/service from what was once a world leader in their field. What a shame I remember being a young airgunner in awe of their exacting work back when the name had merit around the world. My how things change. Later Geno

[Toddspeed]

I got my AR2079 last summer, it’s .177 and it’s crazy accurate. I did a little work on the lead but that’s it.

[Mr. Panther]

I bought a 1085 in .22 and a QB in .177. both seem to group well for me I haven't done any thing to them yet.

[atcguy1990]

I just got a QB78 Deluxe in .22...The valve seal leaked out of the box, but after going through a few cartridges with some pellgunoil its been holding gas for 5 days now. Accuracy is so-so with JSB 14.3g dome pellets. Silver dollar size groups at 30 yards, standing, with open sights. I expect it will improve once i get some more practice in, and go through it.  I think i feel a transfer port seal leak when i shoot it too, that needs to be addressed. Will report back once i put my scope on it this weekend. 

[Back_Roads]

 I got 2 1085s in the last 6 months .177 and .22 both live up to their reputation 

[nervoustrigger]

Thanks guys, I guess I just had the misfortune to get two bad ones in a row.  Certainly has shaken my confidence, and that may have as much to do with the good luck of previous years as it does the bad luck of this year.  I’ll report back when I get the latest one sorted out.

[Mr. Panther]

I thought my luck was bad with these things LOL. Hope you get ti worked out. Let us know what it was if you do.

[nervoustrigger]

Quick update.  I swapped the suspect barrel on the QB78S with another OEM barrel.  It was an untested one but the rifle started turning in decent groups so that was the confirmation I was looking for.

Before repurposing the original barrel as a tomato stake, I decided to try working it with a poured lead lap.  So I took a bore mop and used a torch to burn off the cotton, leaving just the wire frame to serve as a lattice for the lead.  Then I heated the barrel and poured in some lead.  Here's the resulting lap:



Once it cooled, I pushed it proud of the muzzle (taking care not to let it fully exit) and slathered it with a slurry of J-B and a more aggressive polishing compound and began working it back and forth.  I could feel a slight restriction near the end of the barrel that opened up just before the muzzle.  I kept working this tight spot until it was blended with the rest of the barrel.

Previously it was a miserable scattershot but now it's grouping a variety of pellets.  For example the RWS Supermags are now holding 1/2" groups at 30 yards:

[mackeral5]

Nicely done, and just enough details for me to understand  the process.   I have a couple of
177 QB barrels that I may have to try this on.  Thanks for sharing.

[nervoustrigger]

Good or bad, please let me know how it goes.  I'm going to revisit the .22 barrel soon and see how it goes, so I'll report back on that when I do.  I think if I can't detect a loose or tight spot, I'll probably abort the mission because the general surface quality of the bore already appears to be pretty good.

One thing about the method I neglected to mention was that I was periodically giving the lead a couple of taps on the end to swell it out whenever I could feel its contact diminish with the bore.  For that I used the blunt end of a close-fitting transfer punch (an 11/64" for .177 cal).  Since it would be going into the muzzle end, first I smoothed its shank with 400 then 600 grit wet/dry and buffed it on the polishing wheel.  When tapping on it to swage the lead lap, I took reasonable care to drive it straight...that is, not introduce any lateral forces that might alter the ends of the lands at the muzzle.  But knowing that's a possibility, I went ahead and dressed the crown again with the brass screw method. 

Side note, this set of transfer punches is one of the most used tools in my shop.
https://www.harborfreight.com/28-piece-transfer-punch-set-3577.html
Besides their stated purpose, I'll often wrap one with wet/dry sandpaper for polishing a barrel leade or a receiver where the bolt slides.  Or use one as a mandrel to spin an O-ring in the drill press and alter its OD slightly with a rubberized polishing bit in the Dremel (comes in handy when needing to make, say, a metric M2 O-ring from a -0xx O-ring).  On several occasions that trick has allowed me to get guns back up and running the same day rather than waiting days for O-rings to arrive.

[Ribbonstone]

Old-school lapping....good description/good way of making a little lap.

Lot easier to go a bit too far,but it certainly gets the job done on tight spots.

Think they use what are basically QB barrels on more airguns than we think.   Certainly seems they start out from the same place for a whole lot of China made rifles.

They did get better over the years....lasts ones didn't need any attention (two Chiefs,a 1085).Might have gotten lucky.

[grand-galop]

Magic happening once again under your fingertip....
Good job and thanks for sharing...

[mrbulk]

Hey Jason what length are your barrels? I may have something to add if it's the same as what I'm thinking...

[Sbak]

Just throwing it out there for those who might be intimidated by casting a barrel lap, but you can make a lap with a bullet pretty successfuly as well. Just Chuck the boolit up in a drill press and drill a hole all the way through. Put it on the end of a bore cleaning rod with a brass screw. You can tighten the screw to "bump up" the diameter of the bullet as needed.

[Phoebe]

To answer original question I just received a QB78 Deluxe last week. I have around 600 shots thru it and it's always inside a half inch at 25 yds (w/JBS .177/7.33). I'm getting +/- 670 FPS which is better than expected.

Fantastic shooting gun.

[nervoustrigger]

Alain, thank you sir!

Charlie, these are all OEM length barrels...a bit over 22" overall counting the loading tray.

Shane, that's a good tip about using a bullet.  I briefly considered doing that but I didn't have any .177 slugs   Turns out a poured lap was actually pretty easy though.  I've melted lead on the stove (with the vent sucking out the fumes) but then I remembered I have an old solder pot so I used that instead.   Plus I figured making it somewhat long would make the job go quicker by helping it to carry more abrasive into the bore.

 

[subscriber]

Jason,

I think the long lap helps bridge irregularities and pick up average alignment and twist better than a short lap.  The latter can tip and wander more where the bore is loose.   

Yes, initially a long lap in a large caliber can take a lot of force to move.  Clearly you did well with yours.

Am I the only one to consider Jason's used lap image a thing of beauty?

[nervoustrigger]

Well I tried a poured lap on the .22 barrel and noticed some slight lack of uniformity based on resistance but it wasn’t as pronounced as with the .177.  I went ahead and worked it until it felt consistent all the way through, then recrowned it for good measure.
 
The result?
 
Garbage.  Won’t group anything I fed it.  It’s really a mystery to me.  Pellets feel fine on the way through.  Engraving looks fine compared to good barrels.  Sometimes it seems maybe like a harmonics issue so I tried it with and without a barrel band, with and without an LDC but the results are always bad.
 
Right now the QB is wearing a .177 from an old BAM B50 that groups great and I have no reason to fool with the OEM .22 any more other than it just bothers me that I can’t identify why it’s so bad.  Reminds me of Vigilandy’s from a few years ago…lopping off a bit from the end totally transformed it so I may try that as a last-ditch effort before using it as a tomato stake in the spring.