GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: nervoustrigger on November 11, 2020, 12:21:51 PM
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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?
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I don't have any experience with QB barrels sold after 2014 or so....
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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
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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.
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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.
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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.
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I got 2 1085s in the last 6 months .177 and .22 both live up to their reputation :-\
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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.
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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. :)
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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:
(https://www.gatewaytoairguns.org/GTA/MGalleryItem.php?id=7581)
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:
(https://www.gatewaytoairguns.org/GTA/MGalleryItem.php?id=7582)
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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.
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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 (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.
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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.
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Magic happening once again under your fingertip....
Good job and thanks for sharing...
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Hey Jason what length are your barrels? I may have something to add if it's the same as what I'm thinking...
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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.
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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.
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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.
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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?
(https://www.gatewaytoairguns.org/GTA/MGalleryItem.php?id=7581)
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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.
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Going to dump on you...seems like a good place to get most of the QB thoughts out of my system without starting a new post on the same topic.
MAy not be a help to you, perhaps a help for others reading along.
HAve had a few bad ones back in time....yours is one of the few new ones I've read about from a reliable poster having a problem for awhile (some other posts, but not so sure there weren't other problems going on that failed to get looked at).
Going to lump all QB barrels. THe old "skinny"QB barrels (the 14mm version used on the orginal 78) and the "fat"QB 15mm versions used on the 2078/79,and 78D's.
In the last two years, 3 new QB barrels (going to count the ones on the Chief's as well as a QB co2 repeater),no complaints about them. Do notice that the Chief used the "skinny"diameter.
One old .177 did have a problem.... got saved by cutting to carbine length...the tight spot was about 3.5" back from the muzzle. Had typical visual problems of the time(the bore wasn't dead-on center after it was cut),but still use that barrel as it shoots really well.
One .22 I just never figured out. LIke yours, nothing I did made any difference, and there wasn't anything I could point to for a reason. Looked good,felt even when slugging (or lapping), recrowning didn't help. Even whent so far as to cut off the breech end, machine it, make bushings,and try it in an AirForce Talon....still shot crappy.
(Idea above was that if it shot well in the AirFoce with it's new breech...I'd cut it again and make it work on the QB as a carbine cut from the rear end. It didn't, so I didn't, and it is still doing duty as a rusty garden-stake.)
HAd a good spare .22 QB (fat) barrel from a rebarreling project (5mm),so cut that one from the front to carbine and used it on the QB79 HPA conversion.
REBARRELING:
Rebarrling for me is a bit more labor intensive as I don't have a mill...did have a lathe for the shank diameter. With with time and effort,can make the loading platform with a grinder and files...or even a hack-saw and files.
OR you can make a detachable loading platform (black Delrin will work)and leave the barrel "flat breeched". Remove the platform, de-top the QB without having to remove the barrel from the receiver.
THOUGHT that joining the barrel and reciever solidly might help. Good idea in theorythat didn't work in practice; abandoned that.
Did find along the way that it helps to "spot in" the reciever to gas tube. Basicaly paint it with lay out blue (or lipstick...or soot if you got nothing else..something that easily transfers)to see if it sits down with a large contact area...or if it's teeter-tottering on a couple of high points.
(I'll do that on more expensive rifles as well...that does seem to help stability if not accuracy, but usally both.)
Two rebarrel QB's (one with an HW 5mm blank,other with an LW.25 blank) they shoot real well. One outtthe box QB barrel and one cut-down/worked over QB barrel group just as well.
QB "swingers" club:
If you have more than one QB,can often swap barrels/bolts(or even the whole "upper"assembly). If a suspect barrel then shoots great,probably not the barrel at fault. If the suspect barrel still shoots crappy on the known to be good rifle, probably is the barrel's fault.
Used "probably"...could be some other glitches going on.
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So thinking back...maybe 13 QB barrels (counting 2 Chiefs) that I seriously worked on.
9 in the good-excellent level. Alot of that deals with both expectations and actualy uses.
2 that took some crowning,cutting,or polishing to get there.
2 that were just turds.
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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.
Did your barrels come with any front sight mounting for screws ?? I had an experience once when factory tapped barrel for front sight it caused dimples inside and pellet was impacted/thrown off...
(850 Air Magnum .177)....several owners affected.
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Hi Robert, regarding your comments about other reported “bad barrels” over the years, I agree. Certainly not just QBs but barrels in general, often times there isn’t enough information in a forum thread to confidently lay the problem at the feet of the barrel. In some cases the owner probably knows and just couldn’t be troubled to chronicle all the troubleshooting drudgery. Otherwise usually a barrel swap absent of any other changes is taken as proof positive, but even in that case there is a chance that disassembling and reassembling unwittingly fixed something subtle. We’re usually just happy that it’s fixed so we’re not likely to put the “bad” barrel back in to see if it’s still bad. However in my most recent example, the same action has now seen 5 different barrels, some of them through multiple disassembly/reassembly cycles and the issues consistently followed the two suspect barrels.
What had me scratching my head was the long happy streak of good to excellent QB barrels, that I just couldn’t reconcile the odds of getting two bad ones in a row. Especially since they were different calibers so it’s not like they were from the same manufacturing run.
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Crazyhorse, thanks for the reminder about the front sight screw. I didn’t detect a restriction there when pushing pellets through. Also I’ve spotted that type of defect before by the way light bends when looking through the bore and I didn’t see that either. I’m going to take another look though because it’s quite possible that was the case with the .177 that I coaxed into working with the lead lap. There was a restriction just before the muzzle so that might have been the location.
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Good catch....I forgot about the screw holes.
Going to have to check...but I remember QB78's and 79's as having screw attached front and rearsights. YEah...of the ones that didn't get a rebarrel,only the AR2078 didn't have screwholes.
Did have some holes drilled too deep...and some that weren't quite throught, but the screws were too long....could check it at first...go nuts on the mounting screw and find a problem later.
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Hi Jason, I just got a new QB79. When I test it out I will let ya know how the stock barrel performs. Ive been lucky so far as none of mine have been bad yet.
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The one thing I couldn't do with QB's.....could never really leave them as issued.
This from a guy who sees airgun simpllisity as a virtue...and yet I compulsivley un-simple them.
Why I ended up with so many passing though....INTENDED to leave it alone (at worst,mildy tuned)...failed....bought another one with the same intention....failed....etc.
Still have that urge....know it's not going to happen.
Best I could manage was to keep 5 (jury is out on the 6th one).
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Cole, best wishes for tiny bug holes with the new rifle.
Robert, yes I can relate. QBs practically demand to be modified. So much potential on tap waiting to be enjoyed that it seems a shame to leave it be.
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I checked the .22 barrel for possible damage at the front sight screw but I had forgotten it’s from an AR2078 so it actually doesn’t have one.
However while looking more closely at the bore, I noticed a light scratch about 5” from the muzzle. Looks like a perfectly circular scratch cutting across the lands and grooves. Then I flipped it around and it turns out there is at least one more closer to the breech end. I’ve never seen a defect like it before so I have no idea how they got there. I could not feel them with the poured lead lap so I don’t know if they are related to the poor performance but it’s the only thing that stands out.
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Another "dump"...seems better here than starting a new topic.
Do think there is still a place for making QB's into something they didn't start out being.MAy not be cost effective,but you lean a whole lot about co2,HPA,PCP airguns. That carries over to whatever other airguns come your way.
THe 5 "keepers" (over the last 12 years): 9 to 60 foot pounds
(https://live.staticflickr.com/65535/48025711816_7e809a6f55_z.jpg) (https://flic.kr/p/2gaSjW5)DSCN1990 (https://flic.kr/p/2gaSjW5) by Robert Dean (https://www.flickr.com/photos/144930793@N07/), on Flickr
They all still look "QBish" to me.....one even looks kind of "stock".
Maybe the inportant part is that "12 years"...they are easy to repair, don't seem to wear out anything but the easily replaced seals.
#6...I just don't knowwhat it would do "better"than be a repeater.
Beeman 1085 .177. Jusy is out on this one. Scope sight line and the low cheek of the stock. IF I add a cheek riser (even if it's just glued on),would be happer.
(https://live.staticflickr.com/65535/48660337231_2f6c31de49_w.jpg) (https://flic.kr/p/2h8WWXz)DSCN2193 (https://flic.kr/p/2h8WWXz) by Robert Dean (https://www.flickr.com/photos/144930793@N07/), on Flickr
Stock fits better with iron sights....but not as useful as it would be scoped. But it's still pretty much un-messed with (different sights and LDC...other wise as it came out the box.)
(https://live.staticflickr.com/65535/48887376486_a9555b30b5_w.jpg) (https://flic.kr/p/2hu1zPu)DSCN2307 (https://flic.kr/p/2hu1zPu) by Robert Dean (https://www.flickr.com/photos/144930793@N07/), on Flickr
Give into the urge to change things? Have the parts to try,stock is even inletted for the tank block...everything just needs to be assembled (although wood stock would be even lower than the pastic).
(https://live.staticflickr.com/65535/49773666891_13226df2ef_w.jpg) (https://flic.kr/p/2iQk45x)DSCN2671 (https://flic.kr/p/2iQk45x) by Robert Dean (https://www.flickr.com/photos/144930793@N07/), on Flickr
Considering my past history....sure bet what's going to happen...NOT a sure bet that it will earn a place with the other 5.
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I took my new QB79 out and finally shot it. It required some messing with the front sight height, but after that it was dead on the money. I forgot to clean it and it still shot great. Almost afraid to clean it now that I have it all dialed in LOL. Took all my Oriental "girls " out today All 7 of my QB's and my three Gauntlets topped off the tanks and put fresh cartridges in the two CO2 's and had a blast . Except for the Gauntlets they are all set at 1100 psi except the heavly modified one that is set at 1175. I must have won the barrel lotto on those guns because they all shoot rather well. So out of the two newer barrels ,( both .22 15 mm) they both seem to be good shooters.
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Good going....they can be very useful/accurate just they way they are.
Good barrel is a good barrel no matter who made it.