Burr in QB barrel, what to do?

[NHGuide]

SO. a LONG time ago...three houses back, I bought a QB79 in .22 with the intention of doing a few of the Bob Sterne mods...the $200 PCP thing.
it sat, and sat.  Never did a thing to it, never shot it. Honestly, I can't remember where I even bought it.
I finlly got around to pulling it apart and putting a QB 78 tube on it, 'fixing' the valve and all that fun stuff.

WELL. 
initial reassembly went well, just to test the whole thing... so I though I'd clean the bore since I had never done that...right where the rear sight screws are tapped, (one of them, anyway) my cleaning patch got bound a little.
upon inspection I saw a sand-grain sized bump.
I pushed a pellet through.
wow. a gouge the size of the grand canyon. I scoured the 'net' looking for a solution and all I can think of is replacing the barrel.
   It's looking slim for the .22 caliber barrels out there...exceptfor an outft in the UK that would cost nearly a hundred bucks to own after shipping, et al.

I'll post a Want To Buy here on this forum but does ANYONE have a different solution to this?

I can't think of anything that won't ruin the barrel further.

[Tweeter]

Wow, I've never seen anything like that!  Too bad you just noticed it now because that would for sure be a warranty issue...   PM sent.

[SpiralGroove]

.......right where the rear sight screw is tapped, my cleaning patch got bound a little. upon inspection I saw a sand-grain sized bump. I pushed a pellet through.
wow. a gouge the size of the grand canyon. I scoured the 'net' looking for a solution and all I can think of is replacing the barrel. I can't think of anything that won't ruin the barrel further.

- So the bump is at the breach -> Right?

Just use a diamond bit on a Dremel and grind it down and smooth with 500/1000 grit paper, then use JB paste.  Since the issue is not at the muzzle, shouldn't be a problem.  The rifling after the bump will guide the pellet just fine.  Check your crown while you're at it - may need a clean up.

[NHGuide]

Kirk,
 The bump/burr is under the setscrews for the rear sight...about 7 inches down the barrel from the breech. I don't have a bit with a long enough shaft to reach.
I THOUGHT about knocking it off/out with a steel rod...I tried briefly with an old beat up .22 aluminum cleaning rod, to no avail... but figured that would bugger up the pellet even more.
The crown actually looks pretty good...."so I've got that going for me...which is nice..."

but I guess there's nothing to lose if I get in there with SOMETHING to knock it flatter, eh?

[Grampy ray]

Looks like a  hanger burr from drilling the transfer port hole with  to much down pressure ? If it is I have used a super fine round  micro file   to knock it down pull it into the hole not away .then tiny oval dremil bit in a drill pen go slow just useing part next to the shank to do a micro reverse counter sink on it to get it off. Put a backer strip to protect the other side of the bore while you do it.

[Grampy ray]

Oops posted too slow.

[Grampy ray]

For a too deep hole for the sight you might need a new barrel.

[Taso1000]

Will,

Does the tapped hole go all the way through the rifling?  Maybe you can remove it the burr going through the screw hole with a diamond or carbide deburring tool?

Taso

[Gippeto]

Shoot it first....don't know if it'll group until you try.

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If it's a shotgun, there's no warranty, and nothing left to lose....and you WANT to spend the time playing with it.....

With nothing to lose and time to burn, this is what I would try;

Use a steel rod and knock the burr off. It WILL damage the rifling a little, but it's 7" down the bore...

After you knock the burr off, push a pellet through and see what it looks like. Try some groups.

Acceptable....have fun.

Still a shotgun, still gouging the pellets and still have spare time to experiment....

Would wrap some 1000grit wet/dry sandpaper around a cleaning mop....lube with light oil. Mark the cleaning rod so you don't sand more than a couple inches past the burr on either side. Clean and push a pellet through every dozen strokes or so to check the progress. Try not to sand the chamber area more than absolutely necessary.

Going to create a loose spot in the bore, but find barrels will usually shoot fine with a loose spot so long as it's not at the muzzle.


Al

[NHGuide]

Taso, Al,
 BOTH good ideas.
 I have plenty of other rifles ...this is a project gun...so plenty of time to play.
I like the simple idea of the steel rod and then some fine grit on a mop...

in the weeks ahead I'll post what I find....who knows...maybe it'll be a 'new' way to 'inverse-swamp' an airgun barrel and I'll start a new fad 

Thank you guys for the ideas!

[chuckinohio]

  You should be able to get a .22 barrel here in the US.

  Voldemort shows them in stock. You will have to do some Google work to find them, but they are like 40 bucks or so.

[Taso1000]

  You should be able to get a .22 barrel here in the US.

  Voldemort shows them in stock. You will have to do some Google work to find them, but they are like 40 bucks or so.

Voldemort??  I see what you did there.  Nice!   

Taso

[chuckinohio]

  You should be able to get a .22 barrel here in the US.

  Voldemort shows them in stock. You will have to do some Google work to find them, but they are like 40 bucks or so.

Voldemort??  I see what you did there.  Nice!   

Taso

  I am actually watching  'Chamber of Secrets' right now oddly enough.........

  I assume he is still un namable as before.

[NHGuide]

Good one Charles... I might call him tomorrow. But not speak the name...

I looked all over that website and the exact 15mm diameter barrel in .22 is out of stock in all the various incarnations....well apparently except if I wanted a multi shot breach and all that....which I don't. I think his cost is about 46 bux-ish.

I think I will attempt the steel rod knockout punch thingie. then smooth it out... what is there to lose, really?   and then may buy another barrel to have 'in stock' as it were...in case the first method creates the dreaded shotgun pattern like Gipetto says.

But it's all in the name of puttering.

Y'all are good people, here. Thanks for the comments and ideas.

[Tweeter]

  You should be able to get a .22 barrel here in the US.

  Voldemort shows them in stock. You will have to do some Google work to find them, but they are like 40 bucks or so.

Voldemort??  I see what you did there.  Nice!   

Taso

  I am actually watching  'Chamber of Secrets' right now oddly enough.........

  I assume he is still un namable as before.

As unnamable as ever.     Why not just buy a used complete .22 and then you'll have extra parts?

[Gertrude]

You might want to PM Bob and Jason to see of maybe they have run into this before.

[gendoc]

Why not just buy a used complete .22 and then you'll have extra parts?

yes to that ^^^ then you can take that steel rod and knock it out.....50/50 

[Taso1000]

Maybe MM at FDAR has a barrel or more information?  Try shooting him an email or call him tomorrow before noon.

http://flyingdragonairrifles.org/

Taso

[rsterne]

I have never seen this, but heard of a similar issue on the Hammerli 850s, where sight holes will drilled too deep and damaged the bore.... They replaced any such barrel free, regardless of warranty period, because it was such an obvious manufacturing defect.... A letter to the manufacturer, along with your photos and a description would be your best bet....

Al's advice (Gippeto) is spot on.... and if you can't fix it, see if you can pick up a good used barrel.... or take the opportunity to get an upgrade barrel....

Bob

[Ribbonstone]

Mid barrel is a really bad spot for a burr, it's not going to be easy to get down there from either end and would be pretty easy to do more harm than good.   I'd likely buy a replacement.