After Polishing Barrel With JB Paste

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so you shot from a tin and it grouped good , then you wanted it better so you polished it now it wont group with same ammo ? if so , the crown must have a nick or blemish , paste wont enlarge barrel to lose accuracy ,, did you do it on a lathe? is the barrel tight and installed properly > what kind of gun is it ?
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I assume the JB treatment was done with a rod. If so, the "rodder" must exercise extreme care to not let the rod rub against the crown and/or the lands of the rifling at the breech end of the barrel. That JB stuff is a quite fine abrasive, but it can help damage a barrel if the rod rubs against those key contact points. This is especially true if the rod is a jointed one made of brass or aluminum. The joints, along with the soft metal, collect the abrasive so that it becomes an instrument of destruction. Bottom line: Don't let a jointed rod in the same building with a prized gun barrel.
 
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I’ve never understood how a dirty GOOD barrel can shoot better then a clean one. Or how you could damage a barrel cleaning it unless you do something really stupid.

I know it happens or seems to happen but it doesn’t seem to make much sense to me technically.

Oh I can see if you have pitting or damage a certain amount of fouling might fill in the defects but other then that 

In this situation I’d be looking for other causes . After shooting a few shots and getting those results I’d look at the scope and other things before I’d settle on the barrel as the problem. Things can happen coincidentally 
 
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This is why I get a significant amount of pucker factor at the mere thought of polishing or recrowning a barrel, especially on a gun that already shoots well enough and doesn't really "need" the modification. Not saying that was your situation, though. Hope it works out well for you.
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Agree totally. I tinker with almost everything but if a gun shoots well I won't touch the barrel or crown. Competition might require more risk but for most of us such work just seems too risky for me to attempt.
 
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For most things I'm very reticent to fix what ain't broken but I've gotten to where I end up working on every new barrel I touch. Granted I don't deal with a lot of premium stuff but I'll go after a Lothar Walther, for example. Doubt I'd touch one on a Daystate, for example, unless something was clearly amiss.

That includes polishing the bore but I always work from the breech end and apply progressively fewer strokes out toward the muzzle. I've had some stinkers that never would shoot well and occasionally one that doesn't improve but have yet to have one shoot worse for having tried.

Hopefully a good cleaning and reseasoning clears it up!
 
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Maybe try larger diameter pellets. You don't give a guy much to go on . Different brands and sizes.
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I tried different pellets after the JB paste and got very weird feedback. I normally shoot jsb 18.13gr, they shot accurately at 50 yds but with max power I only achieved 860 - 870 fps.

I decided to try polishing the barrel in the hope of getting a little more fps. I tried the .22 hades which flew at low 910's and the point of impact was 8 - 10" lower than the jsb 18's.

The H&N 14.66 was 10 - 12" higher than the POI of the jsb 18.
 
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For most things I'm very reticent to fix what ain't broken but I've gotten to where I end up working on every new barrel I touch. Granted I don't deal with a lot of premium stuff but I'll go after a Lothar Walther, for example. Doubt I'd touch one on a Daystate, for example, unless something was clearly amiss.

That includes polishing the bore but I always work from the breech end and apply progressively fewer strokes out toward the muzzle. I've had some stinkers that never would shoot well and occasionally one that doesn't improve but have yet to have one shoot worse for having tried.

Hopefully a good cleaning and reseasoning clears it up!
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Thanks!
 
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so you shot from a tin and it grouped good , then you wanted it better so you polished it now it wont group with same ammo ? if so , the crown must have a nick or blemish , paste wont enlarge barrel to lose accuracy ,, did you do it on a lathe? is the barrel tight and installed properly > what kind of gun is it ?
Click to expand...

I assume the JB treatment was done with a rod. If so, the "rodder" must exercise extreme care to not let the rod rub against the crown and/or the lands of the rifling at the breech end of the barrel. That JB stuff is a quite fine abrasive, but it can help damage a barrel if the rod rubs against those key contact points. This is especially true if the rod is a jointed one made of brass or aluminum. The joints, along with the soft metal, collect the abrasive so that it becomes an instrument of destruction. Bottom line: Don't let a jointed rod in the same building with a prized gun barrel.
Click to expand...

The crown is intact, but I think the lands and grooves might have been rubbed by the end of the rod.

Does anyone know where I can purchase a replacement barrel for a Kral puncher pro 500?
 
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hey dont buy barrel remove you moderator and shoot a few groups , and post them with and with out moderator , If you say crown is good , I assume you mean you put it on a lathe and barrel is square and straight ? hey shoot groups if you think it is barrel , I can put it on my lathe and spin it by eye a bad crown is almost impossible to see . but hatsan sells barrels



I have had square shrouds on my hatsan btg5 and it was all over as it clipped moderator ,

secondly polishing barrel wont boost power , if you want to boost power you need to change hst or weight or port sizes , as far as some shoot hi and some low sounds like you clipping
 
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