Opening up choke a little.

You should absolutely remove the barrel if you are planning to lap out bore material to increase the choke diameter. You'll be using some type of abrasives and oil lubrication to remove the material, and you do not want any of that stuff getting into other parts of the rifle or screwing up your bore.

If you're doing this to improve precision with slugs, then you shouldn't just try and "wing it" .. your chances of screwing uo the barrel are higher than not. As a general rule, the optimal groove / major inside) diameter is 0.0001-0.0003" under the projectile diameter. Therefore you should be taking precise measurements by "slugging" the choke and measuring with a micrometer that has high enough resolution.

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Could just order a longer barrel from a puncher mega and cut and crown the muzzle end. Going to be the cheapest and easiest route IMO. Then you'll have a slug barrel.

Yes, Krals have tight chokes and that's why they're very accurate with pellets. I've only found a couple slugs that they'll work with.
 
There are probably some very skilled machinists that could attempt this job, with no guarantee of success. And it would probably cost more than a new barrel. I believe that some pellet testing will indicate some pellets that shoot fine in your barrel. This is a very fundamental feature and not flexible. It's kind of like the feel of the way a particular car drives. You either like it, or, you give someone else that opportunity.
 
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Could just order a longer barrel from a puncher mega and cut and crown the muzzle end. Going to be the cheapest and easiest route IMO. Then you'll have a slug barrel.

Yes, Krals have tight chokes and that's why they're very accurate with pellets. I've only found a couple slugs that they'll work with.

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Keep the old barrel and replace it.







 
OK Folks I have completely forgotten about it. Far to difficult for me. As I said I am just hedging my bets because the gun arrives tomorrow. It's 12ft lbs. It's just that I have read several times that it has a tight choke. With a bit of luck it will be fine but knowing me I shall be comparing it to my hw 110 which is perhaps unfair. Thanks for the advise.
 
Pete -

When you get the gun...clean it, and...just shoot it !!!

Don't worry about what MIGHT be or what might NOT be. After you put a tin or two worth of pellets through it, if you have a problem, THEN worry about modifying things.
You may NOT have any problem at all.

Mike
Thanks Mike, I usually use white spirit for cleaning barrels. Not a great fan of barrel cleaning unless the accuracy starts to drop off.
 
Could just order a longer barrel from a puncher mega and cut and crown the muzzle end. Going to be the cheapest and easiest route IMO. Then you'll have a slug barrel.

Yes, Krals have tight chokes and that's why they're very accurate with pellets. I've only found a couple slugs that they'll work with.
I disagree on Kral being accurate with pellets.
My Akela .22 and Kral NP03 .22 and .177 are not accurate with most pellets.
Akela is gone now but I still struggle with shooting accurately the NP03s.

Maybe if I caved and spent 5 cents on JSB pellets (as recommended by some people here) I could get them to shoot accurately.
But I will not do that when my other PCPs (anything made by Nova Vista, Avenger, Nova Liberty/Freedom, Seneca Aspen, Beeman, Crosman, etc) have no problem shooting cheap Crosman pellets.

Choked barrels are an abomination.
I have so many airguns (just as cheap) which are more accurate with a variety of pellets than the Kral airguns.
So, the NP03s will be the last airguns with choked barrels I will ever buy.
 
The np03 has a horrible spring from the factory and cliff dives on its shot string which makes the accuracy suck. The small reservoir doesn't help. I usually change out the spring with a heavy/shorter one and up my pressure to 230-250 bar. Tightens up the groups, and gives better power/consistency/and shot count.

My 177 np03/mega rifle was lights out to 50 yards with cheap cphp from Walmart. Probably killed 200 sparrows last year with that combo, and most were head shots. My 22s are also very accurate with multiple pellets, better than the 177s for sure. Best groups I get are from my 25s. One is an np01 barrel and the other is np03 and they both will stack pellets.

Sucks you're having crap luck with it. My Krals prefer a diet of H&N though, Jsb are so so.
 
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