pellet spiraling

[Guest]

I'm shooting jsb 33.95 grain at 825 fps with no signs of clipping. I got a new barrel about a month ago because my first one had pitting but was very accurate. I thought this barrel was still "breaking in" because its not as accurate. Now I know why its not as accurate, but I don't know why the pellets are spiraling. Any help please?

 

[30cal]

Well it should not be over powering them at that speed so something must be damaging the pellets. Try pushing a pellet through the barrel with a rod or dowel then check it for damage carefully.

 

[Guest]

I'll try that in the A.M. Thanks 30cal

 

[Enkey]

Hi FastEddie
What airgun is? And barrel st lw cz bsa?
Tanks

 

[Guest]

Hey enkey. Its a wildcat with st barrel. I pushed a few pellets thru and although there was a lot of resistance at the breech where the brass meets the steel barrel they looked fine. I'm gonna go shoot some without the airstripper, moderator and endcap on.

 

[Dartagnan]

You may also want to inspect the crowning while you have it apart. How did you know it was spiraling, you have the slow-mo going?

 

[Antj]

Hey FastEddie,
Are you getting spiraling with just the 33g jsb's? Or are you seeing that with the 25.4g also? What batch of 33g are you shooting mkll?

 

[Guest]

Yes I just hooked up my new casio ex zr 1000 and Eagle vision scope cam adapter. I am using the mk2's. The spiraling wasn't as bad with the 25.4 kings but there was some. I just shot 4 pellets without the airstripper and endcap on with the mk2's and it was a big difference,very tight group, but 2 of the pellets still had a very minor spiral. So what does everyone think? Is there a problem in the breech area? Its very tight where the brass meets the steel, there's a groove that the skirt falls into and it takes some force to push it past that. What should I look for on the crown? This is my first pcp. Thanks everyone. Eddie

 

[Guest]

Before I noticed this spiraling I have been talking with ajshoots about polishing the bore. I ordered the supplies, should be here Wednesday. Some bore mops,bore rod and some jb bore paste. Maybe this will help? What do you think?

 

[Dartagnan]

I know you've been working on increasing the velocity to where you have it now. Wouldn't hurt to decrease the velocity a bit, say 800fps or less and see if there's a significant difference. The crown should look smooth and even all the way around. No burrs (you can check with a Q-tip and see if any fibers are snagged) Here's a picture i snagged on the net of a bad crown.
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. 

 

[Dartagnan]

Deleted echo!

 

[Guest]

I you zoom in the end of the barrel (crown) it doesn't look perfectly round. It almost looks hexagonal.

Or am I seeing things?

 

[Guest]

Thanks Dartagnan. I used a qtip and didn't see any burrs. My hammer spring adjuster is still frozen so I left it alone for now. Would the end of the barrel not being perfectly round (see picture above) have an effect ?

 

[30cal]

That's interesting. I know that ST barrels have the rifling applied from the outside which could explain that but I would still think the crown should be round.

 

[Dartagnan]

No matter how much I stare at it, that just doesn't seem right. I mean, I don't have the experience enough with FX to evaluate and give the right advice. This is something I would send to Johan and get his input. Meanwhile, do you still have the other barrel? Also, I am curious, I thought the end of the barrel has a threaded end for the shroud spacer.

 

[Guest]

It does. If you look at your barrel the last 2 1/2 inches unscrews leaving the " inner barrel" where they apply the smooth twist. Thanks again. I'll send that picture to Johan.

 

[Bwalton]

Is that the crown of a wildcat barrel? wow should look like this... I re-crown every barrel no matter what, could be the barrel, but 820 shooting heavies is way too low in my opinion, I would stick to the 25gr Kings

 

[Enkey]

Hi.
Yes the crown barrel is pentagonal is normal. The problem is in the copper probably. Diameter of copper is standar metric 6,5mm and barrel is 6,35mm (.250") of 6,5 to 6,35 is a burrs that damage the pellet, and the transfer port hole is probably have burrs. Check these two things.

 

[Guest]

Thanks enkey. Is there anyway to fix it?

 

[Dartagnan]

"Bwalton"Is that the crown of a wildcat barrel? wow should look like this... I re-crown every barrel no matter what, could be the barrel, but 820 shooting heavies is way too low in my opinion, I would stick to the 25gr Kings

Bwalton- What brand is that barrel in your picture? Nice work!