mossberg 500 extractor issue

Couldve gone in the shotgun section i suppose but this probably gets more coverage.
In anticipation of the upcoming duck shooting, got the 500 out to have a proper look at an annoying problem it has had for a long time.
I was in aussie for 10 years so that added up a bit.
When it has had a few rounds put through it in quick succession, like half a packet in 5-10 minutes, fired cases start to stick and are a bitch to get out.
Some good lubrication of the chamber and a cool-down helps but finally decided to have a bit of a squiz.
There are threads on sticky chambers needing a polish etc but wanted to get the tele gauges and micrometer out and at worst make a dummy out of steel to look for any silly high spots.
But first things first was to look at the extractors. Look alright I suppose, although I do realise even a small rounding can have an influence.
Sliding a case onto the bolt face (out of the gun) and it seems to do what it should. Grabs quite tight and the left-hand side is rounded to let it spit out the chamber when it hits the extractor
But the next thing I tried was to put a shell in the chamber of the barrel (also out of the gun) and just trying the "bolt to case to extractor slot" fit.
This is where it gets interesting. with the bolt pushed hard up against the shell in the chamber, the extractors are forced back away from the case just a little.
You have to push the bolt home against the extractor spring tension.
This pushes the extractors out from the rim and to my mind reduces the pulling power of the extractors by quite a lot especially if the rim of the case is a bit tapered like some of them are. There is the odd note online about making sure the extractors fit properly on the bolt and arent held out so this seems to be doing the same thing
I may still have an issue with the chamber but first things first.
Can anyone have a look at theirs and see if they are the same?
Can the extractor slots on the barrel be eased back so the extractors are fully seated when the bolt is in battery?
Cheers

I have 2 barrels for mine which could be checked in yours as I suspect it may be where it meets the barrel

From Mr Google.....
My older Mossberg 500a was not always extracting 100%, I took it to a good gunsmith, he told me that the 500 pumps can have this problem, and it is a "design" flaw.
It was is not the extractors, but the small cuts in the barrel where the extractors fit into.
The left side extractor was rounded off a bit due to the tight extractor grooves in the barrel.
The gunsmith milled out the extractor grooves in the barrel and touched up the left extractor and problem solved.
No more fail to extract.

Might have to take you up on that Ted.
Strangely though that is the exact same and only reference to that I found lol
With the gun all back together it is very noticeable that the extractors are pushed apart as the bolt goes to battery in the last 2mm

@gundoc what are your thoughts on this?

A combination of opening out the barrel grooves, and very minor reduction of the leading edges of the claws should cure it. Make sure that the extractor claw has a sharp edge. Any rounding of the edge will cause it to slip on some ammo, particularly the cheaper types where the gases can bypass the base wad and expand the rims slightly.

@gundoc cheers was going to do the most on the barrel if that was acceptable
Yup seen on the old 22 how bugger all difference on an extractor can make between empty cases coming out and not
As a side note found out the mate who comes down from the north island for opening is too busy to come down this year. It was already a bit of a mish to head over and wasnt sure if I could be bothered
Now he isnt going not sure if I can be naffed so probably dont need it