AI AT won't extract live round with new barrel?

Slu54

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Minuteman
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Apr 28, 2007
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Pittsburgh, PA
Hello:

I've just put on a new pre-fit barrel from a Proof blank on an AI AT. 6mm Creed. I haven't had a chance to shoot it yet but I've noticed it can't extract a live round. I don't have a 6mm case to test but it extracted the headspace gauges just fine.

Before this I had a Bartlein 6.5mm Creed barrel from Mile High, extraction was always good live or just case. I spun it back on just to check, extraction still good with the old barrel.

Just comparing by hand with the barrels off the action, does take a bit more effort to get a round out of the new barrel versus old.

Will this go away as I shoot it? Or barrel problem? Or extractor problem? Let me know if you've experienced similar. Even if it extracts spent cases fine it sure will be annoying if I can't extract live rounds.

On headspace, it closes on a PTG go gauge, but will not close on that +6 thousandths.
 
So you close the bolt on a live round and when open it, the bullet stays in the chamber?

When you get the bullet out finally are there land marks deep into the bullet?
 
So you close the bolt on a live round and when open it, the bullet stays in the chamber?

Yes, except the whole cartridge stays in there.

When you get the bullet out finally are there land marks deep into the bullet?

Not that I can tell. Because the AI is 6 lug the chamber is pretty deep in there I can't pry the round out from the breech end, so I had to tap it out with a cleaning rod from muzzle end. It takes a tap to get it out, but not really a great amount of force.

The new barrel does have a bit more headspace than the old one. Old one closed on go but did not on no-go. No-go is 0.003" longer than go. This new one closes on go, closes on no-go, but does not close on no-go plus one layer of tape, which adds 0.003". So new barrel has somewhere between 0.003" and 0.006" more headspace. Does 6 thousandths really make or break extraction?
 
Is this a reload or a factory round your testing? If your headspace is as much as you say which isn’t a big deal and you’re using a new factory round, you likely have variance in the neck diameter on the reamer used, short throat or body diameter issue at the web area from worn reamer or such.

If it’s a reload start over with a new piece of brass and see what you get
 
The new barrel does have a bit more headspace than the old one. Old one closed on go but did not on no-go. No-go is 0.003" longer than go. This new one closes on go, closes on no-go, but does not close on no-go plus one layer of tape, which adds 0.003". So new barrel has somewhere between 0.003" and 0.006" more headspace. Does 6 thousandths really make or break extraction?

Depends on how far off the headspace of the round you're chambering is. If it's already 7-10 thou (maybe more) short of saami spec, and your chamber is 4-6 thou deeper than saami, it could be enough that your extractor isn't getting all the way around the case head.

Only wrinkle would be that the rifle apparently still fires, you'd think you would be seeing light primer strikes if it was that far off headspace.
 
Headspace would have to be grossly excessive to not allow the extractor to grip the case rim.

It’s a 6mmCMoor chamber and extracts a HS gauge fine? Is it a 6mmCMoor round that it is failing to extract?