SK ammo question

[MtnMan]

just cleaned the bolt under the extractor, the chamber and bore and lightly oiled the chamber. Now it ejects live SK but not fired SK. Also won't eject live Win super suppressed all of a sudden. really starting to piss me off now. I'm starting to suspect that on closing the bolt that the extractor is wedged away from the case by the contact with the breech face.

[MtnMan]

I'm suspecting that the extractor is hitting this angled face of the breech and being pushed away from the case rim. I'm thinking that the slightest touch from a dremel to create the smallest of recesses for the point of the extractor hook to sit into, so that it can move closer to the centerline of the bore and engage on the case rim. I think the extractor hook can't get in right behind the rim. variance in case rim thickness or diameter will exacerbate the problem I'm experiencing.

you can see here at the end of the pointer where I think a recess should be made to allow better extractor engagement on the case rim.
It actually looks like a small ridge at the edge of the chamber like that face hasn't been milled completely flat.
What say you?

IMG_8276.JPG (24.07 KiB) Viewed 3190 times

[bladeracer]

just cleaned the bolt under the extractor, the chamber and bore and lightly oiled the chamber. Now it ejects live SK but not fired SK. Also won't eject live Win super suppressed all of a sudden. really starting to piss me off now. I'm starting to suspect that on closing the bolt that the extractor is wedged away from the case by the contact with the breech face.

I'm suspecting that the extractor is hitting this angled face of the breech and being pushed away from the case rim. I'm thinking that the slightest touch from a dremel to create the smallest of recesses for the point of the extractor hook to sit into, so that it can move closer to the centerline of the bore and engage on the case rim. I think the extractor hook can't get in right behind the rim. variance in case rim thickness or diameter will exacerbate the problem I'm experiencing.

you can see here at the end of the pointer where I think a recess should be made to allow better extractor engagement on the case rim.
It actually looks like a small ridge at the edge of the chamber like that face hasn't been milled completely flat.
What say you?

IMG_8276.JPG

If it was working fine before it seems unlikely these angles and clearances could change.
Have you cleaned out the extractor recess?
My JW21 tends to shave lead off the bullets and that debris can fill up the recess causing extraction issues if I don't keep it clean. It's the only rifle I have that needs cleaning every 300rds to keep it running because of the debris that gets into the action. I use dental picks dipped in grease.

[MtnMan]

yes all that has been cleaned

[bladeracer]

yes all that has been cleaned

And it's only an issue with SK PMS?
Certainly very strange.
How many rounds has the rifle fired?
It might be worth grabbing a new extractor and spring and see if they fix it. Doesn't hurt to keep spares on hand.

[MtnMan]

now seems to be ejecting live SK PMS where as before it wasn't. also now has trouble with the odd live Win super suppressed that up until now hasn't given trouble.

first It was just the SK now it seems to be all over the place. It just seems like the extractor point isn't able to get in behind the case rim to hook the case out.

[MtnMan]

Well I took a Dremel to the breech face to create a relief enough to accommodate the extractor which helped because it was hitting the breech face and being wedged away from the rim. I guess that's a function of head spacing. Now it can sit in and engage the rim positively.

The thing that got it working was lubing the chamber and cartridges with case lube. This got the SK PMS going from 0% extraction of fired rounds to 100% extraction of fired rounds.

It fixed the Win super suppressed that was playing up too.

[Wm.Traynor]

Lubing the chamber and cases horrifies me.
However, I am speaking from the perspective of a centrefire owner. It is verboten where centrefires are concerned. I hope your rifle is OK

[bladeracer]

Well I took a Dremel to the breech face to create a relief enough to accommodate the extractor which helped because it was hitting the breech face and being wedged away from the rim. I guess that's a function of head spacing. Now it can sit in and engage the rim positively.

The thing that got it working was lubing the chamber and cartridges with case lube. This got the SK PMS going from 0% extraction of fired rounds to 100% extraction of fired rounds.

It fixed the Win super suppressed that was playing up too.

Be sure to wear safety glasses when you test fire it after taking metal out of the extractor recess. That metal supports the case pressure, if it fails the case will rupture and vent the gas back toward you.

Lubing the brass sounds like a bandaid fix, find out what is causing the cases to stick in the chamber and fix that.

[bladeracer]

Lubing the chamber and cases horrifies me.
However, I am speaking from the perspective of a centrefire owner. It is verboten where centrefires are concerned. I hope your rifle is OK

Absolutely, very dangerous in firearms not designed for lubed ammunition.

[MtnMan]

shoots just fine. even high velocity stuff.

[Wm.Traynor]

shoots just fine. even high velocity stuff.

Accuracy is Not what I was getting at.
But getting back to centrefires for a moment..........................
A lubed case or one wet with water (rain), does not "grip" the chamber walls, as in the example of a dry case. Therefore, all of the backthrust is delivered to the locking lugs and their abutments, instead of only part of the pressure. The lugs etc., are not designed for this. Sooner or later, something will give.
I assume that applies to rimfires too.

[bladeracer]

shoots just fine. even high velocity stuff.

Accuracy is Not what I was getting at.
But getting back to centrefires for a moment..........................
A lubed case or one wet with water (rain), does not "grip" the chamber walls, as in the example of a dry case. Therefore, all of the backthrust is delivered to the locking lugs and their abutments, instead of only part of the pressure. The lugs etc., are not designed for this. Sooner or later, something will give.
I assume that applies to rimfires too.

Yes, it applies to rimfires as well. The pressures are lower than most centrefires, but much higher than shotguns. The problem with lubing the case is the bolt thrust can easily exceed what the firearm is designed to withstand. A .22LR operates at a maximum of 24,000psi, even hyper-velocity stuff like Stingers, but most ammo never goes that high. A .22LR might see 1000lb of bolt thrust, but lubing the case might make it 2000lb, or 5000lb, or much higher still, which could be more than the action is designed to take, at least full-time. A few rounds might have no longterm effect on it, a few hundred might start fatiguing the steel.

I've never heard of wet brass being an issue though, I may have to investigate that further. Water is a very poor lubricant so I doubt it gives.much variance in bolt thrust, but it might.

It's better to determine why the firearm has an extraction issue and address that directly, in my opinion.

[Wm.Traynor]

bladeracer
Any Fullbore shooter will tell you to keep your ammo dry if it rains, as wet ammo has a disastrous effect on elevation. Might be more important to a marksman at 300 yards than it is to a pig shooter at 100.
I recall making an elaborate cover for the action which extended past the nose of the comb, to keep the bolt dry when it was pulled back for loading and ejecting. If the bolt got wet it transferred water to inside the action. Where a round was dropped in, through the loading port, on the bottom of the action, was where water collected, from the wet bolt.
It made shooting a bitch, as if it wasn't hard enough already.
Please pardon the rave.