Strange marks on rim, rounds hard to chamber?

Having some trouble with a 7mm-08, will try to be brief.

New WW brass, weight sorted, trimmed and chamfered, loaded with a well under max load, fired. No problems at all.

Now lets say we take 50 fired cases, neck sized, trim, chamfer and clean. Headspace matches on all rounds, measurements from any point of the case all match up- nothing looks amiss. Sized rounds chamber easily, no stiff bolt or anything.

Except for a few. I don't have an actual count but lets say 4-5 empty cases will chamber "hard". It could be that it takes just a little more pressure than normal to close the bolt, or it can be very very stiff.

When examined the cases that chambered hard will have a dent on the rim, very narrow, and perpendicular to the case body, at a 45-60 degree angle that leaves a tiny bulge, or ridge on the front of the rim. Sorry I don't have a picture yet but imagine that the case were made of wax, and you took a needle and you tapped the side of the rim while slightly drawing it toward the case mouth.

My only guess is that the mark is made from the extractor but the dent is much more narrow than the extractor is wide and the extractor is clean, no signs of damage or debris. Also, there are tiny little brass shavings in the chamber sometimes after a hard extraction.

Thoughts?

Pictures?

http://i877.photobucket.com/albums/a...psae6255da.jpg

http://i877.photobucket.com/albums/a...ps0d3795fe.jpg

Not perfect but you get the idea.

Maybe they're damaged from the factory? Are you sure this is happening from your rifle?

Pull the bolt & place the bad case in the end of the bolt. See if you can determine what did it. Use a small light to look in the chamber & see if it's something in there.
To me, that looks like something hit it or it got hung up in something while it was dragged thru it - Possibly during mfg?....
Damage in transport?.....
I've never seen anything like that come from the inside of a rifle chamber UNLESS... there's something loose & floating around in there that you're not seeing. Especially if it's only happening to a few cases & not all cases.

Keep up posted unless someone here comes up with the actual answer to the mystery. Now I'm losing sleep over it. I need to know...

Thanks for the reply.

I've scoped the chamber and it is clean, the bolt body is as well.

Definitely happening in the chamber, some rounds go in clean,and come out clean, others chamber hard and come out with the dent.

Using a Lee collet neck sizer and then a body die to bump the shoulder. Works great for 98% of rounds regardless of how many firings, just a couple have this happen.

I draw blank on this one...
Wait until some of our more seasoned Savage Diagnosticians come to life this morning. I'm sure one of them will pick up on it.

I've observed some weird & sometimes unexplainable stuff over the years but this one has my interest.

Guys?.... Brethren of the Barrel Nut? - this man needs your help. I'm curious, too.

Im guessing the extractor claw is hanging up

Quote:

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Originally Posted by limige

Im guessing the extractor claw is hanging up

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Ya know, now that you mention it....
I suggested he pull the bolt & check it. Might be a real good idea to pop an empty case head in the bolt & manipulate the extractor a few million times to see if it is hanging up. Or - go the long route & just pull it apart. it's not that tricky to take it down....

Quote:

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Originally Posted by limige

Im guessing the extractor claw is hanging up

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That's my guess too. The rim is outside the chamber .125"( give or take a bit) so the only thing left would be the extractor or the ejector.

Bill

Disregarding to possibility of it happening outside of the chamber, I believe you guys are on to something. Guess we'll see what the OP says & does about it.

Funny thing though, sometimes the simplest solution just zips right by me. I looked right past what y'all looked right at.
Yet, another senior moment....

I'm trying to understand the hard chambering part. Either the brass is just simply fitting the chamber tighter, or the neck/body is offcenter (because the chamber was not cut concentric to the bore) so when you go to re-chamber the fired brass the rotation of the cartridge may not match the orientation when it was fired and the neck offset may now go the other way. This would certainly cause hard chambering.

Another possibility is that the extractor is not wanting to slide over the rim of the cartridge. Perhaps the machining is a bit rough.

Or perhaps the cartridge is chambering tight due to an off center neck and when you go to extract it the side of the extractor makes a gouge in it as the load is put on it by the primary extraction cam.

Anyway, sure is a bit of a mystery but the dent suggests that the extractor is not sliding smoothly over the rebate. It should not be too difficult to check whether the necks run true to the cartridge centerline after firing.

Great replies, thanks.

I took the extractor out, looked at it, the ball and spring. Everything looks and moves smoothly. The ejector was removed aeons ago.

As far as the bore being off center- the rounds that chamber hard will chamber hard when turned in the chamber and re-seated. The rounds that chamber easily will chamber easily when spun in the chamber and re-seated.

The thing that keeps hanging me up is that some rounds do it, and some don't. If it were an out of round chamber, or an extractor hanging up, wouldn't it be more consistent?

Do you get the same problem when you remove the extractor and chamber a large number of rounds?

You haven't per chance replaced the extractor with one for a .378" cartridge ( 223-204) have you?

The base of that cartridge looks pretty shiny. Did you EVER FL resize that brass ? I ask that because I just processed 500 never fired LC 308 cases that had the bullets pulled. Apparently Lake City thought they were OK but the military didn't think so.

One of the things I did was a full length resize and the base of some of the cartridges was substantially larger than others. Given the effort it took to resize those ones, I have to imaging that if you had a good, tight chamber, some of those might chamber very tight indeed. Then it is possible that the dent got put in the rim when trying to extract them. After firing they will be harder to extract than going in, since the front of the case and neck is fireformed to the chamber and will drag where it did not when you first chambered it.

If your cam on the lugs is good, it is a potent force multiplier and when you chamber you apply the force on the entire base of the shell. Whereas when you extract, the only place you pull on it is where the extractor is. So there is a big load concentration when you try to get a stuck cartridge out.

I suggest you put all the tight shells through your full length or body sizing die and make sure you go all the way up until the shell holder touches the die, since otherwise you won't knock down the base of the cartridge. Then see how it works for you.

If I buy new brass now, and if one can buy a body die for the caliber, I run the all of the brass through the body die to make sure I have no surprises, then neck size with my Lee collet die and I'm ready to go (assuming the length is good and doesn't need trimming). If there is no body die available, then it goes through the FL sizing die.

All cases have been through a body die, neck sized with a Lee collet die and trimmed.

You did that before you fired it or before you tried chambering it and it stuck ? Have you tried them in the body die since you know they stick ? Do you touch the shell holder to the die when you size ?

The only thing that the body die will not replicate is the fit of the neck in the chamber. If the brass is long you may be crimping the bullet. But you say you trimmed...

I am concerned that you think you did all that stuff but somehow you missed something. If it chambers hard now, it should fit tight in your body die. If not, then the body die is out of spec.

Quote:

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Originally Posted by BillPa

You haven't per chance replaced the extractor with one for a .378" cartridge ( 223-204) have you?

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Bill's right... you have the wrong extractor. The extractors for .223 and .204 are longer and will extend to the receiver wall and bottom out before it can clear the rim. Trim the outside edge of the extractor or get the right one.

I'll check that out but wouldn't that show up on all cases?

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Originally Posted by mattri

I'll check that out but wouldn't that show up on all cases?

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Not necessarily. It all depends on the rim diameter of the stick of brass being used. For example if the rim measures .464" it may be just enough to allow the extractor to ride over the rim without the tail end of it bottoming out in the lug recess while another stick with a .466" or more may not. Looking at your pictures its clear one is gouged more than the other. If you measure both rims the one with the deeper gouge will probably be a few thousandths larger in diameter than the other.

Its easy to check. While inserting a piece of brass in the bolt face watch to see if the tail end of the extractor protrudes past the locking lug as it rides over the rim. If does just shorten it .010"-.020" with a file.

Bill

Swapped the extractor- will post how it does. Thanks to all for the replies.