I have a proof ss 6.5cm zermatt origin action prefit barrel and I noticed that after firing my case necks are still tight enough that a bullet doesn't go in easily. Is that normal? They bull will slide in but it's like there still a bit of neck tension like the area in my chamber where the necks are is small enough that the necks don't expand very much at all. Obviously you don't want them to blow out a ton but it is normal to have the necks still pretty tight even after firing?
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Brass neck after firing
- Thread starter JRBullock1987
- Start date
If you take a bullet, position it in the mouth of a fired case, and let go.... does it drop all the way down into the case? Or does it hang up, somewhere around the shoulder/neck junction of the case?
I have to force into into the case mouth it doesnt drop freely at all. I can move it in and out of the mouth but it takes force to do it. It's not as snug as if it were sized but it's tight.
Okay, back up. Is the main diameter of the bullet (bearing surface) entering the case neck freely at all? Is it hanging up right at the mouth, or down towards the bottom of the neck?
Agreed, particularly with the 30 degree shoulder, and I'm guessing not that many firings. But if he's not wet tumbling, peening of the mouth is a bit unlikely as well.
If the neck OD is what he says it is, something is making the neck ID smaller than it should be. I'm just trying to narrow down *where* in the neck the narrowing is, so we can definitively rule out one or the other. And unlikely as either of those may be, there's not a lot of *other* likely suspects.
Should be interesting!
On a couple pieces of brass i shot today which have 2 firings i can get the bullet to slide in and out with a little bit of effort but it slid fairly free but on some others I couldn't force it into it unless I tried hard. It's not just from the shoulder either it's the whole neck being tight. Here's a pic of a hornady 140gr eld match sitting on top like its been resized.
Does the Orgin have spring powered or mechical ejector? Spring powered ejectors tend to run the mouth of the case down the inside of the action and make a flat spot. This also makes bullets not quite just drop into the case.
Is the case mouth visibly round / concentric? Any dents or dings, however slight? Like from ejecting out against a barricade, or onto a concrete bench at the range. Or ejecting onto a bench, and falling onto the concrete deck. Any or all of those can result in a case mouth that is out of round.
If they aren't visibly dented... on the cases that the bullet just sits on top of, can you see or feel any kind of lip or burr on the inside of the mouth
No they are the same. Even on the ones that the bullet goes into it's pretty tight. I have to coax it in
I had this issue when I was wet tumbling with pins for a long time. It peened the mouths so they were thicker at the mouth. I ended up using a Wilson inside neck reamer to clear them out and uniform the neck thickness all the way down the neck. Obviously you said you're not wet tumbling so this shouldn't be the case. And I don't think this happens when dry tumbling but it sounds like you have varying neck thicknesses if they all measure the same but the fit is different. If you have a ball mic, you could measure the neck thickness in the front of the case mouth and then deeper towards the neck shoulder junction and see if you can distinguish some sort of meaningful difference to begin to shed some light on the issue. So far, everyone is goose eggs on what the problem is. If you don't find anything with a ball mic, you might just need to go off how it shoots. If the fired necks are still 3 - 4 thou larger than sized/ loaded and it shoots tight groups 
Well I shot a .274 4 shot group when zeroing a new scope yesterday with a random load. First shot was low. I corrected and shot a 4 shot group with the remaining 4 rds of the load. Amd it's went into the .274 so I thinks it's gunna be a really go9d shooter. It hasn't been 100 percent broken in yet. Only has 50 rounds on it.
I anneal every time. It's hormady ammo, and I usually use alpha munitions, so im not sure if alpha will be thinner or thicker. Do you know if alphas thinner than hornady ammo typically?
You never answered the other half of my question:
If they aren't visibly dented... on the cases that the bullet just sits on top of, can you see or feel any kind of lip or burr on the inside of the mouth? Maybe with a pick?
Also, something else that would be interesting to know... how thick are the necks, actually? Even if you don't have a ball micrometer, you should be able to get a close-ish value using your calipers. For that matter, try using the back side of the calipers to measure the inside diameter of the necks.
Something isn't adding up here.
If they aren't visibly dented... on the cases that the bullet just sits on top of, can you see or feel any kind of lip or burr on the inside of the mouth? Maybe with a pick?
Also, something else that would be interesting to know... how thick are the necks, actually? Even if you don't have a ball micrometer, you should be able to get a close-ish value using your calipers. For that matter, try using the back side of the calipers to measure the inside diameter of the necks.
Something isn't adding up here.
If it makes you feel any better, I have the exact same thing going on with a 6BR. Virgin Peterson brass, once fired won't take a bullet without some force. Measures .266 after sizing with a Redding Type S .266 bushing, .269 loaded, .271 fired. Neck thickness with a Mitituyo ball mic is very consistent between .0130 and .0132'ish 3'ish. Shoots fantastic, no pressure, low SDs. Zermatt TL3 and Bartlein chambered by Keystone. Brass has never been tumbled. Uniform neck thickness all the way round and up and down the neck. It's just spring back as far as I can tell and based on the way it shoots I don't really care to make it a big science project. I'll see how it looks after annealing it on an AMP.
And you're shooting Hornady brass. I definitely wouldn't invest a lot of time and energy into that stuff.
And you're shooting Hornady brass. I definitely wouldn't invest a lot of time and energy into that stuff.
I don't know if Alpha is thicker in the necks, I take it you have Alpha in other cartridges, or you would be able to test yourself?
Yeah, I wouldn't be polishing a turd with the Hornady brass.
I would also contact whoever chambered it and see if they can tell you the dimension of the case neck area. (From the reamer print)
Yeah, I wouldn't be polishing a turd with the Hornady brass.
I would also contact whoever chambered it and see if they can tell you the dimension of the case neck area. (From the reamer print)
I have alpha brass for 6.5cm i just don't have the ability to load any right now bc my scale is getting fixed at rcbs
Well, clip your calipers on the inside of the neck and get a measurement. Compare this to the Hornady. You will be within .0005 with calipers. I know the ball mic is the textbook tool, but calipers get it done to that .0005.
How are you trimming? What device, and how are you chamfering/deburring?
I ask because, some trimmers, like Hornady, RCBS, and Redding can deform your neck if you press in too hard. Honestly, I don't really think you have an issue. A dozen things could be happening: spring back, eccentric case mouth, issues with the expander ball or button, deformation of the case mouth during tumbling... etc.
The point is for the bullet to come out. I don't see why you feel the case should accept a bullet after firing. I've never heard of that being a check. Frankly, I've never checked. How does it shoot?
I ask because, some trimmers, like Hornady, RCBS, and Redding can deform your neck if you press in too hard. Honestly, I don't really think you have an issue. A dozen things could be happening: spring back, eccentric case mouth, issues with the expander ball or button, deformation of the case mouth during tumbling... etc.
The point is for the bullet to come out. I don't see why you feel the case should accept a bullet after firing. I've never heard of that being a check. Frankly, I've never checked. How does it shoot?
So coincidental then he hit the usual neck thickness... Lets say I don't know. It becomes a relative measurement then. He turns .001 off his brass and now he has a bullet slip through and clearance. So he uses that new caliper read and then checks the OD of the case neck with a loaded round.
My 7mm I have to turn necks. I know if the caliper clip reads .0135 my OD of loaded case neck is .312. and measured by micrometer. My chamber is .316. When the caliper clip reads more or less, then so does that loaded bullet OD. Between my caliper and my micrometer I have a .0005 tolerance difference. I can certainly live with that.
My 7mm I have to turn necks. I know if the caliper clip reads .0135 my OD of loaded case neck is .312. and measured by micrometer. My chamber is .316. When the caliper clip reads more or less, then so does that loaded bullet OD. Between my caliper and my micrometer I have a .0005 tolerance difference. I can certainly live with that.
I use the l.e. wilson trimmer so the ID of the neck doesn't get mangled from the pilot on other trimmers like redding. And I use a an rcbs vld chamfer (ID) and le wilson deburr (OD). Hopefully I got those labels correct. I always get them backwards. I was planning on sending in a piece to hornady to have them make a custom coal modified piece of brass and when I tried putting in a bullet I had difficulty so I tried several with the same outcome. Which led to my question. I remember my .223/5.56 fired brass neck opened up wide enough for bullets to fall in really easily so that got me wondering if something was wrong
