Currently, I'm thinking that is just coincidence.
Via your measurements, the rounds with heavy bolt lift are .002" longer than the ones without. Your loaded round is falling free, so you're likely not running into pressure from a carbon ring. Especially after only a few rounds since last cleaning.
If your fired brass that was heavy lift functions properly after sizing and firing again.....then I wouldn't worry about getting wrapped around why those rounds were growing longer. Especially since you've checked headspace with go/no go.
If they do stick again, get some more virgin brass of a different lot number and see if the problem repeats. As with the measurements you provided, there doesn't seem to be any obvious reason for pressure.
There is NO lead in the bore or throat. The bullets you are using have a solid base not open to show lead. That would be the only way to get lead in a bore from a jacketed bullet.
The carbon you are seeing is more of a burn mark NOT a carbon build up. YET. What you have in the chamber is a non issue.
New brass just seems to do this every once in a while. Just make sure to not go under a 10% or so reduction in powder from a max listed load. That will also give you pressure signs from erratic ignition. You also might want to use a different primer. The ones you are using might be a little hotter than other types.
The carbon you are seeing is more of a burn mark NOT a carbon build up. YET. What you have in the chamber is a non issue.
New brass just seems to do this every once in a while. Just make sure to not go under a 10% or so reduction in powder from a max listed load. That will also give you pressure signs from erratic ignition. You also might want to use a different primer. The ones you are using might be a little hotter than other types.
1. Clean that barrel to bare metal with thorroclean, JB worst case Iosso. Scope it and make sure all the black carbon is gone from the throat area. Next run a patch with alcohol through the chamber and barrel then go shoot.
2. Try shooting with the ejector spring removed but the ejector in place. Any debris in the ejector hole? Can you push the ejector down below the face of the bolt? The part with the red is showing that the brass is flowing into the ejector hole or there could be a burr catching the brass. The opposite side of the bolt face shows more brass markings which could mean the ejector spring is pushing the case hard. Try a lighter ejector spring. Erniethegunsmith sells the lighter springs, flings the brass out just not 3' away.
After removing the ejector run the tip of a paper clip across and around the ejector hole, do you feel any burrs?
Another issue could be the chamber is too smooth to grip the brass upon firing causing bolt thrust. A simple test would be to scuff up the brass body only with a green scotch bright pad and see what happens.
Reloads:
Bump that shoulder back .002-.003 from touch. The case needs room to expand and contract. Not all brass is consistent some grow faster than others all within the same batch. Someone mentioned this above.
Make sure cases are free of everything, wipe down with alcohol, if you dry tumble wipe all the dust off.
2. Try shooting with the ejector spring removed but the ejector in place. Any debris in the ejector hole? Can you push the ejector down below the face of the bolt? The part with the red is showing that the brass is flowing into the ejector hole or there could be a burr catching the brass. The opposite side of the bolt face shows more brass markings which could mean the ejector spring is pushing the case hard. Try a lighter ejector spring. Erniethegunsmith sells the lighter springs, flings the brass out just not 3' away.
After removing the ejector run the tip of a paper clip across and around the ejector hole, do you feel any burrs?
Another issue could be the chamber is too smooth to grip the brass upon firing causing bolt thrust. A simple test would be to scuff up the brass body only with a green scotch bright pad and see what happens.
Reloads:
Bump that shoulder back .002-.003 from touch. The case needs room to expand and contract. Not all brass is consistent some grow faster than others all within the same batch. Someone mentioned this above.
Make sure cases are free of everything, wipe down with alcohol, if you dry tumble wipe all the dust off.
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How come no one recomended to shoot over a chrony? High pressure will also show as higher than normal velocity. Then you should see if the heavy-bolt-lift brass are actually overpressure or not.
Apart from the "mild powder charge" all other indicators point to overpressure rounds.
Apart from the "mild powder charge" all other indicators point to overpressure rounds.
The case is wedged in the chamber afterwards.
The difference is that the person wedged it into the chamber in the first place, not that it expanded too much at the trigger pull.
Yeah, kinda, but expands and wedges even further when fired. I had heavy bolt lift. I think I may have had ejector swipes too but I don't recall for sure. But the bolt was harder than hell to lift with what I know is not an overpressure load. Dumped the neck die, got a Type S FL bushing die, bumped shoulders 2-3 thou, problem solved. (That die resizes the body too, of course.) Cases were not hard to chamber, just to extract. According to that Brian ballistics guy that was a guest on the Hornady podcast, lube in the chamber can cause massive pressure spikes too, and back at that time I was not properly de-lubing my cases, which probably contributed to it too.
I dont recall seeing a case stuck in the chamber as such have ejector marks or heavey bolt lift unless there was hard bolt close.
Sent you a PM. I have the same issue with a 6.5 creed Bart spun for a Zeus QC. I’m running alpha brass however. Inconsistent pressure after 30 shots or so. Hard bolt lifts and ejector marks.
Edit:
I have run both federal, and Winchester factory ammo through the rifle and did not get any pressure signs. I’m shooting
129 SST
41.5 grn of H4350
Alpha Brass chamfered and deburred
.262 21st century mandrel
Pressure signs popped up and I deep cleaned and scrubbed the bore. Ran another 50 through with no pressure signs.
Average velocity
2777 over 25 shots
2797 over 15 shots
The 2 groups were shot on 2 different range days. 15 degree temp difference on the days the groups were shot.
Edit:
I have run both federal, and Winchester factory ammo through the rifle and did not get any pressure signs. I’m shooting
129 SST
41.5 grn of H4350
Alpha Brass chamfered and deburred
.262 21st century mandrel
Pressure signs popped up and I deep cleaned and scrubbed the bore. Ran another 50 through with no pressure signs.
Average velocity
2777 over 25 shots
2797 over 15 shots
The 2 groups were shot on 2 different range days. 15 degree temp difference on the days the groups were shot.
Attachments
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I keep this link handy, good video of what you have explained.
Videos | wheeleraccuracy
www.wheeleraccuracy.com
I skimmed through this thread so maybe I missed something but it appears you’re running .003” neck diameter clearance. I think that’s the problem. Try something with a thinner neck or turn your lapua necks.
When I had that much clearance in my 22-250 I had those problems. Increasing clearance made the problem go away.
It started out immediately. I had to back off the load to the point I was 200 fps under what I wanted and had to scrap the whole thing. Tight neck clearance is stupid.
What's stupid is applying an absolute across the board for one instance. Why does it work in 7mm and not your 22-250? So, I take it you weren't able to slip a bullet into a fired case? With 3 thou clearance I can slip a bullet in my fired cases. They ride in without much wobble.
It’s not enough that the bullet slip through a fired case. It’s not that. It’s a start pressure issue I think.
Did you try using the brass from the factory ammo you ran without problems? Is the neck clearance with that brass bigger?
Compare the factory brass dimensions to your alpha brass. I think you’ll find the clearances and internal volume will be bigger.
What I’m noticing is that your “problem” cases didn’t expand at the .200” line. They over expanded in length causing bolt thrust. I’m aware of something similar happening a few years ago with a different cartridge that was caused by brass being too hard. The issue in this situation was solved by firing the cases a few times until they expanded to grip the chamber.
I don’t believe your loads are over pressure or that you have a fouling issue. I think you are having an issue with certain brass fire forming to your chamber. I’d follow the advice of Rio Precision and bump your necks back .002-.004” less than touch on close. I’m betting the issue will resolve itself in a few firings of the brass. I’d be willing to bet you could even run the same brass at higher pressure without seeing the same signs.
After
Scope the chamber after 50 rounds to see if there is significant carbon build up in the throat.
Seems to be the carbon build up if after 50 rounds the pressure appears.
Scope the chamber after 50 rounds to see if there is significant carbon build up in the throat.
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