223 hard chambering question

[fkimble@charter.net]

Reply. Clean the throat real good with JB or something similar. Sounds like a carbon ring build up.

Frank

 

[DLT]

Probably a donut that gets pushed to the outside of the case when you seat the bullet. Probably 30% of my 223 Lapua brass forms a donut within 5 firings of new.

I can pick the small bulge up barely with my eyes at the neck shoulder junction with a seated bullet. However calipers and mics at work show a different story. My necks measure .250 halfway up between the shoulder and mouth, but closer to the shoulder I’m getting +/- .256 as the doughnut isn’t giving me a good datum line to get a solid measurement ( the neck/shoulder junction) kinda gets lost. Makes sense to me it’s back towards the rear of the neck because I can push most all of the case in with my finger. If it was a problem with the mouth or whole neck i wouldn’t be able to get it close to bolt closure. If I try a different bullet and don’t seat it past the neck shoulder junction it shouldn’t bulge the case out like that should it ? I can try this evening

 

[DLT]

Reply. Clean the throat real good with JB or something similar. Sounds like a carbon ring build up.

Frank

I cleaned it all up with a brush and jb as stated in my first post I believe. There was a ring there but it wasn’t much I wanted to make sure it was gone first and not causing any issues

 

[Chilly807]

Yes, a bullet that doesn't have the bearing surface extend into the case past the neck/shoulder junction will fix the donut issue in the short term. However, that thickened area will keep moving forward as you continue to full length size the brass, about 5 thou each time it's fired.
The donut will move to the outside of the case when you seat a bullet (causing hard chambering), then moves to the inside when the case is resized.
Lapua 223 brass is known for this problem.
As mentioned above, you'll usually feel a bump in seating pressure as the bullet goes past the donut.
I mark my loaded rounds with a "D" when I feel a donut as I'm seating bullets, so I know that case has issues.
In my rifle, the donut doesn't cause hard chambering unless it's pretty bad.
It will, however, cause somewhat higher pressure as the neck expands to release the bullet upon firing.

 

[DLT]

Yes, a bullet that doesn't have the bearing surface extend into the case past the neck/shoulder junction will fix the donut issue in the short term. However, that thickened area will keep moving forward as you continue to full length size the brass, about 5 thou each time it's fired.
The donut will move to the outside of the case when you seat a bullet (causing hard chambering), then moves to the inside when the case is resized.
Lapua 223 brass is known for this problem.
As mentioned above, you'll usually feel a bump in seating pressure as the bullet goes past the donut.
I mark my loaded rounds with a "D" when I feel a donut as I'm seating bullets, so I know that case has issues.
In my rifle, the donut doesn't cause hard chambering unless it's pretty bad.
It will, however, cause somewhat higher pressure as the neck expands to release the bullet upon firing.

Ok thanks. I have a 22-250 that’s shooting lapua brass with doughnuts and has been for a long time. I have kept an eye on them. My bullet doesn’t seat down to it but it’s not moved in the least it’s just hanging out at the bottom of the neck. I guess I’ll try and ream the 223 brass out or shoot a different flavor of brass as lapua is too expensive and too hard to come by to have wasted in so few shots 223 brass terms anyways

 

[SeabeeKen]

The flare is gone on loaded rounds. Dont know if it is after my mandrel is run through them though as I just noticed it this morning
View attachment 1564569

Maybe my old eyes but there looks to be a slight bulge at the base of the neck just above the junction with the shoulder, Makes me thing a donut has formed and is being pushed outward at that point. What is the measurement on the neck of loaded round. Measure at top, middle and bottom of neck
Another way to test this is to seat a shorter lighter bullet that doesnt protrude to the base of the neck and then see if the round chambers

 

[drop_point]

It looks like the issue is the neck length. There is a mushroom around the mouth of the case in the photo, so much that you're measuring it with the mic rather than the neck. You can see light under the mic. Trim/chamfer/deburr and it should fix the issue.

 

[DLT]

It looks like the issue is the neck length. There is a mushroom around the mouth of the case in the photo, so much that you're measuring it with the mic rather than the neck. You can see light under the mic. Trim/chamfer/deburr and it should fix the issue.

Yea I know that I only posted that picture on the white paper background to show the amount of flare they did have. Once I mandrel them even long the flare is gone. When sizing I made sure last night the case mouth does not come out from the top of the die it stays inside the neck area. I’d say it’s another .040 before the neck of the case was to clear the hole in the die. If I was a betting man I would bet the flare has always happened but using the expander ball it evened it all out pulling it back through therefore I never got to see it

 

[sfinn1]

I have seen this before. Measure loaded outside neck dimensions of different case brands. I have a .223 rifle that does not chamber Lapua brass well but will chamber Winchester with no problem. Not all .223 reamers are the same.

I would also add, check overall case lengths. Too long will jam in the chamber neck. Perhaps trimming is all you need.

 

[DLT]

I would also add, check overall case lengths. Too long will jam in the chamber neck. Perhaps trimming is all you need.

I did, I have been on a hard mission since Monday even to find out what exactly is going on. Well today I did 100% for sure. I have doughnuts in just about every piece. Couldn’t feel much at all sizing with expander ball or with my mandrel. Once in a while I could feel a slight bump seating a bullet but not every time. I did not think much of it as I have other rifles that had doughnuts but they must have been clear of the base of the bullet. Anyways I learned that ever so slight contact where there shouldn’t be will cause a lot harder bolt close than I would expect. I also learned that my doughnuts would barely ever so slightly remove sharpie, I had to look really really close to see where the contact was. As hard as my bolt was closing I figured sharpie would be completely gone and brass gouged up but I had absolutely none of that. I hate I have them but I do what to look for next time. I want to thank everyone who chimed in and offered advice. New to me problems always throws me for a loop. Many times you guys are my heroes

 

[L.Sherm]

Are you talking donuts on the outside or inside of the neck?

 

[DLT]

Are you talking donuts on the outside or inside of the neck?

They are on the inside for sure. When I seat a bullet it swells the rear of my neck at the shoulder junction.

 

[memilanuk]

They are on the inside for sure. When I seat a bullet it swells the rear of my neck at the shoulder junction.

I take it you're not using a mandrel to set the inside neck dimension during case sizing?

Still kinda wondering how it didn't show as a wear spot with the Sharpie...

 

[DLT]

I take it you're not using a mandrel to set the inside neck dimension during case sizing?

Still kinda wondering how it didn't show as a wear spot with the Sharpie...

Correct. I use a standard full length rcbs die then I mandrel to set neck dimension. Once i finally seen the mark i was shocked at how little it was making contact. I could see where the sharpie got touched but it sure wasn’t enough to remove it.

 

[memilanuk]

Correct. I use a standard full length rcbs die then I mandrel to set neck dimension.

That's what I meant. Surprised it was *that* close, that the mandrel wouldn't push the donut 'out' far enough to make contact, but the bullet would. Wow.

Once i finally seen the mark i was shocked at how little it was making contact. I could see where the sharpie got touched but it sure wasn’t enough to remove it.

So... If it removed all the sharpie, you probably wouldn't be able to close the bolt . It was always supposed to be a subtle thing.

 

[DLT]

That's what I meant. Surprised it was *that* close, that the mandrel wouldn't push the donut 'out' far enough to make contact, but the bullet would. Wow.



So... If it removed all the sharpie, you probably wouldn't be able to close the bolt . It was always supposed to be a subtle thing.

Correct.

 

[searcher]

Probably a donut that gets pushed to the outside of the case when you seat the bullet. Probably 30% of my 223 Lapua brass forms a donut within 5 firings of new.

A hard doughnut, combined with brass that was a bit overly annealed led me to the condition the posting fellow is having. When the doughnut was pushed, it caused an expansion right at the crease of the shoulder - just enough to create the hard bolt. Taught me two lessons with one problem.

 

[Coyotefurharvester]

Donuts occur 1. Necking up brass 2. All Lapua brass. I'm I getting the substance of this conversation?

 

[divingin]

That's what I meant. Surprised it was *that* close, that the mandrel wouldn't push the donut 'out' far enough to make contact, but the bullet would. Wow.

Springback? The mandrel pushes it out, but the brass springs back in. The bullet stays in, so no springback.

 

[memilanuk]

Springback? The mandrel pushes it out, but the brass springs back in. The bullet stays in, so no springback.

Maybe. Some pretty thin margins, though, for that to be the case.