Case necks not expanding

[gotcha]

Wouldn't that be "improperly annealed brass"?

Call it what you want.................. Just taking my SWAG for what ever its worth Opinions are like noses.

 

[mikegaiz]

I have had a similar problem a while back. It was the bullet was not seated deep enough in the neck. Not enough bullet to neck contact (length). the bullet left the case before the neck sealed. Is the case blackened or dented?

 

[stifffingers]

I have had a similar problem a while back. It was the bullet was not seated deep enough in the neck. Not enough bullet to neck contact (length). the bullet left the case before the neck sealed. Is the case blackened or dented?

I tried to duplicate the event today and wasn't able to. I only fired 10 rounds from the same batch of ammo I put aside for matches. Have to admit the bullet isn't seated too deep into the case. It's a 67.5 BT that can't be shot from a jam. It has to be jumped and I'm guessing it is about .050 to .060 of bearing surface into the case neck. I'll have an exact measurement tomorrow when I do some more reloading. No sooty necks or dents. Guessing I may have to change the bullet I am using, I loaded some 80grFB using old data, didn't have any problems.

 

[stifffingers]

I tried to duplicate the event today and wasn't able to. I only fired 10 rounds from the same batch of ammo I put aside for matches. Have to admit the bullet isn't seated too deep into the case. It's a 67.5 BT that can't be shot from a jam. It has to be jumped and I'm guessing it is about .050 to .060 of bearing surface into the case neck. I'll have an exact measurement tomorrow when I do some more reloading. No sooty necks or dents. Guessing I may have to change the bullet I am using, I loaded some 80grFB using old data, didn't have any problems.

Measured the seating of the 67.5 grbt today. The bearing surface in the neck is .065

 

[243winxb]

There is no law that says case necks must expand.

As long as the bullets full bearing surface is in contact with the sized area of the neck is should be ok. I would size to just below the bullets base. The bullet ogive should not go below the case mouth when seated.
Bullets that jump, can be very accurate.

I would aim for .002" neck tension.

 

[stifffingers]

There is no law that says case necks must expand.

As long as the bullets full bearing surface is in contact with the sized area of the neck is should be ok. I would size to just below the bullets base. The bullet ogive should not go below the case mouth when seated.
Bullets that jump, can be very accurate.

I would aim for .002" neck tension.

My best question is why did all but five of 25 fully expand to .270 and the five came out .266 or less? All were loaded the same for a match and from the same batch of brass on their fifth loading. The 67.5gr. BT is seated with .065 of bearing surface in the neck. I am loading for .002 neck tension.

 

[snert]

Better question: Where did the bullet go?

 

[243winxb]

annealed

Could some brass be harder or softer?
If neck tension/bullet pull , was not the same, firing of the primer may move the bullet sooner. Resulting in less pressure?

I would want more bullet shank , deeper into the neck. But no deeper then the ogive.

modulus of elasticity- Cartridge Brass-
Material is 70 copper/30 zinc with trace amounts of lead & iron , called C26000. Material starts to yield at 15,000 PSI when soft (annealed), and 63,000 PSI when hard.
Material yields, but continues to get stronger up to 47,000 PSI when soft, and 76,000 PSI when work hardened. /QUOTE] Olin Brass.

 

[243winxb]

The 67.5gr. BT is seated with .065 of bearing surface in the neck

My 68 gr Berger FB has .280" bullet bearing surface, total.
The case neck has .153" contact with the bullets bearing surface.

Seat your bullet deeper, shorter OAL.

 

[stifffingers]

My 68 gr Berger FB has .280" bullet bearing surface, total.
The case neck has .153" contact with the bullets bearing surface.

Seat your bullet deeper, shorter OAL.

The final answer is in. Alex Finley of Annealing Made Perfect tested my brass and the metallurgy is perfect. After more testing it is true the reason the necks didn't expand is because the bullets were not seated deep enough into the cases. I am now testing 80gr. & 70gr bullets and not finding any problems. I can't go heavier than 80gr. the barrel is a 12 twist. I want to thank you for all your opinions and information.

 

[fourpower]

Have a puzzling question. I recently fired 15 6BR rounds, 5 of which the case necks did not expand. All cases are Lapua and on the fifth loading. All were annealed but the necks didn't budge. They should be .270 but are only .266. The neck walls are all .012. Any ideas? I'm going to send some cases to Alex at AMP, he's as curious as I am. I've replied to a couple post before but never posted. Thanks, if you have a solution.

I have also had a problem with new rifle in 7RUM. started with load data on the high side for 195gr berger bullet. loaded neck dia. .315 after firing .320 next time we fired neck dia went down to .309 and neck would click on the die expander ball.went up to way over max loads still no problems with bolt lift. we were using retumbo. cases were all expanding the wrong way. we quit that powder when we expanded the cases head so they wont go into shellholder! went to 50bmg and all are problems went away and gun shoots great. in all my 50 plus years have I ever seen a caseneck get smaller and have brass headspace set back .007 when fired. never to old to learn something!

 

[Alex Wheeler]

I have seen that happen. Its why I believe that necks expand before the bullet leaves the neck, and why seating force has little merit on anything as it not a measurement of the grip a neck puts on a bullet. If the bullet slips out of the neck the neck will not expand like you have seen.

 

[CKshooter]

I have seen that happen. Its why I believe that necks expand before the bullet leaves the neck, and why seating force has little merit on anything as it not a measurement of the grip a neck puts on a bullet. If the bullet slips out of the neck the neck will not expand like you have seen.

Alex, are you saying consistent neck tension is irrelevant for accuracy, or as long as its the same on every round it doesn't matter how much grip it has?

 

[Alex Wheeler]

Alex, are you saying consistent neck tension is irrelevant for accuracy, or as long as its the same on every round it doesn't matter how much grip it has?

Not at all. Tension is what matters most. The numbers off the seating force gauge are mainly friction and only correlate to tension slightly. You have to test tension to see how much your rifle likes. I have even got very bad seat force ES on the dial and shot small at 1k. Tension was consistent even though friction was not.

 

[CKshooter]

Not at all. Tension is what matters most. The numbers off the seating force gauge are mainly friction and only correlate to tension slightly. You have to test tension to see how much your rifle likes. I have even got very bad seat force ES on the dial and shot small at 1k. Tension was consistent even though friction was not.

I appreciate your knowledge. I'm using an arbor press because you can feel friction much better than a standard press. Is that a waste of time? That's part of the reason for the arbor press. The other is less run out.

 

[Alex Wheeler]

No, It does tell you if something is way off. I know some great shooters that sort by the dial readings, so they believe in it. I have not seen anything yet to make me put a lot of faith in the readings. So long as they are within reason. Maybe 10 ES I wouldn't worry. If you get one go way high or low Something is different.