Cause for neck splitting?

[mefizto]

Greetings all,

I have recently shot a Remington VLSS in .221 Fireball. All five rounds I fired split, not merely cracked, at the neck, all the way from the mouth of the case to the top of the shoulder.

I looked at the SAAMI specifications, which list the diameter of the neck of the chamber as 0.2550 and (max?) diameter of the neck as 0.2530.

The loaded round I was shooting, stamped R-P 221 Rem Fireball, measures at the neck on average 0.2470. The fired cases' necks were distorted out-of-round and measure at the largest dimension on average 0.2550.

I have also measured new cases (1) R-P 221 Rem Fireball with an average neck diameter of 0.2460 and (2) Lapua cases with an average neck diameter was 0.2470.

Could the difference of 0.008 (0.2550 - 0.2470) be the culprit?

Kindest regards,

M

 

[1911nut]

I’m goin with “distorted out-of-round”

I’ve shot Swift brass that expanded more when fired without splitting.

defective brass maybe

 

[snert]

Sounds like a materials issue. Maybe just brittle brass

 

[GrocMax]

.245"ish loaded ammo neck OD to .255"ish fired is not uncommon in the 223 bore realm. 223 Rem SAAMI or CIP spec chamber is going to be very close to those numbers. That in itself should not be the root cause.

I'd vote for bad/hard brass, or a wonky chamber.

Was this factory ammo or reloads?

The out of round might be a condition from the split, or a chamber issue. With 5 out of 5 fails its definitely something that needs to be addressed before continuing.

Greetings all,

I have recently shot a Remington VLSS in .221 Fireball. All five rounds I fired split, not merely cracked, at the neck, all the way from the mouth of the case to the top of the shoulder.

I looked at the SAAMI specifications, which list the diameter of the neck of the chamber as 0.2550 and (max?) diameter of the neck as 0.2530.

The loaded round I was shooting, stamped R-P 221 Rem Fireball, measures at the neck on average 0.2470. The fired cases' necks were distorted out-of-round and measure at the largest dimension on average 0.2550.

I have also measured new cases (1) R-P 221 Rem Fireball with an average neck diameter of 0.2460 and (2) Lapua cases with an average neck diameter was 0.2470.

Could the difference of 0.008 (0.2550 - 0.2470) be the culprit?

Kindest regards,

M

 

[Farming]

When I had a 17 Fireball Had the same issue. Annealing the brass fixed it for me. Worth a try.

 

[mefizto]

Greetings all,

thank you for your answers. It seems that the consensus is that the cause is not the difference between the chamber dimension (if it in fact is within SAAMI specification, which I will confirm next), and I should concentrate on the brass.

Kindest regards,

M

 

[ranger3]

Ditto on annealing.

 

[chuckshooter]

Split neck = "needs annealing" no doubt about it

 

[mefizto]

Hi ranger3, chuckshooter,

thank you for the replies, I will disassemble the rounds and anneal the cases.

Kindest regards,

M