Help , split case necks

[Aussie]

I have a friend with a CZ 550 in .22/250 . Using Winchester brass and splitting most case necks on the second firing . Can anyone advise what sort of neck expansion should be expected on a .22/250 factory rifle when comparing fired vs loaded rounds ?
Not sure whether we have an oversize chamber or a batch of hard brass .

 

[Fiftydriver]

Aussie,

Most factory chambers will allow a case neck to open up anywhere from around 0.006" total expansion(0.003" all directions) up to as loose as 0.015" which is as bad as I have seen in my shop. Most are in the 0.008" to 0.010" range.

If he is using virgin brass ans having case necks splits on the second firing, there is something wrong in the set up.

Good Shooting!!

Kirby Allen(50)

 

[LB]

I think a too slow powder and very light for caliber bullets can cause something that looks like a split neck. LB

 

[Aussie]

Kirby ,
Thanks , I'll do some measuring .
LB , Using 760 and 50-52 gn pills . Nothing unusual about the load

 

[Aussie]

Kirby ,
Necks on loaded rounds average .250 , fired cases are .257 so should be within specification . Any other ideas ?
Going to try some Remington brass .

 

[rost495]

brass thats too hard? Anneal a handful and see what happens.