300wsm [norma brass cracks]

[kato59]

Hi guys: I had a new left hand remington vsf in .308 rechambered to 300 wsm,i also replaced the bolt with one from PT&G i finally located some norma brass,very tough to find here in Canada.I have loaded and shot some very nice groups using re17 and 180 accubonds,and now after all 100 cases have been fireformed with this combo i started resizing the once fired cases.Using Forster micro dies i noticed the whole case has wear marks from the die as well i have lost 8 cases due to cracks in the necks right at the neck/shoulder junction,keeping in mind these are once fired only!i can't explain this,my gunsmith told me to Full length resize each time,which i have been doing,it seems like the chamber is oversized thus the wear around the cases.i have been getting some super accurate groups with 67.2 grs of re17 and 168 Nosler B/tips @3250 FPS,but this neck cracking worries me,any thoughts

 

[geargrinder]

Norma brass is usually quite soft and isn't prone to cracking, especially after only one firing.

I'll have to disagree with your gunsmith. What he is is making you do is overwork your brass. You only need to re-size your brass enough to make it reliably fit the chamber. Anything more is reducing the life of your brass. Don't full length size unless that is the only way it will fit in the chamber.

I have some 300wsm Norma brass that has over 10 firings and still going strong.

 

[kato59]

He mentioned that the chamber was cut on the SAAMI min. spec. thus the need to FL Size.I also took my sizing die apart and polished the bore out with crocus cloth and scotch brite to try and eliminate the chaffing/wear off the cases.i have been re-loading for at least 20 years and have never seen this kind of wear and neck cracking before.i have a new bag of Rem. 300wsm brass i might try to see if it is the Norma Brass that is the culprit

 

[lightflight]

I had same things happening with my 270wsm.

my rounds would not chamber after Neck sizing. I was told to FL size. Which worked but I cant settle with that. Turns out my die wasn't setup in press right. Now I can Neck size Only and it works.

Then I had the issue of split necks after once fired... errr. So then I annealed the brass after the first firings and it has solved my issue. gun)

 

[Mikecr]

geargrinder is probably close on this
You can measure your pre-fired/post-fired/pre-sized/post-sized to find the answer better than we can from here.

 

[geargrinder]

He mentioned that the chamber was cut on the SAAMI min. spec. thus the need to FL Size.................i have a new bag of Rem. 300wsm brass i might try to see if it is the Norma Brass that is the culprit

It doesn't matter what he cut the chamber to. If you're sizing the brass more than what is necessary to reliably fit the chamber, you're sizing too much and reducing the life of your brass.

Still, one firing and getting split necks is odd. I'll be interested to hear how the Rem brass works for you.

If it works, send me that crap Norma brass for disposal.