Over size 1x fired Norma 300 WSM brass

[Laguna Freak]

Laguna, I had a base sizing issue with my Tikka 300 WSM. Did a lot of research and reading. There are a few die options, shell holders won't fix 0.557" base.

I managed to find a Wilson size die that fits my chamber really well when following the wheeler video for die/chamber fit.

Eric Cortina just released a mandrel die that also sizes only the base for this very issue. They are under $100 and work! I bought one for me and one for my father in laws 270 WSM that was having the same problem.

Other option is the Micron die mentioned earlier. Ryan Pierce sells them and says they will size the smallest of any die out there. Bullet central also sells them but a single die is pushing $300

I looked and looked to see if I could find a Larry Willis type die or a bulge buster type die I use for my 10mm. None exist and with the slightly straighter walls you can't use 300 RUM and remove material off the bottom of the die.

Is this the die you are referring to?

Expanding Mandrel Dies | Cortina Precision

The expander mandrel die holds the expander mandrels which. Our expander mandrel dies are compatible with 21st Century expander mandrels. You can buy our

www.shootsmallgroups.com

 

[doverpack12]

Is this the die you are referring to?

Expanding Mandrel Dies | Cortina Precision

The expander mandrel die holds the expander mandrels which. Our expander mandrel dies are compatible with 21st Century expander mandrels. You can buy our

www.shootsmallgroups.com

Yes that is the one

 

[Laguna Freak]

Yes that is the one

Do I need a mandrel too or just the WSM die? Thanks for your help!

 

[doverpack12]

Do I need a mandrel too or just the WSM die? Thanks for your help!

Just the die. Mandrel expands inside of the neck. Assuming you don't want to expand your necks after sizing then you do not need a mandrel in addition to the die to fix your 0.557" base diameter

 

[bonie]

In Erics description it states that the die will resize the base.

 

[bonie]

Do I need a mandrel too or just the WSM die? Thanks for your help!

In Erics description it states that the die will resize the base.

Its Only $65. I had a base issue I solved with a cheap 6.5 PRC die , I cut the top of the die off just below the shoulder and ground the bottom a touch. this allowed my cases to go further in the die without bumping the shoulder. It takes some patients to set up but it allows me to size down to the 200 line or even past. Had Eric come out with that die earlier It would have saved a lot of work.

 

[Laguna Freak]

My experience with case head re-sizing:

I bought the Cortina Precision expanding mandrel die for WSM and re-sized 20 cases. Interesting thing is even though the die ID measures 0.551", it wouldn't get my case heads consistently down to 0.555". I kept getting the occasional 0.556" even after working the brass in the die a few press cycles. 0.556" was still a snug bolt closure even after bumping the shoulder back to my chamber's 1.740" = 0.002" clearance. I had to cut the top of my shell holder down about 0.030" to get 0.555" which chambers nicely. Hoping it didn't make primer pockets too tight.

 

[Idahank]

Just get a RUM sizer to run them into. Web diameter is .550" instead of the WSM's .555" don't use a SAUM die though, or you'll push the shoulder way back and likely have a case head separation.

 

[doverpack12]

Just get a RUM sizer to run them into. Web diameter is .550" instead of the WSM's .555" don't use a SAUM die though, or you'll push the shoulder way back and likely have a case head separation.

I believe the RUM has more taper and will hit the outside edge of the WSM shoulder.

 

[VinceMule]

Question: what is the web dia of Winchester when new, what is the web dia of Norma when new?

 

[Idahank]

I believe the RUM has more taper and will hit the outside edge of the WSM shoulder.

True, but it's only .0065" difference at the body/shoulder junction of the WSM. Use a good case lube for the resize. That .0065 will squeeze in just fine and fireform back out. Headspace might tighten by a minutia IF the shoulder gets a slight convexity from the body squeeze, but I'm sure the bolt will still close just fine.

Either way, it's a helluva lot better than running the brass deeper into the die and consequently setting the shoulder way back. You'd have to move the shoulder back .090" for every .001" decrease in diameter. That increase in headspace is dangerous, and begging for a case head separation.

 

[Idahank]

My experience with case head re-sizing:

I bought the Cortina Precision expanding mandrel die for WSM and re-sized 20 cases. Interesting thing is even though the die ID measures 0.551", it wouldn't get my case heads consistently down to 0.555". I kept getting the occasional 0.556" even after working the brass in the die a few press cycles. 0.556" was still a snug bolt closure even after bumping the shoulder back to my chamber's 1.740" = 0.002" clearance. I had to cut the top of my shell holder down about 0.030" to get 0.555" which chambers nicely. Hoping it didn't make primer pockets too tight.

…I really hope that didn't alter headspace much. If you have to do that same thing again, please make a poor man's headspace gauge with one of those resized rounds. Stack up circles of tape on the base of the case (obviously not up over the rim) until you can't close the bolt. Measure the total tape thickness (squeeze calipers to replicate the cam force of the bolt) of the last layer that you could squeeze closed and that will be your approximate headspace. Case head separations occur with a cumulative headspace (each shoulder bump counts into this) of around 0.015"

 

[Laguna Freak]

…I really hope that didn't alter headspace much. If you have to do that same thing again, please make a poor man's headspace gauge with one of those resized rounds. Stack up circles of tape on the base of the case (obviously not up over the rim) until you can't close the bolt. Measure the total tape thickness (squeeze calipers to replicate the cam force of the bolt) of the last layer that you could squeeze closed and that will be your approximate headspace. Case head separations occur with a cumulative headspace (each shoulder bump counts into this) of around 0.015"

The Cortina die does not touch the shoulder / alter headspace. At only 0.001" smaller diameter than Cortina's WSM die, the RUM die "might" work in one press cycle for case head resizing in this instance but then I must burn components to fire form the shoulder. That's not a desirable result for me. After using the Cortina die, I still had to bump the shoulder back with my Lee FL sizing die to fit my chamber. In my circumstance, I think the Cortina die is the best solution other than selling the brass to someone with an AR platform or oversize chamber and then trying to buy new for double what I paid for these cases. Last week I couldn't find any new Norma brass anywhere. At this point, as long as primers will seat, I don't mind running the press a few cycles to work the heads to 0.555".
Once I got it set up with cut down shell holder, its mindless work.

As others have stated, brass flow from firing should make this a one time operation. I'll let y'all know if the heads get bigger after firing.

 

[Laguna Freak]

Question: what is the web dia of Winchester when new, what is the web dia of Norma when new?

I think its about 0.554". I've got some of both. Will try to remember to post up the dimension.