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300 Norma Mag

SAC does not currently offer 300NM, nor does Area419. Both of them are supposed to size the base smaller than regular dies. I am using a recent-production Redding S-Type and I'm having a terrible time with clickers on the 3rd firing because it isn't sizing the base enough. I've found only two other options that might solve the problem - 1) Cortina Mandrel Expander die that also resizes the base smaller than a normal sizing die, and 2) Micron Precision bushing die that sizes the whole case, including the base to a smaller dimension than regular dies. The Micron was out of stock and was expected to be a month out so I ordered the Cortina Mandrel die on Friday, primarily just to resize the base. Then I checked today and the Micron was back in stock so I sucked it up and ordered it too. Hopefully, one of them will stop the clickers. Interesting to note is that I've been using the Redding Type-S in 338NM (same case except for the neck) with no problems since 2014. I have to wonder if my 300NM Redding die (recent production) is out-of-spec.
 
SAC does not currently offer 300NM, nor does Area419. Both of them are supposed to size the base smaller than regular dies. I am using a recent-production Redding S-Type and I'm having a terrible time with clickers on the 3rd firing because it isn't sizing the base enough. I've found only two other options that might solve the problem - 1) Cortina Mandrel Expander die that also resizes the base smaller than a normal sizing die, and 2) Micron Precision bushing die that sizes the whole case, including the base to a smaller dimension than regular dies. The Micron was out of stock and was expected to be a month out so I ordered the Cortina Mandrel die on Friday, primarily just to resize the base. Then I checked today and the Micron was back in stock so I sucked it up and ordered it too. Hopefully, one of them will stop the clickers. Interesting to note is that I've been using the Redding Type-S in 338NM (same case except for the neck) with no problems since 2014. I have to wonder if my 300NM Redding die (recent production) is out-of-spec.
Some great info thanks for sharing. What size bushing are you using? 335?
I’m using Lapua brass and Berger 245’s.
 
I bought the jgs 35 norma imp aw reamer and a micron die to match. Had to send it back as it was overworking the body by about 6 thou iirm.

Nice die but it wasn't the best cs. I did eventually receive a working die. 8 sizes in and no clickers but I do get the weird line above the web like most folks at matches I see running 300nm imp chambers.

I top out at 3060 with 87 gr of retumbo and the newer 230 smk
 
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Really interested in the Cortina Mandrel Sizing die. Sizing of the brass is the one thing about this cartridge that seems to be a PITA to get right. Very inconsistent if I would get a clicker or not. I have learned to bump it down 3-5 thou to get it to chamber and not all of the Lapua brass would do it either.
 
No, have not yet tried this custom die…it arrived yesterday.

I have been using Cortina’s mandrel expander dies for .300 PRC, .300NM, and 33XC. All do a nice job of sizing the case body to eliminate “clickers”.

I will report back once I’ve used Cortina custom sizing die.

As for pricing: contact Clay or Mitch at Cortina Precision.
 
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I believe once you have a case that is giving you clickers you are not going to be able to get rid of it with a tighter fitting/resizing die, even a small die. Those will most likely prevent them but I don’t see it squeezing the web back enough. I don’t think a 7/8 die is thick enough for .585 cases also. Best to jump up to 1-1/4 dies. I’ve fought this same issue with the .338 Norma. Less die options for that too. The only thing that has cured clickers is the universal Rollsizer. F class John did a nice review on it. I saw it at shot show this year. Ended up buying one. And it’s legit. It works very well. It’s expensive but considering lapua 338 Norma brass is $400 a box now I justified it.
 
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