Savage 12FV in 223 Rem Accuracy Experiences

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THOUGHTS ABOUT MY LAPUA CASES

What can I say about the Lapua cases straight from the factory? In short these are good cases with very tight tolerances. I do have a few notes about the cases in their ‘raw’ form:

• Neck Concentricity: There were two cases in the lot that have dented necks. I know I dropped one on the concrete floor of the garage, which is probably the max concentricity case- you can easily see the dent (picture below). Because I measured all 100 cases however, these two neck defects shouldn’t have impacted the overall numbers however (except the obvious extremes)
  
• Neck Thickness: The Lapua cases have meatier necks than the PMC Bronze brass, which is a good thing because I have more material to work with, and there will be less stretching with each firing since the cases are essentially 0.002” closer to the chamber neck.
  
• Body Concentricity: I don’t know what Lapua is doing, but the bodies are unbelievably concentric. I didn’t record anything below 0.0005” increments when I was measuring (yes, ½ of a thousandth), but in many instances the needle on my gauge was barely wiggling- those are the 0.0000” concentricity measurements...

I’ll have to fix this case neck early in the process in order to prevent the deformed neck from affecting the various cuts and sizing operations. I’ll talk about how I do that when we get to Phase 2 in a few posts. It was an informative and useful 2.5 hour exercise to measure all these parameters, but I’m itching to use some tools to modify the cases...

 

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TARGET LAPUA CASE PARAMETERS

Now that we know what the cases look like from the factory, we can solidify our target dimensions from my past work studying my chamber. Basically these parameters are very similar to the PMC Bronze brass, but I account for potential changes in the Lapua neck thickness and other factors as needed. The following table has all the details.



Alright, now that we know what we want the cases to look like when we are done, it's time to roll up my sleeves and get out to the garage!

 

[243winxb]

A .248" bushing. Interesting. Misc brass loaded rounds necks i have measured are .246" or less. No Lapua .

I would like to see loaded round neck diameters closer to the SAAMI .253" Like the Lapua.

A better fit in the chamber may improve accuracy.

 

[SlowSqueeze]

A .248" bushing. Interesting. Misc brass loaded rounds necks i have measured are .246" or less. No Lapua . I would like to see loaded round neck diameters closer to the SAAMI .253" Like the Lapua. A better fit in the chamber may improve accuracy.

I hear you- the PMC Bronze brass was even smaller, and I was targeting a 0.245" bushing for those cases. I'm happy to see that the Lapua necks have more meat on them. I'm with ya on the 0.253" dream as well!

If anyone knows a case neck that's close to 0.0145" thick let us know!

 

[Evlshnngns]

Weather is nice, any bullets hit a target?