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waveslayer

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Reply with quote  #1 
I know there has been a lot of drama with the Liberty barrels from Satern.  I wanted to post my velocities from pre-scraped and post-scraped barrel.
 
I used a Magnetospeed for the first round, and the second round I used a F1 Chrony with lights as suggested by Klem.  I know there are changes, could be the Chrony, I will verify these once I get out and shoot again.
Weather: 57.8 degrees, Dens Altitude= 1783
Rifle: 18" Liberty barrel with 5R.
Loads:  OCW test with CFE and 123 SST bullets. AA brass with CCI 450's and a OAL (using the Hornady Comparator) 1.643
 
Pre-Srape:
30.4= 2423.33  *Best SD=3.05
30.6= 2432
30.8= 2475.66
31= 2467
31.1= 2467
31.2= 2493.66 *SD=8.08
31.4*primers started to flatten= 2489
31.7= 2509.33 Flat primers
31.9= 2519 Flat primers on 2 rounds...interesting
 
Post-Scraping:
Weather: 49 degrees, Dens Altitude 1566
 
30.4= 2358 *SD=7.071
30.6= 2384.3
30.8= 2427.66
31= 2425
31.2= 2444
31.4= 2460 *SD =19.92, One shot threw this off by 18! 
 
Conclusion:
My velocities have dropped, need to test with the Magnetospeed next and report my findings. 
 
Best loads were the 31.2 (.573")and 31.4 being a tad smaller at .388" post-scraped
Pre-Scraped best loads were the 31.2 (.564") and 31.4 at .585.
 
Also, I remounted the barrel to a different upper that had M4 feed ramps. 
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Borrego Bob

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Reply with quote  #2 
They should have dropped provided you loaded at the same COAL becasue the throat is longer and therefore pressure builds slower. The shorter Liberty barrel throat sends rounds out faster loaded to SAAMI COAL. What COAL did you load? Try doing out to 2.285in and work up a load with LEVER or CFE 223.
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Tedward

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Reply with quote  #3 
I think I got everything but what is your *SD stand for?
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waveslayer

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Reply with quote  #4 
Standard Deviation
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Tedward

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Reply with quote  #5 
thanks but now what does that mean with the #,  clueless here...
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Borrego Bob

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Reply with quote  #6 
Waveslayer have you made it to the range will rounds loaded to GII optimum COAL yet? 
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