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Cabob

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Reply with quote  #26 
I need to get out and test some 120 SST's with SWB as well. The only time that I tried them was with AA2200, and they were horribly compressed and slow....
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Cabob

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Reply with quote  #27 
Wow, I just realized that I commented on this post last Summer.... Doh!  Oh well, at least I remember the results that AA2200 and 120SST's gave me!!! 
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mcintosh

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Reply with quote  #28 
I just got back from the range where I was able to get some 120SST over the chrono.

I’ve got an 18” 1:11 barrel and my load is 21.0grains of SWBO with a Wolf SRM primer.

19 degrees f outside today.

Average - 2447.5
SD - 15.3
ES - 34

1: 2432
2: 2449
3: 2445
4: 2443
5: 2466
6: 2450

Accuracy was acceptable, but I was only shooting 50yd. I didn’t want to walk any further than I had to in the cold.
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kshunter

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Reply with quote  #29 
Good info, I guess I need to find some of these to play with.
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55Gregg

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Reply with quote  #30 
That is great info...I've been very interested in that bullet because it would be so good at stretching the 277's hog range.  I should be able to get up into 2500's with my 20" barrel.  [biggrin]
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Cabob

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Reply with quote  #31 
Heck yeah, awesome! McIntosh, what brass did you use?
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mcintosh

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Reply with quote  #32 
All lake city. 09, or 10.
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Cabob

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Reply with quote  #33 
Sweet, thanks.
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MDWS

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Reply with quote  #34 
Bump.
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Lindenwood

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Reply with quote  #35 
Quote:
Originally Posted by 55Gregg
That is great info...I've been very interested in that bullet because it would be so good at stretching the 277's hog range.  I should be able to get up into 2500's with my 20" barrel.  [biggrin]


This is my exact goal with my new 20! I have 16lbs of SWBO and 300 120 SSTs (and 90 TNTs and even some 130 Interlocks!) to figure something out. 2525fps at the muzzle with the 120 SST gives you 1000 ft/lbs at 300 yards :D .
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55Gregg

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Reply with quote  #36 
Well as soon as I can get my grubby hands on some SWBO I'll start seeing if I can attain that lofty goal.[thumb]
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REDs Reapers

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Reply with quote  #37 
Let me know how it goes! I've got a hand full of the 120sst left over from when I was loading for my .270 - RED
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Lindenwood

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Reply with quote  #38 
Quote:
Originally Posted by Rifter
Looking at your numbers, 21.0 gr. is where I'd stop.  After that point, your fps per increment starts going up.  That tells me you've passed the node and are starting to push the pressure limits.  If you correct your velocity to the muzzle, you're right at 2400 fps, and that is pretty good for a 120 gr. in the Wolverine.  Also, on your last load, it shows the ES is opening up, and that is where accuracy starts to deteriorate.


In my experience and observation, the primary indication of overpressure (with a chronograph) is when velocities start peaking in spite of increasing charges. This is because the chamber is actually just stretching more and more with increasing charges.

At this point in his development, he was actually just approaching peak efficiency!

Much more objectively, using a micrometer to measure the case head, just above the extractor groove, is far more reliable. When I was pushing .45 ACP cases to 60k PSI, I was hand-metering loads to .1gr and measuring and tracking case head expansion down to the thousanths of an inch. It was actually quite easy to track the correlation between charge and expansion.

FWIW, loose primer pockets are a commom symptom of high case head expansion. For a case of this size, I'd venture that loose pockets might correlate to about .008" of case head expansion over new or otherwise unabused brass.

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