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  #11  
Old 06-02-2014, 01:49 PM
ackleyman ackleyman is offline
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Default 223 AI pressures

I have three 223 AI's, 9",12", and 14" twists.

I have used H322, AA2015, H335, Benchmark, N133, and N135.

With the 50's and N133, 3750 fps shooting groups between 1/4"-1/3" is typical and 1 1/4"-1 1/2" groups at 400 yards in calm winds is norm. Add 100 fps to the above number for my 27" barrel.

The other powders shoot the 50's into bug holes at 3650, approximately.

With the 55g nolsers in the 12 & 14 twists, N135 shoots tiny groups at 3650 fps in the 23" barrel and 3700+ in the 27" barrel.

The 1-9 twist barrel has a longer throat, the 50's using H335 shoot 1/2" at 200 yards.

Since the topic of this discussion is how to read pressure signs, I would suggest that you use the same technique as you do on any other cartridge with case head scuffing, and increased bolt lift, which is what I have done for many years on this AI and all others I have had.

A few years ago, I had an engineer test 4 different brands of brass for Rockwell hardness, there was a 12% spread in hardness between the various brands of brass. Also, there was up to a 6% variation of hardness within the same brand. So, measuring brass at the web is not a good way to measure pressure because you are going to have soft brass in any lot, and those soft cases will have to be thrown away sooner. The 223 AI has an accuracy node that is high on the pressure, so don't be scared to push the envelope. I think that the whole idea of determining pressure by measuring the expansion at the web was dismissed some years ago because of the above reason.

Now I use Lake City brass of the same year and I would like to add that this brass is tough as nails. IMI brass has been my mainstay for many years, but I believe that the Lake City brass is a tad tougher. I have yet to loose the primer pockets of any Lake City brass, and I have tried to ruin the brass on really hot loads pushing the envelope while testing the Lake City. If you think that you can not shoot really tiny groups with Lake City brass, you are badly mistaken. I like to start off with unfired Lake City brass when I use it.

Good luck
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  #12  
Old 06-02-2014, 05:13 PM
varmintshooter varmintshooter is offline
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Join Date: Dec 2013
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Default

Thanks for the input guys. I don't have all of the powders mentioned but do have h322 and 335 so will try them. I have been using up some IMR3031 with 50 vmax to fireform brass ( LC2012 ). I also have IMR8208 that works great in my 223 and I am hoping it will work in the imp version as well. No pressure signs yet and vel is close to what I hoped for.
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