Issues trying to work up 50-52 gr .223 loads help

Unclenick,

My CZ has a lot of rounds down the tube (6100 rounds) and I don't use it much anymore.
Even then, it still shoots about the same.

I recently experimented with 77 grain Sierra bullets after I found my Savage 12 FV .223 with a 1:9 twist shot them best.

I was surprised that the old CZ 527 shot them better than the 69 grain Sierras, just like the Savage. The CZ still shoots great, but I don't load near Pmax and I keep my barrels clean of copper.

I haven't found that .223 cartridges are hard on barrels. My new Savage 12 FV already has almost 4000 rounds down the tube.

I'm not sure that I am a good enough shooter to notice the difference.
A superior shooter might be able to see a slight drop in accuracy.
But those most recent groups with the 77 grain Sierras were some of the best groups I ever shot with the CZ.
 
When a barrel is shot out, you'll notice it. It's not a smooth transition. You just start getting fliers you weren't responsible for, and they get more and more frequent until the overall groups are bigger. When I shot out my first M1A barrel, it took a season of weekly club matches for it to go from one flier in 20 to one in 5. The fliers were about a moa high and left of the main group, turning 10s into 9s on the MR31 targets, to give you some sense of the magnitude.
 
Rimfire5 said:
CAUTION: The following post (or a page linked to) includes loading data not covered by currently published sources of tested data for this cartridge (QuickLOAD or Gordon's Reloading Tool data is not professionally tested). USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assumes any liability for any damage or injury resulting from the use of this information.

Best loads with N133 and 52 gr SMK #1410 bullets:
With CZ 527 Varmint with 24-inch barrel:
VV N133 23.0 gr at 2.263 O.A.L. @ 3089 fps. trim length 1.751

With Savage 12 FV .223 with 26-inch barrel:
VV N133 22.7 gr at 2.265 O.A.L. 2 3105 fps trim length 1.750
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Wow, I’m impressed. Good on you answering a thread that’s been dead for over four years.
 
I compared barrel life competitive shooters got with different cartridges and powder charge weights. Most interesting was cartridges using 1 grain of powder for each square millimeter of the bore cross section area got about 3000 rounds of best accuracy. Post #5 in:

https://thefiringline.com/forums/showthread.php?t=530505&highlight=barrel+life+spreadsheet

Cartridges using 40 percent more powder got half that; about 1500 rounds. Twice as much, about one fourth or 750 rounds.

Sierra Bullets test barrel lives compared favorably with that formula.

https://www.accurateshooter.com/technical-articles/excel-formula-predicts-useful-barrel-life/
 
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In all fairness, he is talking 223 not 5.56....
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why would that matter??

and beating one manual's listed "max" doesn't impress me much, either. Velocity figures are not "carved in stone" and a different "identical" barrel shooting the same ammo can be 100fps faster than another. Not terribly common, but far from impossible. I've seen it, more than once.
 
44 AMP said:
why would that matter??

and beating one manual's listed "max" doesn't impress me much, either. Velocity figures are not "carved in stone" and a different "identical" barrel shooting the same ammo can be 100fps faster than another. Not terribly common, but far from impossible. I've seen it, more than once.
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The OP specified the gun is chambered in .223 in the original post. GI ball is not 223 and not a fair comparison.

why does it matter... Because of max pressure
223 is 55,000 psi
5.56 is 62,366

you cannot expect to get the same performance out of a .223 as a 5.56 with a 7,366 max psi difference, and trying to force it could result in a kaboom on your .223.
 
It's not as different as those numbers make it look. The 55,000 psi number is for a SAAMI style conformal pressure transducer for a round running at the same pressure level as the M193 ammo, which NATO never accepted. The 62,366 psi number is for a Kistler channel transducer system measuring SS109 (our M855), which was developed in Belgium to satisfy NATO's objections to M193, and that runs about 6% higher pressure in absolute terms. Interestingly, the CIP adopted that higher number for 223 Remington as well, so if you get European-loaded 223 ammo, you are buying the 6% higher pressure. 6% is well within the variation limits SAAMI has for individual rounds, so it's not dangerous.
 
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