.223 powder charge % drop for 5.56 lake city brass

[hutchster]

I seem to remember hearing that one must take 10 percent off the original .223 powder charge when using 5.56 brass to compensate for the thicker brass, is that correct ?

So if the manual calls for say 25 grains, my math skills deduce the answer to be 22.5 grains of said powder when using 5.56 brass.

Thanks
Hutchster

 

[Spawn-Inc]

Just a guess but if your starting at the minimum loads then you should be fine, you would just hit potentially hit your max before the books say.

/tagged.

 

[hutchster]

Yeah, I just loaded for the minimum, I'm not expecting my 1:9 barrel to love the 40 and 52 grain loads anyways, but worst case they should suffice for destroying old hard drives

 

[LeeEnfieldNo.4_mk1]

just did the same with 7.62x51. Loaded up to a few grains below max, going up .5 a grain starting from the low load. I should notice pressure signs develop as the loads get hotter and stop if they are going to a bad place.

 

[LUTNIT]

I've used LC and IVI 5.56 and 7.62 brass and always just do normal development from regular starting loads for 223 or 308 data. Starting loads are already pretty anemic so I can't see them giving any issues even if the brass is thicker.

 

[BattleRife]

The idea that military brass is thicker than commercial is a holdover from the days of surplus .308 and .30-06. Generally speaking, 5.56mm brass has the same capacity as .223 brass. If you want to make sure simply weigh a few cases. Heavier cases = thicker walls = lesser capacity.

 

[Smcx]

I think that a volume measurement would be a better way to tell.

 

[titch--]

When I switched over to LC brass in my 223 there was no difference.

I did work up a couple rounds to my original load though just to make sure

 

[manitou210]

###222

 

[beltfed]

The idea that military brass is thicker than commercial is a holdover from the days of surplus .308 and .30-06. Generally speaking, 5.56mm brass has the same capacity as .223 brass.

This.

Heavier cases = thicker walls = lesser capacity.

After doing a bit of testing whereby I weighed cases, compared volume and sectioning a fairly large lot of various NATO (IVI, IMI, LC ), commercial and military 5.56/.223 (winchester, Remington, RUAG, Norinco among others) - over 140 cases in total, the average between each brand (20 random cases of each manufacture) I'm not really convinced there are any significant differences in case volume from manufacturer to manufacturer, be it NATO produced or commercial, civilian match ammo.
One of these days I should get around to photographing and posting my findings.

 

[Gunnerlove]

"It depends/ sometimes" is the best answer I can give. I have found Federal, Winchester and Lake city to be close to identical with 25.3 of Varget, filling the case to the base of the neck. However with 25.3 of Varget the IVI case is filled to the brim with zero room for a bullet. So measure the capacity of what you have and confirm what you are working with.

 

[bigedp51]

U.S. military 30-06 and 7.62 brass was made thicker with less internal volume, BUT the .223/5.56 military case is made harder to accomplish the same effect. Also the military Lake City cases have more internal volume than the majority of commercial cases.

Also note Lapua has the least case weight variations and Winchester and Remington the most weight variations.

Also note that Lake City has the hardest brass (Ford Truck Tough) followed by Lapua with Remington having the softest brass.

The information below was posted by CatShooter at Accurate Shooter reloading forum. Brass flow into the ejector hole in the bolt face and base expansion is used as a sign of excess pressure, "BUT" it is also a sign of soft brass and does not actual max chamber pressure has been reached.

The actual Hardness measurements were (.062"x100kg, Rockwell "B")

LC 2008 = 96

Lapua 223 Match = 86

Norma 30-06 - 76 (added n Dec -'14)

Winchester 223 = 69

Norma .220 Swift = 64 (added in Dec '14)

Remington "R-P" = 49

For all you guys that have been saying that Winchester cases were tougher than Remington... you are vindicated, they are a lot tougher!... 40% tougher

For all you guys that think Lake City is surplus junk, nothing could be further from the truth. It is some of the most bestest brass made (it is paid for by the tax payer), so enjoy it!!!

LC and Lapua are the "The pick of the litter"!

When it comes to case weight below is a photo of Lake City cases on the left and right with a Federal case in the center. The Federal case weighs more than the Lake City "BUT" the Lake City case has the strongest base and the most internal volume.

The main point here is you could work up a load with Remington brass and it would show pressure signs long before Lake city brass due to the softer brass

And just like the reloading manuals tell you, any time you change any reloading component you should reduce the load by 10% and work up again.

Below are the pressure ranges with .223/5.56 cases with the same powder charge of H335. The top case is Lake City and the bottom one is a case with the least amount case volume 30.6 vs 28.0 grains of H2O.

I use the above 25 grain load when using mixed brass for my practice blasting ammo at 100 yards or less in my AR15 carbine. And use one brand of case sorted and prepped in my AR15 A2 HBAR and .223 bolt action for accuracy loads.

 

[bigedp51]

The idea that military brass is thicker than commercial is a holdover from the days of surplus .308 and .30-06. Generally speaking, 5.56mm brass has the same capacity as .223 brass. If you want to make sure simply weigh a few cases. Heavier cases = thicker walls = lesser capacity.

This is not criticism but U.S. military 30-06 and .308/7.62 cases are "still" made thicker to better withstand the larger diameter and longer headspace settings on military rifles and machine guns. The .223/5.56 case could not be made thicker because it would lose too much internal volume and decrease velocity. Lake City military cases and military commercial contract cases are made of harder brass to increase the cases strength.

When it comes to the highest quality standards military made Lake City cases are the top of the line .223/5.56 cases.

 

[beltfed]

Wow, good info Ed!

I'll add my numbers that Canadian shooters may find useful:
Brass manufacture / quantity of test sample / average weight grains / extreme spread grains

Israeli IMI (TZZ 88 headstamp) / 20 / 94.0 / 1.4
Norinco (CJ-94 headstamp) / 20 / 95.26 / 2.4
IVI (NATO 87) / 20 / 96.65 / 1.1
PMC (.223) / 20 / 92.65 / 2.1
FNM (15-76) / 20 / 96.67 / 1.7
Winchester (.223 REM) / 20 / 93.08 / 1.8
RUAG (T 94 - Gp90) / 20 / 96.42 / 0.9
Federal (FCD 223 REM) / 20 / 91.05 / 1.2
Lake City (NATO) / 20 / 92.6 / 1.2
Remington (RP 223) / 20 / 92.96 / 0.6
Winchester (WCC NATO) / 20 / 93.76 / 0.8