223 vs 5.56 brass reduced powder load question

[operavoice]

I know that .308 brass and 7.62x51 brass differ in thicknesses, and the General rule of thumb is to take a .308 load and reduce it by one grain for the 7.62. This method has been effective in my bolt and semi.

Now, most of what I've read is that .223 and 5.56 brass are the same.
Well, I ran into some 5.56 brass that is definitely thicker.
My 26 grain charge weight for Varget/55gr FMJ BT in .223 consistently sits just below the neck.
In this 5.56 brass it sits half way up the neck even after tapping it to settle the grains.

Anyone run into this before, and have a rough idea of a charge weight drop? I know that I can reduce and work up, but for 60 pieces of brass it's barely worth the effort. I can pretty much eyeball where the powder should sit by comparison, it's about .5 grain.
(The gun is a new 5.56 Mini 14, so it can take the higher pressure)

[michaelf3]

I reloaded and used thousands of rounds of mixed brass (223/556). I use the same measurement for powder; thou my reloads are typically a bit slower in velocity than factory loads. Unless you are trying to reach a maximum, I wouldn't worry too much. I use mine for practice/plinking only.

[highpower790]

In most most cases ,little to no difference will be noticed if operating within published specs.
I wouldn’t worry about any difference in cases,unless I was operating at the very top of any load data.

[FLIGHT762]

^^^^^This^^^^^.

223 and 5.56 brass will vary per manufacturer. It can range from 92 grains up to and a little over 100 grains (cases weighed with a spent primer in them). I've done a lot of case weighing. I have a large amount of various 223 and 5.56 brass brass.

Case volume is all over the map per manufacturer. There is 223 cases with less volume than 5.56 cases, just depends on the Mfg.

It will matter if you mix brass and operate at the top of a max load.

It has been my experience that heavier cases have less volume than lighter cases. It was easy to see taking 100 gr. cases and 93-95 gr. cases and filling them with a charge of 26 grs. of Varget. You can easily see the volume difference.

The Varget would almost spill out of the 100 gr. cases.

I segregate my cases just because I'm retired and have the time to do it.

If you're loading a generic blasting load like 24-25.0 gr. of H-335 W/ a 55 FMJ, you can use any case.

When I load my 77 Sierra OTM W/24.3 grs. of Varget, 24.0 of RE-15 or 23.5 of 8208, I use the lighter cases.

[TomReloaded]

LC brass is thicker and raises pressure. In my bolt gun it's noticable with a little more bolt lift force.

But anyway, the max load of varget in 223 is both compressed and below saami max pressure. While the brass is thicker, it's not SO much thicker that you go over safe levels of varget.

You can either just shoot them, or drop lower, but it's safe either way.

[operavoice]

Thank you much!