Thread: .223 for the Roar

Originally Posted by Flyblown

Righto. I'm using ADI 2208, a tad above the max book load. I took it to the point of a slight ejector swipe on the cartridge head and then backed off a touch. ADI brass, bullet seated longer than book specs.

Attachment 193468

When I shot the drop tests, with a 100m zero I was seeing a lot less drop at 200m and 300m that I expected. So I ended up increasing the velocity to 3133fps but I also changed the BC to 0.241 from the published 0.214, which I thought might have been a typo. This is what I asked Speer about but the tech there wasn't convinced. However I remember looking at a couple of other bullets like the Sierra equivalent and they were more like 0.24 so that's what I selected.

Works for me. Dead on at 300m, smoke-a-goat.

...you've got a 16 inch barrel? I cant get anywhere near those velocities with 2208 and my 20 inch barrel. You must have a tighter chamber or bore. With 26 grains of 2208 I get 2784fps. I can get 27.5 grains flush with the top of the case mouth and then I have to heavily compress it, which is doable but it was creeping out a bit later....so I took them apart again. And this is with .223 brass, not the ex mil ADI stuff, (which I understood has less capacity?)
Whats your charge weight for the 3133 fps ?

Originally Posted by JohnDuxbury

...you've got a 16 inch barrel? I cant get anywhere near those velocities with 2208 and my 20 inch barrel. You must have a tighter chamber or bore. With 26 grains of 2208 I get 2784fps. I can get 27.5 grains flush with the top of the case mouth and then I have to heavily compress it, which is doable but it was creeping out a bit later....so I took them apart again. And this is with .223 brass, not the ex mil ADI stuff, (which I understood has less capacity?)
Whats your charge weight for the 3133 fps ?

No, I have a 20” barrel (see above).

Charge weight is 26.2gr 2208, 2.240” COAL so longer than the book spec by some margin, so this load isn’t compressed. Remember the 3133fps is an artificially increased velocity to meet the drop tested ballistics (along with the >BC).

Book speeds for the 24” barrel are about the same as my chrono values with the 20”, so a bit faster than I expected but not dramatically so. The Howa barrels have - for me - been faster than other manufacturers from the get go, and get faster as they break in after a couple hundred shots. This is evident not just with the .223 but also my two 6mm rifles and my 6.5mm, they are all faster than their Tikka counterparts for the same approximate load.

Also the brass is Aussie bought Thales retail stuff, not the ex-military spec stuff. It’s stamped ADI but the headstamp isn’t the normal milsurp style, plus the H2O capacity is in line with other non-mil brands. I have a heap of military spec ADI 7.62 brass here and that’s a totally different kettle of fish to normal .308 brass.

And lastly, this batch of 2208 is definitely faster than the previous batch I had, because when I first loaded the 308 with it I got an immediate POI change (higher) and had to re-do the drop tests. It resulted in a re-validated MV about 50fps more than before.