Thread: ADI book max’s

Originally Posted by Nathan F

I would have thought of the adi book max is a compressed 26gns and I went to 26.5 with no pressure signs it will be safe enough. The book max is for good reason very conservative for good reason especially in the states no ?

Greetings Nathan F,
I had a look at the Hodgdon pistol data for the .223. This is for a 15 inch barrel and shows a loss of around 450 fps from a 24 inch barrel. Your 16.5 inch bareel will lose a little less but will certainly lose 300 fps or a little more. Extrapolating from the Hodgdon max to your load of 26.5 grains of H4895/ AR2206H and deducting velocity lost due to the short barrel leaves us with 2,800 fps or 2,750 fps for the max load. Something is driving up the velocity and hence pressure. I don't know if this is the projectile or the case or something else but something is doing it. Add to this the Hodgdon data you are using is very old and pressure is measured in the copper crusher mechanical system. Data for IMR 4895, quite similar to AR2206H, is measured in PSI and the loads for this projectile are a full grain less. The pressure estimate for your load of around 70,000 PSI in a previous post looks pretty good. Please don't wear a Tikka bolt shroud for the sake of a 100 fps.
Regards Grandpamac.