I have no experience with IVI brass. I would never have thought 40.5 grains of H4895 would get a 168 going as fast as 2760. Too hot in that brass IMO.

I've been doing some chrono testing lately comparing the Hornady 168 bthp and the 168 Sierra Match King. The rifle is a Rem 40X with a generously throated 7.62 NATO spec chamber in its 27" barrel. In SIG brass loaded with 42 grains of recent production IMR 4064 the Hornady produced 2630 fps while the Sierra produced 2600. Nothing is free, so the Hornady is quite likely generating more pressure. Something to keep in mind if you're referencing classic M1A loads which used Sierras more often than not.

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switch the same load to LC match brass and it was a little lower on velocity and no issues but higher velocity than I was looking for

What speed did that LC brass produce with 40.5?

The old Lake City M852 match (as loaded with the IMR 4895 of the time and 168 grain Sierras) was spec'd at 2550+/- 30 fps at 78 feet, which corresponds to 2600 +/- 30 fps MV.