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Discussion Starter · #1 ·
75gr Hornady Vmax
48.0 and 49.0gr of IMR4320.
3.150 OAL
22" barrel.
Winchester cases if it matters.

I am short on IMR4064, which is what I used to use with this bullet (@50.0gr), but I have plenty of 4320 on hand and was hoping to make a batch of similar loads with minimal extra development effort.

I checked my (old) Hornady and Sierra manuals and these loads appear safe, but i'm searching for another data point before making the ammo.

For some reason the Hodgdon website doesn't support this powder in this cartridge/bullet weight combo.

Thanks in advance.

13,141 Posts

QuickLoad suggests that load will be completely safe, but shows you can go up to a MAX of 52 grains of IMR4320 (REDUCE BY 10% AND WORK UP), which should give you roughly 3600fps, from a 24" barrel. This would give you a 93% fill rate and ~58,000psi. but that is with a cartridge OAL of 3.050". (Your OAL has the bullet only .200" into the case whereas the shorter OAL seats the bullet to the base of the neck.) If you seat to an OAL of 3.150", and it is still .010" - .020" off the lands, the pressure drops to ~55,700psi.

I'm not sure why Hodgdon doesn't list IMR4320 because they list the slightly faster 4064 and Varget, and quite a few slower powders. Seems like it should do a good job for you.
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