5mm Remington Magnum Ammo B.C.

[218bee]

Does anyone know the B.C. of the 38 grain HP used in the Remington factory ammo?

[218bee]

I found a trajectory chart online showing that the old Remington ammo was +0.5" at 50 yards, 0.0" at 100 yards, -3.9 at 150 yards with a muzzle velocity of 2100 f.p.s. If I work my way backwards with that information it looks like the B.C. would be .160, does that look right to you all?

[TinMan]

218bee, that sounds reasonable to me. If you or a friend have a chronograph, it might be better to do the ballistics with real data chronogragh at several distances. Some years ago I did that with some 22lr ammo. Most of the 22lr B.C.s ran about 0.155-0.158, as I recall.

[218bee]

Originally Posted by TinMan

218bee, that sounds reasonable to me. If you or a friend have a chronograph, it might be better to do the ballistics with real data chronogragh at several distances. Some years ago I did that with some 22lr ammo. Most of the 22lr B.C.s ran about 0.155-0.158, as I recall.

Thank you for the response TinMan. I do have a chronograph and at the muzzle I was getting an average of 2048 f.p.s What other distances would you check?

[TinMan]

I would do several targets at convenient distances like 25yds, 50yds, 100yds and 150yds. First try to sight in at 0.0" at 100yds, then measure the P.O.I. rise or fall at the other distances.

[flyrod]

I would've guessed around 0.1 G1. One of those Lab Radar setups would get you a good answer.

If you can shoot at a decent known distance (500+ yards?) and you have a chronograph then just record the MV and drop at distance (from a zero at a known distance) and back calculate with a G1 BC like you already did. Air temperature and altitude can be a factor too. That should get you pretty close for the useful range of that round.