I have just purchased a new Sport and was wondering which ammo would be the best to start out sighting in the rifle. I know every gun is different but would you use very good ammo or I have a lot of Remington UMC 55 gr would that be the best since that is what I will be shooting the most.

Sight it in using the ammo you intend to fire in it.

This^^

I sighted mine in with TulAmmo because that is what I shoot at the range.

I couldn't ask for any better results.

If I decide to use it for hunting, I will check it with the ammo I will use for the hunt.

67tempest said it best: Sight it in using the ammo you'll be shooting the most of.

I sighted my M4(gery) in with Winchester Q3131 M193 ball using the Santose IBSZ. It's a Colt. Please don't rib me for it.

At practical distances, you're not going to see much difference in POI between 55 gr & 62 gr ball. Or between the products of different makers....unless you run across some old Winchester stuff with a different bullet than currently used. I've got some and it prints about 3" vertically different at 100 yards.

m41,

You answered your own question, it makes no sense to sight it in with different weight or manufacturer for that matter. You should have a blast with your new Sport.

I use a 100 yard battlesight zero with 62 gr. as that is about all I'm interested in for my own use. I have a stash of the MK318 Mod 0,and also Federal Fusion in the same weight.
I buy M855 for training.but 55 gr will work just as well for practice. You can actually zero for a couple of different loads and just mark your settings.

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Blessed be the Lord,my Rock

Not being instantly familiar with that model I would look at the twist rate first then pick an optimal bullet weight. I then initially sight in a 25Meter BSZ then try them further out. I find there is a difference in some ammo with Q3131A being better than most in velocity and accuracy.... in my gun.