I have a .243 and I sighted it in at 100yds a couple days ago with 100grain federal premium noslers. I didn't really fine tune it or anything I just got it so I coud hit like a 3 inch circle. The reason being I'm going out west this year and soon I'll be sighting it in for 200yds. I only have 10 bullets left and will probably use them up sighting it in at 200. Now heres the predicamnet (sp?), I need to buy more shells but I have always heard to buy from the same lot number. I'm assuming I will not be able to do that sinc they have a whole new kind of box so its probably not the same lot. How will this affect my accuracy?

I can’t see there being a problem if it’s the same manufacture with the same bullets. Maybe if you were doing target shooting or for varmint shooting. This is the first time I hear about buying shells from the same batch, I guess I could be wrong and it wouldn’t be the first time.

I have heard the "same lot" theory before, but with quality control being much better these days, it should not really be an issue, especially if you are using premium ammo!

Buy a couple, maybe three boxes, preferably of the same lot #. Shoot the ones you have at 200. Make any adjustments you need to. Shoot a group from your new boxes, adjust if needed. It's my guess you won't be more than an inch or so different, but it's best to make sure. You have 1.5 or 2.5 boxes left to hunt with.

Sure, it can make a difference, but not a huge measurable one. I reload most of my ammo, and there is one brand of powder that changes between lots. Thats Alliant. I can shoot 88gr of Rl25 one day, and get 3200fps, then change to a different lot, and be over pressure with 88gr. I proved this once by loading 10 rounds with one lot and another 10 with another. So sure it can make a difference. I never worried about it to much while hunting and never would. I do worry about this stuff target shooting. Thats the reason I buy 8lbs of varget and other favorite powders.

When you buy your new ammo just take a few shots to verify the point of impact and adjust if you need to.

No big deal, problem solved.

I have also found some hodgdons and imr powders that vary quite a bit by lot#s.I had to increase my powder charge by two grains to obtain the same velocity as the previous lot of imr 7828 in my 7mmstw's.One of my 300ultramags shot very well with h-1000 but the velocity dropped by 100fps with the new h-1000 extreme and I can't get decent accuracy with either of the two new lot#s reguardless of the powder charge.The few remaining rounds loaded with the old lot# still shoot extremely well.

I would go with UncleNorby's advice. Don't forget to check your zero out west. Good luck on your hunt.