I recently bought a .243Win single shot HR/NEF Hadi-rifle with a bull barrel. Does anyone know the twist rate for this barrel?
I want to shoot it for accuracy and I was wondering if I should start with a light bullet(55gr) like comes loaded in Winchester varmint packs or the traditional 100 grain bullets.  I will be buying ammo off the shelf for now so I can not afford to do much experimenting.  Is matching twist rate with bullet wt as important as with an AR in .223?
Thanks

I don't know the twist on your NEF, but I would guess it is either 1 in 10 or 1 in 9. Either should stabilize bullets from 55 to 100gr. I have a Winchester M70 in .243 that doesn't shoot 100 grn bullets very well, but is unbelievably accurate with the 55-90 grn ones. A good bullet to start out with would be be the Sierra 85 Grn BTHP. Federal offers this bullet in its Premium line. Another good bullet is the 90 gr Nosler Ballistic Tip, I know Remington has a factory loading. Either of these should give excellent results.

Common Barrel Twist Rate - 1/10
Bore Groove Diameter - .243"

Bullet Diameter - .243"
Maximum Case Length - 2.045"
Trimmed Case Length - 2.035"
Primer Size - Large Rifle

The 243 Winchester most common barrel twist rate is 1/10" but if you have one with a twist rate of 1/9" or 1/9-1/2" then you'll find that the 243 will give its best bullet performance using 100 grain bullets with slower burning powders like i.m.r.4831 powder.

If 1:10 I would start with 90-102 grn.  I'm betting you're likely to be on the heavier bullet end of the scale.  Seriously doubt you'll do much with 55grn - 70 grn bullets.

Thanks for the info.

You can check your twist rate by taking your rifle and clamping it as level as you can get it into a vise.  Take a tight fitting patch on a cleaning rod and inserting it into the barrel so it is into the rifling.  Mark the top of your cleaning rod with a small mark at the top (top dead center) and parallel to the rod near the handle.  Also mark the rod with a mark right at the action.  Push the rod in until the mark at the handle makes 1 revolution and is back to top dead center.  Mark the rod at the action again.  The length between the 2 marks you made at the action is the twist rate.

In .243 I usually always use 100 gr loads. In my Remington 700 Synthetic, the Federal Classic 100 gr SP gives me accuracy as good as any bolt action I have ever owned. And the heavier bullet gives you increased range and more on target energy at these increased distances. But with the single shot you mentioned, you might be better off with an 80 gr bullet. I know a fella who had one of these that didn't group well with the heavy bullets but did well with 80's. Just play around and find something that shoots well in your particular gun.