Is it neccessary to neck size ammo that will be reloaded for factory rifles? Does it help in the accuracy?

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If you mean for "bolt-action" factory rifles, then YES , by all means your brass will last longer and you should get better groups by simply neck-sizing the cases. FWIW, less going the $$ benchrest-type route of turning necks and using the excellent Redding Competition dies -- check out the Lee collet die. It uses a 6-fingered collet to squueze just the neck area against a mandrel. By adjusting your die in or out you can control the amount of sizing. Used with their "factory crimp" die you'll get phenomenal results ... I'd bet my life on it!! Tight groups!!

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Originally posted by fetchmax:
Is it neccessary to neck size ammo that will be reloaded for factory rifles? Does it help in the accuracy?

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This is another of those "it depends"..Often it helps factory chambered guns most as they are most often toward the large size of SAAMI specs.....the only way to know for sure is to try it....I would try the "partial full length" way first...set you full length die to size only 1/2 of the neck and see if that helps accuracy? this in for BOLT actions and SINGLE SHOTS....if this helps accuracy then you might invest in a "neck die" such as the Redding Bushing type and use it for loading untill the case needs a full length resizing.....don't size the neck all the way to the shoulder, leave a little expanded to help center the case in the chamber.....you might also want to try a "chamber cast" of your chamber to find the actual size of the neck and body of your chamber and fine tune your brass for neck thickness and bullet seating depth....again this USUALLY helps even/exp? factory guns and loads...good luck and good shooting!!!

Yes, neck sizing will generally improve accuracy. By neck resizing the case will be a perfect fit and perfectly centered assuming your chamber is round.

My .243 shot around 1.75 moa with factory Remington 100 gr corelokt. After necksizing and loading with dipped powder chagre of 42.5 gr of IMR 4831 and 100 gr Hornady spire points It routinely grouped under 1.0 moa. Eventually I rebarreled the rifle to .308Win. MM

Depends. In a bolt action, the first thing to go is often the neck, if the f/l die is adjusted right. The neck in a standard, expander ball die, gets worked as much as in a f/l die. A collet die or bushing die does work the brass significantly less.

Second, if you use a die with an expander ball, your accuracy may, or may not be improved. Since the case is much less supported (or not supported), it is quite easy to pull the neck out of round with the expander ball. Even easier than with a F/l die. Again, this is not the case with the collet or bushing dies, as they have on expander. FWIW, Dutch.

If I neck size a bolt action rifle should I also neck turn the brass? Thanks for your replies.

I have found neck sizing and neck turning both give me measurable improvements in accuracy in a factory barrel. Understand, of course, there are things that need to be done to your rifle that will help tweek it toward the "one holer" we are all looking for.

Neck sizing and neck turning help in a factory rifle. The objective is to get the neck tension even, concentric, and uniform load to load.

Neck turning uniforms the neck wall thickness and provides for a centered, concentric release on the bullet.

Neck sizing in a bolt action keeps the brass fitting the chamber tighter than a full length resize.

You can improve accuracy by uniforming the primer pocket, removing the chamfer on the edge of the pocket so the primer seats correctly.

Then de-burr the flash hole so that you get a concentric flash into the charge. Burrs in the flash hole are often significant and deflect the ignition to one side of the case. Deflection results in uneven ignition.

Varmint Al's Reloading Page discusses all this stuff -- probably in more detail than you'd care to think about:

http://www.cctrap.com/~varmint/arelo.htm