.223 & 7mm Mag: FL sizing or Neck only?


PDA






357SigFan
November 8, 2008, 04:14 PM
Which is really better? I've heard it said that you can increase accuracy if you neck size only vs full length sizing. I've been FL sizing my .223's, and just bought a BAR in 7mm, which I'll end up reloading for. I noticed that the casings fired from the BAR are about .013" larger just below the shoulder than they where prior to being fired. Found something similar with my .223's (while the difference was smaller, it was noticable). Should I switch over to neck sizing the .223's (which are being fired from an AR15), and only neck size the 7mm? Given the difference between the factory vs fired with the 7mm, I can see how neck sizing only could extend case life...

If you enjoyed reading about ".223 & 7mm Mag: FL sizing or Neck only?" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
243winxb
November 8, 2008, 04:23 PM
Q. I see a Small Base Die Set listed for my caliber. Do I need these or should I buy a Full Length Die Set or Neck Die Set? How does each set differ?

A. The Small Base Die set is intended for use for ammunition to be used in auto, semi-auto, and lever action rifles so that the loaded round chambers and extracts easily. The Small Base Sizer Die sizes the case from the shoulder to the head of the case a couple of thousandths smaller than a Full Length Sizer Die. In certain calibers it also sets the shoulder of the case back a thousandth or two more than the Full Length Sizer Die. The Full Length Die Set or Neck Die Set is not normally recommended for ammo to be used in auto, semi-auto, or lever action rifles. The Full Length Die set is recommended for ammunition used in bolt action rifles, particularly for ammunition to be used for hunting. The Neck Die Set can also be used to produce ammunition for use in bolt action rifles. The Neck Sizer Die sizes only the neck of the case so it will hold the bullet firmly. It does not size the body of the case nor does it set the shoulder back. Neck sized cases will usually chamber for three or more firings, depending on the powder charge and chamber dimensions. However, over a period of time, a slight drag will be noticed when the bolt is locked. At this point, cases will need to be full length sized and the shoulder set back so they will chamber and extract easily.

http://www.rcbs.com/questions/faq.aspx

GooseGestapo
November 8, 2008, 04:27 PM
I prefer to go with the FL dies for anything except match grade Bolt-actions.

With both of these cartridges, I rely on range-pickups for brass, so FL sizing is the only option. There are wide ranges in the chamber diminsions on both of these cartridges, so you'll likely need to full length size. Especially for the BAR. I doubt that you'll be able to tell the difference in accuracy between full length and necksized ammo. Even with a Rem.700 in .22-250 that will shoot one-hole groups, I'm hard pressed to tell the difference in accuracy between ammo sized in the full lenght die and the Lee Collet neck- sizing die.

Once sized to fit the rifle, I'll back off the FL- die to where the shoulder is just kissed or only slightly pushed back for easier chambering and better accuracy, but positive chambering in my auto's and lever actions.

With anything except an exceptionally accurate bolt action, you're going to be better off full-length sizing.

243winxb
November 8, 2008, 04:27 PM
Most Full lenght resizing dies will work just fine in an auto loader.

rcmodel
November 8, 2008, 04:36 PM
I would not recommend neck-sizing for either an AR-15, or a Browning BAR.
Auto-loaders you know!

Get full-length dies and don't worry about it.

BTW: NO, you do not need small base dies, in case your were going to get around to asking!

357SigFan
November 8, 2008, 05:19 PM
Thanks for the input; the funny thing is when I bought my .223 FL die set at Grafs (a year or more ago), the person there said you should neck size for an autoloader (something about being a gas operated semi), and thet FL was usually used for bolt guns. I got the FL dies becasue that's what my grandfather has used with no issues (although his only .223 is a TC pistol).

If you enjoyed reading about ".223 & 7mm Mag: FL sizing or Neck only?" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!