Hi All,
First post. Glad I found this place! I got tired of trying to get my AR-15 to group factory ammo, so I took to reloading. The groups are waay better now! I just have an issue with bullet seating depth I'd like to hear ya'lls opinion on.

I got a Hornady OAL Gauge (http://www.6mmbr.com/catalog/item/1433308/977259.htm). I chucked up a few various bullets in my 5.56 barrel to find out where the ogive engaged the rifling lands. I was terrified when I saw COL readings of 2.35"-2.45" depending on the bullet brand/weight! So with the max COL of 2.260" (which is the spec for .223 and 5.56) that means the tightest fit I can achieve is .090"- .100".

The instructions for the tool said to seat the bullets .020-.040" off the lands. Personally I think .040" seems too huge for a .223/5.56 bullet. A reloading buddy of mine said .010" was the best. Of course none of these specs are reachable unless I make loads that are too long to fit in the magazine.

Also how much of a difference is there in freebore between a barrel chambered in .223 and 5.56? I heard the 5.56 has a longer and wider freebore to accommodate for higher case pressure (which since the max COL is 2.260" that would explain why 5.56 barrels are less accurate than .223 chambered barrels).

How much should I be concerned with bullet seating depth anyway? Should I load to max length to fit in the magazine and forget about it?
Thanks!
~Dan

I'd just stick to mag length. They tend to have very long throats, even with a 223 chamber. Not to mention, carelessly single loading an AR has got to be them number one cause of slam fires. OAL is a fine tuning thing most of the time, and certainly not something to worry about with a factory AR.

I agree with michael.tx: If you can't fit the shell into the mag, why have an AR? ARs are not exactly target rifles, so .010" or .040" off the lands is not worth the air to argue it. 5.56mm throats are longer so rounds can be breeched and extracted much more reliably under full-auto conditions...