reloading for an AR15

[jimo]

I have just become the proud owner af an AR15 thanks to my grandson. My question is can I reload by just neck sizing or must I full length resize each time?
I have never owned an automatic rifle before and have always heard you must full length resize each time a case is fired in the rifle.

[versifier]

Welcome to The Guide.

You heard it correctly.

With a few individual rifles you might be able to get away with neck sizing to a point, but mostly to insure reliable feeding you need to FL size for semiautos, AR's included.

Rarely you will also run into one with a chamber that requires a small base sizer die for reliable function, but most production chambers are large enough that they are not necessary, especially in military/milsurp rifles.

There are other differences that need to be taken into consideration to keep within the functional envelope of the gas operated action. This puts limits on powder selection and on the upper and lower ends of the charge tables, compared to those for other actions that are manually operated.

If you don't have one, I suggest you get yourself a copy of the current Sierra manual. It has a very well written chapter explaining loading for semiauto rifles, and it includes not only a lot of specific AR info, it also has a special section of loading data just for them. It's an interesting read if you own one or not and the specific loading data is the icing on the cake for an AR shooter.

[runfiverun]

i use a powder that's on the fast side in my ar's.
and can get away with one sizing, one neck sizing, in them [i have to separate the cases if i do this]as one has a tighter match chamber.
the faster powder allows the pressure to drop before the case is pulled from the chamber getting me a couple of extra loads on the case too.
i am limited in my bullet selection with the powder however, so i have to stick to 55 or 60 [home swaged] gr bullets with the powder load i use.
and the 60's are right close to maximum.
if i am going to use the rifle for something like prairie dogs or something like that i make sure they are full length sized.
i give up a little accuracy for 100% reliability.

[Paul B]

I haven't loaded for an AR in several years now. The ones I had had NATO spec chambers and I just full length resized my brass. I sold both of them off as I just didn't like them. With the large amount of brass I had after selling them, I figured I might as well get something to use it in so I bought a Kimber M84 Super America I spotted at a gun show. I use 25.6 gr. of W748, Winchester small rifle primer, milsurp brass and a 55 gr. Winchester bulk bag bullet. Groups from the Kimber run just under a dime when I do my part. The load was left over from when I had the AR's and the Kimber just loved them. Got lucky on that one.
I did the load work up for my ex-son in law's AR and it liked 26.0 gr. of W748.
The ARs I had were the politically incorrect pre-ban versions.
I can't believe that I'm actually thinking about getting another one but yes, I really am. I must be nuts.
Paul B.

[mortre]

I've always full length sized brass because we have 2 AR-15's and a .223 bolt. In the past I had kept separate loads for the bolt and the AR-15's, but in the interest I of keeping things simple I tried my bolt action loads in one of our AR-15's a few weeks back.

My specific powder is not listed in Sierra's manual for their 69 grain bullets, but it's dead middle of the powder manufacturer's range for 69 Matchking's. It didn't cause any issues, but you could really tell a difference in recoil and it was rough on the cases. I had brought a box of commercial match bullets to compare them to, and the reloads had about 100 fps more velocity and the casing were beat up to boot. So I am going to stop loading that specific recipe start from scratch using the AR-15 manual to work up loads that can keep the bolt action and autoloader's happy. That's just my experience so take it for what it's worth.

[S.B.]

I've known people who have shot these in competition and had to use small based resizing dies? To get them to chamber properly.
Steve