I'm a long time loader , but this is my first attempt at loading for an ar type rifle. It seems the more I search and read the more questions I come up with. So here goes.

I've seen many post that their brass needs trimming every time ( not my idea of fun). If so is this the nature of the beast with 223 shot through an ar. Or is this issue if an issue magnified by the FLS not being set up properly ? If the FLS is set to set the shoulder back .003 - .005 how often does brass need to be trimmed ?

If trimming is an issue the x die seems a viable option to me. I have read every thing I can find on the x die still I have questions on it.

First rcbs wants you to start with a batch of brass FLS , trim to .20 under max which would equal 1.56 , set the x die for this batch . After this you would just use the x die , and use this load of brass until they were used up.

Fine and dandy . Lets say I'm starting with 500 pieces of brass. This brass was new brass and has been shot once in the same rifle of mine. I seperate these into 2 250 round batches. I run the 1st batch through a seperate FLS ,trim , and set my x die to these cases , then load. I shoot all of these and reload them again only using the x die. This is the 3rd firing , but the 1st trip through the x die. Now I want to load a different recipe. Not wanting to mess up my batch I want to use the 2nd batch of brass. These 2 batches will remain seperated. Here is the question. If I FLS this batch with the seperate FLS die , trim to 1.56 just like the first batch, load and shoot; can both batches be ran through the x die with out re setting it ?

Next what does the x die do to the internal and external case mouth chamfer ?



Thanks

I FL size everytime using dillion die for loading up on my AR and I have found that you don't need to trim after every round, because the brass hasn't streched much at all.

For one, the load called up using the latest sierra manual shows that the max load for the AR is 2 to 3 gr under the max load for a bolt gun. I'm using H335 with a 50gr Nosler BT. Can't remenber how much powder at the moment, but can get you that if you like.

I guess I would not use the X die, or a bump die for my AR. I found that if you do not FL size, it may not chamber properly, where in my bolt gun it was a touch tight, but the bolt closed fine.

I suppose that if you loaded the AR hotter than recommended, you might need to trim after every shot, but I don't see any reason to do this.

This was checking brass in a colt AR and a Rock River AR, with a remington model 700 bolt gun.

I hope I can alleviate some of your concerns.
I have been shooting AR-15s in high power competition for just north of ten years. And shooting for fun for over twenty. Rarely have I had to trim my brass. I have been using my cases for eight to ten loads before they get ratty enough to toss.
The keys are. Don't hot rod your loads. Find an accurate load at a reasonable velocity.
When you resize don't over resize the case.
Be sure to use a little lube inside the case necks, or use a carbide expander.

muck

Thanks guys that helps.

One more question my rifle has a mil spec 5.56 chamber. Is the headspace on a 5.56 chamber the same as a 223 ? I know the throat is supposed to be longer on the 5.56.

Same chamber, different throat.

Just make sure you have a good brass catcher or all your careful preparation will be undone by getting someone else's brass thrown into the mix. I FL resize and then check OAL before doing the rest of the steps on my progressive. You'd be surprised how often I find necks that have split during this process too.....

Cheers,

Dan