Brass Trim Length Question

[BoomFlop]

So, I'm a new Reloader. I just purchased 500 pc (502 to be exact) of 223 Rem Starline brass.

I was not going to resize them, as they range from 1.4550-1.4560 from base to datum with a .330 bushing which is smaller than the 1.4596 minimum. I was just going to run a .222 mandrel through the necks to get consistent neck tension.

Now my question:
The case lengths range from 1.7510-1.7460. Should I trim all of them to the shortest length? Should I leave them and shoot them? I will run mandrel and check again, chamfer and debur regardless.

Thanks,
Steve

 

[ShtrRdy]

I would just shoot them as new brass.

 

[jimbires]

if they are under the max saami length shoot them a time or two before you trim them . when the brass expands to fit your chamber it can get shorter in length .

 

[19 Badger]

I would shoot them once to let them fire form to your chamber. Then you can trim them all to uniform length and work on load developement from there.

 

[BoomFlop]

So you all wouldn't square ends to clean them up? Just run over mandrel, chamfer, debur and load?

 

[jimbires]

So you all wouldn't square ends to clean them up? Just run over mandrel, chamfer, debur and load?

correct , I do run my new brass through my full length die . new brass is way undersized so the full length die does not size any more , it only makes sure it's round for ease of chambering .

 

[rsmithsr]

a) find out what your actual chamber neck length, sinclair sells a tool.
b) fl size with a bushing to give you the tension you want
c) monitor case length and trim back maybe .010 from your chambers neck length.

 

[BoomFlop]

I do not have a bushing die. I only have a full length die. I am planning on removing decapping stem and using a Sinclair .222 mandrel to open necks to proper size.

 

[aushunter1]

I have shot new brass like Lapua straight out of the box BUT that's because of the case prep they do from the factory being quality brass.
I do however check all the case mouths as they can get dings from
After the 1st firing I then go through all the trimming(if required, primer pocket uniforming, chamfer, debur etc process.

I cant vouch for Starline brass as I have never used it but it wouldn't be a bad idea to run the mandrel through it at minimum, chamfer & debur.

If I was using once fired factory brass then I do all the case prep so to start from scratch being all the same.

 

[BoomFlop]

The web and shoulder measurements are also all smaller than SAAMI specs, so I'm not sure what fl resizing will accomplish other than size the neck? The id of neck is .2215, and I plan on running it over a mandrel to get it to .222. I can trim all brass to the 1.7455 to clean up and square up mouths or shoot them as they are?

I can pull firing pin assembly and try them all in my chamber, however, I do not see how they wouldn't be way undersized? I may do this just for practice anyway just to see.

I want the best accuracy I can, however, I am not shooting a bench rifle and will be starting load work up.

Thoughts?
Steve

 

[aushunter1]

More often than not after shooting new brass the case length shrinks slightly as brass is pushed to chamber size, so if you trim to length now it will be even shorter!

Also on FL sizing, this will elongate the brass until it hits the bump back area of the die to on the Datum case.

The only thing

I usually use fired factory cases to get my headspace measurements so I can then set up my die correctly. I presume you have some fired cases?

 

[L.Sherm]

If your going to run them through the .222 mandrel theres gonna be atleast .0005 spring back and could very well be .001 depending on the brass which is not alot of neck tension.

 

[L.Sherm]

Be careful measuring your bump on once fired brass depending on how hot your loads are could take 2-3 firings to be fully fireformed to your chamber.

 

[BoomFlop]

Wouldn't spring back create more neck tension? Confused

If the inside neck is .2215, and I open to .222, wouldn't sling back out it back at .2215? That would be .0025 of neck tension correct?