Thread: Fireform brass for subsonics .308?

I'm sure this has been answered somewhere before but is it worth fireforming brass and neck sizing .308 brass for subsonics? Do you need to bump the shoulder?

Or fine just to do a full resize.

Just resize as normal

I assume you use a Lee Loader kit which just neck sizes?

Do you have more than one .308, which may have slightly different chambers? If not, then just neck sizing is fine.

If chambers are similar (more likely between .308s as they headspace on the shoulders) you may still get away with just neck sizing and using your reloads in either gun.

A quick test if shoulders need a bump from a full length sizing setup is just chambering an empty neck-sized case you previously fired in that rifle. If the bolt closes easily on it (a slight, buttery, final resistance is OK), then it's fine to reload and it's now perfectly headspaced.

You bump the shoulder when you full length size anyway.

You can get away with just neck sizing. It's all so low pressure that the brass doesn't really expand and you don't run into chambering problems.

So if you fl size some once fired brass and bump the shoulders just enough that they chamber smoothly, chances are you could probably neck size it from that point onwards.

Use brass fired in your dhamber and just neck size it, It will be headspaced for that chamber you will only need to bump the shoulder or full length size occasionally
Sub loads do not have enough pressure to form the case to the chamber and can actually cause headspace problems they have been known to shrink after a few firings
as they work harden and don't expand fully letting the high pressure gas back in to the chamber, If you get sooty shoulders it is the sign the pressure is leaking
back into the chamber, up the powder charge or go to a faster powder.

Originally Posted by Cordite

I assume you use a Lee Loader kit which just neck sizes?

Do you have more than one .308, which may have slightly different chambers? If not, then just neck sizing is fine.

If chambers are similar (more likely between .308s as they headspace on the shoulders) you may still get away with just neck sizing and using your reloads in either gun.

A quick test if shoulders need a bump from a full length sizing setup is just chambering an empty neck-sized case you previously fired in that rifle. If the bolt closes easily on it (a slight, buttery, final resistance is OK), then it's fine to reload and it's now perfectly headspaced.

I use a lee Collet Neck Sizing die.

I was going to us fireformed brass from supersonic rounds. I've loaded up some full resized so will see how I get on. Cheers Folks

Originally Posted by shooternz

Use brass fired in your dhamber and just neck size it, It will be headspaced for that chamber you will only need to bump the shoulder or full length size occasionally
Sub loads do not have enough pressure to form the case to the chamber and can actually cause headspace problems they have been known to shrink after a few firings
as they work harden and don't expand fully letting the high pressure gas back in to the chamber, If you get sooty shoulders it is the sign the pressure is leaking
back into the chamber, up the powder charge or go to a faster powder.

this makes a lot of things with subs make sense
i tend to get tons of fireings out of a case then split when im pretty sure the most stressful thing the case sees is the expander ball as they wernt sealing the chamber and gas was leaking around the neck and back over the shoulder


would annealing reset the work hardening process?

Greetings all,
I have used light loads in my .303 and .30-40 old soldiers and in .308 for light target loads for some years. In my experience full length sizing or bumping the shoulder is neither necessary or desirable. The same applies to sub sonic loads which are usually low pressure. In most loads I used AR2206H at start load or a little less or a pressure of 35,000 CUP. This pretty much eliminates case stretching in the chamber and you may see the primers backing out a little. For a neck die the Lee Loader and the Lee collet dies are very good but the latter demand neck annealed cases for the best results. Currently I anneal after two or three firings but will probably move to each firing in future. Some conventional neck and FL sizing dies grossly over work the necks which the two Lee dies mentioned do not. The Redding bushing dies are very good as well.
Regards Grandpamac.