Case sizing

[CouesNStuff]

New to hand loading so I'm genuinely curious on some of the more experienced folks thoughts here. If I have once or twice fired brass, and I take the empty cases and drop them into the action of my rifle and the bolt closes and opens smoothly, is there any need to resize the case? Or what about trimming the case? If I take my calipers and measure the cases, the fired cases are showing different measurements, +-.001 inch. But like I said, they fit in the action and don't hang up at all. So, how often are you guys resizing and trimming your cases?

 

[Ballcap]

You will have to resize the neck to seat a bullet. I would check case length and trim if needed. If they are smooth in the action you should be fine with just a neck size. I would guess you are not loading near max and if that works for you, great, you will get more life from your brass.

 

[Dmoua]

It’s normal for brass to not be fully fire formed with one or two firings. You can full length resize the brass without bumping the shoulder.

As far as trimming brass. Trim five to ten thousands below minimum and it’ll take you a few firings before you need to trim them again. Always trim them to the shortest piece of brass you have. Variance of +- 0.001” is normal.

 

[JFK]

You will need to neck size at minimum. Some people just neck size after firing but at some point you will need to bump the shoulder back a couple thousandths. Other people just full length size every firing. Pros and cons to each way of doing it. A standard full length die with sizing button is probably easiest to setup correctly for a new loader and still makes very good ammo.

Trimming needs to be done when the brass grows and gets close to or exceeds sammi max. This won’t always be something you can verify by chambering a cartridge. Measure your cases after every firing to determine if trimming is needed. When I trim, I trim them back to sammi min length so you get more firings between having to trim again. Not trimming your brass and letting them exceed acceptable length can cause dangerous pressure spikes.

Focus on doing the basics well and build a process so it’s the same every time.

 

[Fireflyfishing]

On new brass, I’ll neck size until the case starts getting snug in the chamber. From there on out for the life of the case I run a reading body die and a lee neck sizer. You could achieve the same results with a full length sizing die. I like the results from the two step sizing process, however. You will get more consistent result when you do load development when your brass has stretched to the chamber and you are full length resizing.

 

[EdP]

Like others said, as a minimum you have to resize the neck to seat a bullet (so it will stay in place) AND you need to check overall case length and trim as necessary to stay between SAAMI specs. Check and trim AFTER whatever sizing you do. Also, if you are only neck sizing and not setting the shoulder back, check that your cases chamber after sizing and before priming them.

 

[Plainsman-147]

I’m of the camp of full length resizing every firing and trimming every 2-3 firings as needed to stay within SAAMI specs for the chamber. As I’ll measure 5-6 or so cases and trim short of the shortest case by .002”.

 

[CouesNStuff]

Thanks for the knowledge share. I also run a Redding press with RCBS dies. I'll have to resize and trim a whole lot of twice fired brass this coming loading session.

 

[nm.otter]

I'm also just getting started, planning to try this

but (at least to start) without the headspace comparator. Scotch tape is pretty close to .002" -- I'll just add another thou via the lock ring.

 

[Mule3006Elk]

I'm a small volume reloader. I don't mind the reloading process. I trim after every firing but my brass grows 0.002 to 0.005 with every firing. I had 300 WM Nosler brass that NEVER grew. My 300 WM Lapua brass does. And to clarify, if the case length is too long when you close the bolt you essentially crimp the case in the chamber, which can cause dangerous pressure spikes. I anneal, FL resize, bump shoulder, use bushing dies, mandrel to control neck tension, trim. I want load-to-load consistency. If I have POI shifts I can't blame the reloading process b/c the order of operations is the same every time. Until my brass is fire formed I don't use said brass for chrono or accuracy evaluations. Virgin 300 WM brass the first firing is to bump the shoulder close to 20/1000. I don't put that on paper nor chrono. I'll use those rounds to practice shooting technique. If you are shooting low pressure loads whether it's intentional or still working up to max pressure you aren't fully fire forming the brass.