Case forming

[GUNNTZ]

So, seems that 300 blackout brass is non-existent or super expensive; I've opted to make my own. Here is the problem, full seating dies will not bring 223/556 brass into the correct spec. I contacted lee and rcbs, they both say their dies are capable of forming but not really designed for it. When the brass is formed I get slightly out of spec results, basically the full seater will leaves the brass about 5 thousands out around the front neck area. Now my question is redding offers a trim die, but they say the neck must be turned or reamed. In my four years of reloading I've never come across this requirement. I know what the processes are, but what tools do I use??

[tiller]

So, seems that 300 blackout brass is non-existent or super expensive; I've opted to make my own. Here is the problem, full seating dies will not bring 223/556 brass into the correct spec. I contacted lee and rcbs, they both say their dies are capable of forming but not really designed for it. When the brass is formed I get slightly out of spec results, basically the full seater will leaves the brass about 5 thousands out around the front neck area. Now my question is redding offers a trim die, but they say the neck must be turned or reamed. In my four years of reloading I've never come across this requirement. I know what the processes are, but what tools do I use??

Form with a standard die, fire and you have formed brass!!!

Problem solved... Dont over think things

[GUNNTZ]

There's no over thinking going on. My current issue is that the formed brass is out of spec, it's unusually tight in the chamber of my rifle. When dropped in the go-no-go guage, it's clearly out of spec. I would prefer not to have my investment get damaged from being complacent and careless.

[FLIGHT762]

You didn't say what brass you are using for your conversion. It seems certain makes of brass have thicker case bodies and cause necks to be too thick.

Here's a couple of discussions on the subject:

http://www.handloadersbench.com/forum5/27238.html

http://forum.snipershide.com/snipers-hide-reloading/196193-resizing-5-56-lc-brass-300-blackout-experiences.html

[GUNNTZ]

I'm using lake city 5.56 that was once fired out of my AR primarily. I tried some 223 federal brass with very similar results.

[tiller]

I'm using lake city 5.56 that was once fired out of my AR primarily. I tried some 223 federal brass with very similar results.

Ive formed over 1200 rounds in the standard full length die with no problems what so ever... They all fired perfect and formed perfect to my chamber ready for resizing!

[GUNNTZ]

Found the issue, de-primer/neck sizer. For some reason it was interfering with the neck formation. Pulled it out, formed and the re-installed the rod. Now in perfect saami spec. I'm using Lee dies, so whoever uses their dies might need to follow the same steps.

Tiller: my issue wasn't that they didn't form, its that they were way to tight in the chamber on extraction. This is a perfect setup for overpressure or out of battery firing if it didn't chamber quite right. It's always better to be to cautious than not enough. I like my guns, hands and face way to much...