300 Blackout brass

[1lessdog]

I bought some of the Top brass 300 BL made from 223. Just wondering if anyone else is running this stuff. Only 1 out of 10 will chamber in my Rifle and SBR.

 

[Hoser]

Did you full length resize it and bump the shoulder back to fit your rifle?

 

[1lessdog]

No I didnt, most preped brass should chamber, Im assuming that is what they do when they size it, I guess not.

 

[Bill K]

Most of the brass made from formed and cut down .223 brass, needs prepped by FL sizing in your cartridge's die, trim and maybe even neck turned, chamfered and then loaded for the final forming into your chamber.

 

[Hoser]

There is a ton of different 300 chambers out there. Everything from 300 Hush to 30-221 to 300 Blackout.

If they set the shoulders long and let the reloader set the final dimension, they dont overwork the brass.

 

[1lessdog]

I have loaded shells for 40 yrs and have never had to resize new or once fired brass that has been prepped already. And the 300 Blackout is the only round I have ever had this problem with.

I got a email from Top brass stating they do full length resize and should not have to resize once more. I will run them thru a small base resizer and see how they chamber.

 

[dellet]

I have loaded shells for 40 yrs and have never had to resize new or once fired brass that has been prepped already. And the 300 Blackout is the only round I have ever had this problem with.

I got a email from Top brass stating they do full length resize and should not have to resize once more. I will run them thru a small base resizer and see how they chamber.

How much of the brass you have bought and worked with over the years was converted military, probably full auto fired from an over-gassed, over pressured half clapped out rifle?

Wondering if this is a new load, or just new brass?

Might be worth checking loaded neck diameter, and bullet hitting the lands.

 

[Uncle Ed]

I have loaded shells for 40 yrs and have never had to resize new or once fired brass that has been prepped already. And the 300 Blackout is the only round I have ever had this problem with.

I got a email from Top brass stating they do full length resize and should not have to resize once more. I will run them thru a small base resizer and see how they chamber.

Color a few cases with a felt tip marker then chamber them and see where they are rubbing. You may be able to get by with just sizing them again and bumping the shoulders back a smidgen. You just might be dealing with thicker brass and spring back after the factory sizing.

 

[dantiff2]

Use a case gauge such as the Hornady model. These little black-outs can be finicky. I choose to small base size all of mine. I've run Top Brass but make 99% of mine from other brass that I have acquired. Top brass uses Lake City 5.56 military range pickup. If you try them right out of the bag you will see that most do NOT fit a gauge. I'm not sure what sizer die they use but it's out of spec! Besides that. most of the brass in the bag have really beat up necks so you should want to rerun them through a die just for that reason alone.

https://www.brownells.com/reloading...0-aac-blackout-cartridge-gauge-prod99057.aspx

 

[kindabitey]

FWIW, all of the converted 300blk brass I have purchased had to be sized. Mostly because the shoulder wasn't back far enough. You should probably anneal it, as well. I'm fairly certain
most of the folks converting it from 223/5.56 don't anneal before sizing.

 

[Hoser]

FWIW, all of the converted 300blk brass I have purchased had to be sized. Mostly because the shoulder wasn't back far enough. You should probably anneal it, as well. I'm fairly certain
most of the folks converting it from 223/5.56 don't anneal before sizing.

If it is once fired, it really does not need to be annealed. There is plenty of the factory anneal left in the neck and shoulder area. When people ask me to process 300 for them, I dont normally anneal unless they really want it. None of my full auto ammo gets annealed and it does just fine. One thing I have started doing all the time is roll sizing 300 brass as the last step to be sure the base of the case gauges fine.

I have been shooting the 300 for 10+ years and have converted many thousands of pcs of 223 into 300. I have also formed 221 fireball into 300 and even formed 357 Max into 300 Rimmed Whisper for TC Contenders. I have always left the shoulder long to allow people to set it to their chamber, For the longest time the 300 Whisper and all its flavors was a wildcat round. It was not until AAC got involved that a SAAMI spec happened. In fact, some of the first 300 Whisper chambers were cut with a 1.400 case length in mind. This is a no-go in todays Blackout chambers.

 

[LVLAaron]

Size them. Trim/chamfer/debur as well. The converted top brass I've seen at Cabelas looks like they did it with a chainsaw.

 

[Hino895]

Size them without the expander ball in place.
It’s easy to pull the shoulder out with the ball in place.
Use a universal decapping die to deprime.
This works for me.