Troubleshooting .300 Blackout reloads

[.308LiteHunter]

So I made a bunch of reloads and had some issues out at the range. Some would fire and some wouldn't chamber.

I just received my Sheridan 300 Blk slot gauge for checking the reloads.

I sorted the good from bad and then proceeded to pull the bullets from the bad reloads.

I then resized the brass again and checked it in the new Sheridan gauge. Good to go.

Now here is where I'm having an issue. The brass fits fine in the gauge but as soon as I load a bullet they stop fitting in the gauge. They barely stick out of the bottom of the gauge which means they are a no go.

I'm using Lee dies, and the reloads are one of 98's recipes for Hornady 150fmj.

[AngelDeVille]

Are your case lengths uniform? How are you crimping?

[.308LiteHunter]

Case lengths aren't perfect but they are all real close.

I thought about the crimping, because I was checking them before the crimp.

I put just a light crimp on them but still no go.

[AngelDeVille]

Next, are these converted .223 cases or BLK headstamp?

And, Are all cases same headstamp?

Edited May 10, 2015 by AngelDeVille

[.308LiteHunter]

All converted PMC .223 cases.

[AngelDeVille]

Only things I can think of is some cases are too long and are getting a heavier crimp.

Or your die wasn't adjusted properly and some cases didn't full size.

Are you trimming from oal or from the shoulder?

[.308LiteHunter]

Well, remember the brass was good to go before loading the bullets.

And they wouldn't fit the gauge properly even before crimping.

The brass was trimmed with a Lee case length gauge, which I know are cheap but they have worked well with other calibers for me.

[buzziebells]

If this is converted brass, case neck wall thickness is most likely the problem.  Without the projectile in the case, the neck is not expanded, so it fits in the gauge, after seating the projectile, the neck is expanded past the point of chambering due to too thick brass.  Go to 300blktlk.com and check out "Brass, the good, the bad and the ugly."  LC brass is always good to go.  Some of the others, not so much.

[.308LiteHunter]

^^^^

I remember reading about that

I used the PMC because I didn't have a swagger for the LC brass. I've got one now so I'll convert some and see if that works.

Thanks for the reminder about the neck wall thickness.

[392heminut]

If this is converted brass, case neck wall thickness is most likely the problem.  Without the projectile in the case, the neck is not expanded, so it fits in the gauge, after seating the projectile, the neck is expanded past the point of chambering due to too thick brass.  Go to 300blktlk.com and check out "Brass, the good, the bad and the ugly."  LC brass is always good to go.  Some of the others, not so much.

^^^^^THAT right there! <thumbsup>

[sketch]

I think I hade the same problem I have mixed brass! Guess I'll be sorting brass tomorrow.

[98Z5V]

If I ever get chambering issues with a certain batch of 300 reloads, I always look at the headstamp on the brass.  I won't use Federal at all, stopped using PRVI because the bases would expand after two reloads.  I've had some PMC that was tough to chamber, and it was the wall thickness on the mouth (new location, now, after cutting down).  Overall, the PMC brass is good brass.

 

It only happened on 6 or 8 of them.  Pulled the decapping rod out of the sizer die, and made one pass with them.  Problem solved.

 

For 300BLK, the only brass I'll use anymore is Lake City.  I don't have any issues loading the LC brass, it's more consistant, and it's lasting longer. 

[survivalshop]

 I've used nothing but , RP 300BLK or LC MilSpec Brass & never had a problem . Good to know about the different neck thickness , there's a tool to take care of that, if you want to spend the extra time to turn the necks.

 

  It was already mentioned , but some times even a slight crimp , can bulge the shoulder on a 5.56 case . Best way to tell is , if you have a Dial Caliper or a Micrometer , measure at end shoulder , before it slops into the neck ,before seating the bullet , then after you Crimp it . You can take the same Measurement after seating the Bullet if you think seating the bullet may be setting the shoulder back & it doesn't take much , to keep the cartridge from chambering.

   You can also measure the Case neck Diameter before & after seating the Bullet , to see how much it changes & take a measurement of a know good chambering Cartridge to see if they is a difference .

 

   What fun <thumbsup>

[98Z5V]

^^^ I've had that happen, too, on "new" cut down brass.  After I've fired it for the first time (fire-formed it), I haven't had it happen.

 

If you set your die up wrong, you can CREATE that situation.  Found that out when I first started making my own brass...  :banana:

[AngelDeVille]

I set up my cutoff saw for very minimal triming after forming. I use those cheap Lee trimmers, and they tend to be slightly under spec. 

 

And the Lee factory crimp dies are great.

 

I prefer OAL trimming to shoulder trimming

 

My first batch of 100 that I shot on Sunday went extremely smooth after the first 5-10 rounds on a new build.