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300 black out chambering issues using RCBS SB taper crimp


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I new to loading this round and using RCBS SB taper crimp die. 


Im following the directions to the T and I’m still getting issues gauging and chambering. 

 

When I load to 2.260 it is just barely out of spec in my gauge and when.I chamber it, it gets stuck. I have to slam the butt stock on the ground to get the bullet out. 


BUT if I keep seating the bullet farther in the case, it gauges and chambers fine. 2.240 is the sweet spot where it functions fine in my gun and gauge. WTF I’m pulling my hair out trying to figure out what’s going on. I’m using a 220 grain bullet and there’s zero difference on tbe bullet taper between these 2 depths. 


This is a 2 die set and the second die Seats and also puts a taper crimp on the bullet.


I load for 7 different calibers and nothing is as much of a pain in the ass as 300 black out. 

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Get this gauge with the side cut and you will find out where your issues are. If it gauges with the Sheridan it will run in a gun, unless of course the gun’s chamber is out of spec. 
 

I found my PSA barrels in 5.56 and 300 where milled to minimum spec.

 

https://sheridanengineering.com/product/300-blk-ammunition-gauge/

 

What could be happening is the neck is being deformed when seating bullet, or you have a barrel where the bullet hits the rifling sooner. 
 

 

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asking a question        at 2.260 fails gauge and WILL NOT CHAMBER.

                                      at 2.240 PASSES GAUGE and WILL CHAMBER.

    Why not load to 2.240 length.?

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Sounds like you’re engaging the rifling. If it were the crimp or neck thickness it would be a problem with the shorter ones also. Take a sharpie and color a long loaded bullet and then chamber it. You should be able to see rifling marks on the bullet when you extract it. Sometimes it’s faint but it doesn’t take much to stick one especially in an auto. 

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2 hours ago, dannyd said:

With me it was the neck thickness: turned the necks problem solved


What Danny said - I learned that if the brass I was using was converted LC brass it worked great but if it was other factory 223 or 5.56 brass that had been converted the wall thickness became an issue for me.  If it is factory 300 B/O brass the neck thickness should not be an issue. 
 

Over at the 300B/O forum they provide a list of the brass head stamps that will give you problems if the brass has been converted from 223 or 5.56….

 

Here is the link to the list of 223/5.56 head stamps that will or will not give you problems if they are cut down and converted to 300 B/O brass. Hopefully this will help….

 

https://www.300blktalk.com/forum/viewtopic.php?f=141&t=88599&sid=6fc6b05d8481f54774f46b69390d3c5d

 

Ask me how I know - I bought 1000 pieces of brass off of GB and it was a variety of mixed head stamps and over 200 would not gauge after loading and/or was hard as heck to get to go into my Ruger American rifle chamber and would get stuck in my AR…..

Edited by Sigarmsp226
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53 minutes ago, Sigarmsp226 said:


What Danny said - I learned that if the brass I was using was converted LC brass it worked great but if it was other factory 223 or 5.56 brass that had been converted the wall thickness became an issue for me.  If it is factory 300 B/O brass the neck thickness should not be an issue. 
 

Over at the 300B/O forum they provide a list of the brass head stamps that will give you problems if the brass has been converted from 223 or 5.56….

 

Here is the link to the list of 223/5.56 head stamps that will or will not give you problems if they are cut down and converted to 300 B/O brass. Hopefully this will help….

 

https://www.300blktalk.com/forum/viewtopic.php?f=141&t=88599&sid=6fc6b05d8481f54774f46b69390d3c5d

 

Ask me how I know - I bought 1000 pieces of brass off of GB and it was a variety of mixed head stamps and over 200 would not gauge after loading and/or was hard as heck to get to go into my Ruger American rifle chamber and would get stuck in my AR…..

Don’t own any AR’s but that Ruger American for me: definitely needs a better magazine.  Once I turned all the necks brass worked fine, but that’s my least favorite gun to shoot. ;)

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