5.56 into a 300 blk chamber???

[ponzer04]

Will a 5.56 fit into a 300 blk chamber? what would happen? I have not gotten my 300blk rifle yet and i have now seen more than one post where ppl have done the opposite and blew guns up. I'm just curious if they will fit?

[rancilio]

Nope, the 5.56 (or .223) is just a bit longer. Check out the saami site, click rifle, then click a name to get the drawings.

http://www.saami.org/specifications_and ... fm?page=CC

.223 is ~1.44in to shoulder and ~2.125-2.260in OAL while 300 Blk is is ~1.07in to shoulder and ~1.78-2.260in OAL.


"Will a 5.56 fit into a 300 blk chamber? what would happen? I have not gotten my 300blk rifle yet and i have now seen more than one post where ppl have done the opposite and blew guns up. I'm just curious if they will fit?"

[Wo0dzm3n]

Search the topic 300 n 223

[Swat50]

I know this is a old topic but FWIW I deprime and size my 300 brass in a 223 sizer die. has worked well for me so far. so it will fit.

I am sure someone will let me know if they object, umm for safety reasons or what ever.

I should say I have a progressive press and no spare dies for 300, so this works best for me.

[Sharkbite]

I know this is a old topic but FWIW I deprime and size my 300 brass in a 223 sizer die. has worked well for me so far. so it will fit.

I am sure someone will let me know if they object, umm for safety reasons or what ever.

I should say I have a progressive press and no spare dies for 300, so this works best for me.

The OP asked if it would fit in a CHAMBER not a reloading die.

[Swat50]

I know this is a old topic but FWIW I deprime and size my 300 brass in a 223 sizer die. has worked well for me so far. so it will fit.

I am sure someone will let me know if they object, umm for safety reasons or what ever.

I should say I have a progressive press and no spare dies for 300, so this works best for me.

The OP asked if it would fit in a CHAMBER not a reloading die.

I assumed they were the same size, or close.

[dellet]

I know this is a old topic but FWIW I deprime and size my 300 brass in a 223 sizer die. has worked well for me so far. so it will fit.

I am sure someone will let me know if they object, umm for safety reasons or what ever.

I should say I have a progressive press and no spare dies for 300, so this works best for me.

I don't object, but if I understand correctly, you don't have a 300 sizing die? Or you size it twice?

The problem with only using the 223 die is that you are not sizing the neck and shoulder. Sooner or later you will have feeding problems and if you mix brass and chambers, you will have a headspace issue.

The 300 will fit into a 223/556 chamber as long as the bullet will push back into the case allowing the bolt or action to close. The round will seat on the bullet instead of the shoulder.

The 223/556 round can not chamber into the 300 unless you force it hard enough to use the chamber as a forming die.

[Swat50]

I know this is a old topic but FWIW I deprime and size my 300 brass in a 223 sizer die. has worked well for me so far. so it will fit.

I am sure someone will let me know if they object, umm for safety reasons or what ever.

I should say I have a progressive press and no spare dies for 300, so this works best for me.

I don't object, but if I understand correctly, you don't have a 300 sizing die? Or you size it twice? yes twice

The problem with only using the 223 die is that you are not sizing the neck and shoulder. Sooner or later you will have feeding problems and if you mix brass and chambers, you will have a headspace issue.

The 300 will fit into a 223/556 chamber as long as the bullet will push back into the case allowing the bolt or action to close. The round will seat on the bullet instead of the shoulder.

The 223/556 round can not chamber into the 300 unless you force it hard enough to use the chamber as a forming die.

thank you for the clarification

[Jmorrismetal]

I know this is a old topic but FWIW I deprime and size my 300 brass in a 223 sizer die. has worked well for me so far. so it will fit.

I think the ops question would be more like sizing your .223 brass in a 300 die. He already knows the 300 will chamber in a 223.

[tXr]

223/556 will not fit in a 300blk chamber it is far too long. That is why you can take 223/556 brass and form it shorter to create 300blk. I suppose you could try and chamber a round, but you will then be using the chamber as a forming die, the powder and bullet will prevent that from occurring and you will need to mortar the rifle to extract the round(hopefully).