Lead Bullets in Polygonal Bore?

[eddie56]

I no its said not to run cast bullets in an AR15 but I'm a die hard caster.I have also been told not to run cast in a polygonal rifle bore.What do you think?I would really like to give it a try.But figured I better ask people that know more than myself before I get into a mess.Thanks for any help you may have.

[texcl]

I think the bigger problem is twist rate and leading of the gas system. polyagonal rifling has been around since the black powder era where all bullets were lead.

[dr69er]

Typically cast lead rounds don't work well in a poly gassed rifle barrel like
in the AR-15 platform with direct gas impingment.

Chances are you will lead-up the gas tube (and other parts)
after a while, even when using gas checks on the bases of
your projectiles when driving projectiles at typical rifle
speeds.

Although, that does not mean you can't give It a try with hard
cast projectiles and using gas checks etc.

I only have had experience with cast lead in pistol calibers though....

Good Luck. YMMV.

Perhaps Carl or Ritch can chime with their experience on the
subject at hand with a more definitive answer...

[m4weave]

Although I cannot state from personal experience and it is not specific to the 5.56, I have read of those who successfully use heavy cast projectiles for their 300 blackout builds. Though, I am not sure if I read about that for conventional rifling or poly...

Sorry I cannot help more, though I am interested if you do venture into lead bullets for the 5.56.

Regards,
-Mike

[GLSHOOTER]

I think getting the pressure up will be an issue with lead in the poly rifling. The usable velocites will be pretty low. Better a 22 Mag than the 223 platform IMHO.

Greg