New member, have a M1S .300 Fireball barrel - now what?

[sharky47]

Hello, my name is Dan - first post but have been lurking for some time. Been trying to register but up until lately, the "Nospam!" feature had been keeping me from completing the form.....

Anyway, I am a CNC machinist from Central Texas and I am right in the middle of putting together a .300 whisper upper for an AR-15 pattern rifle. I have built countless AR's, some exotic requiring serious machine work - and I have been reloading for many calibers and loving it!

Ok, so I ordered a 16" 1-8 twist barrel from M1S, I ordered it WITHOUT a gas port so that I could put it wherever I wanted it and make it whatever diameter I wanted it. This rifle is going to be dedicated to shooting long/heavy bullets at subsonic speeds only. Unless there is a glaring reason I shouldn't, I am planning on putting the port in the pistol position like my friend's Noveske barrel.

One thing I have yet to get a real clear idea on is the cartridge dimensions. I will be making my own brass out of .223 and want to get the lowdown on lengths for the .300/221 chamber that M1S sells.

The last thing is some good subsonic load for 200+ grain bullets. I prefer Hogdon powders, but will use something else if it's known to work well.


Cheers!