Discussion: .300 Blackout 220gr Hornady Interlock

Member 5605 · Apr 16, 2019

saxon said:
yes safe as far as length
hornady 308 220. Round Nose 1.283
sierra 308 220. Round Nose 1.303
so will be within the ball park on COAL
the hornady having .020 less bullet in the cartrige if seated to sierra COAL

You can get a good idea of max cartridge length without any special tools.

If you take the expander out of your sizing die and size a case this will have a neck opening around .302". Insert a bullet upside down in the case and measure. Use this as a starting COAL to make a dummy round.

If you pull the bolt and insert the now made dummy into the chamber with finger pressure, it should stick because it will be jamming into the lands. Bump the length down a few thousandths at a time until the round drops out of the chamber under it's own weight. Somewhere between the last length it stuck and fell out is max length.

If what you have already made up will do that, great. But if not you will want to shorten them.

hear is a neat link for playing with mix and match bullets and knowing bullet lengths

JBM - Bullet Length List

that way when you mix and match you can be safer in your COAL I.E.
don't load a
speer 308 150. Mag-Tip SP .965 to a COAL meant for
hrn 308 150. Spire Point @ 1.064

Well I just found that....

2.000" doesn't feed from the rifle. It binds up in the start of the barrel.

2.183" (max mag) does feed.

I have a few I need to lengthen tomorrow before testing

11.0gr, 10.6gr, 10.2gr, 9.8gr
IMR 4227
CCI SRP

Member 5605 · Apr 20, 2019

Dyjital said:
11.0gr,
10.6gr,
10.2gr,
9.8gr
10.2gr CRIMPED
IMR 4227
CCI SRP

By ear today I tested these. No supersonic crack. The suppressor sure has a distinct thump and psssstfwhoop sound. Lol.

Looking forward to running them through the chrono.

On another note, I found a good way to hold the brass while I trim it in the Frankford Arsenal trimmer.

bobdog308 · Apr 20, 2019

What is the point of the 300 blackout, the ballistics suck. Oh please enlighten me

American123 · Apr 20, 2019

bobdog308 said:
What is the point of the 300 blackout, the ballistics suck. Oh please enlighten me

Is this satire?

Edit to say:

Some people are really into suppressors, it does it better than the .223 does.

Some people are into short barreled rifles / pistols.

Comparing super Sonics

110gr .300 BO vs 55-62gr .223

If interested in energy imparted on / into target, with shorter barrels the .300 outshines the .223 in that role as the .223 projective relies heavily on velocity to be effective, when the barrel length drops, velocity does with it. Firing a projectile double the weight a little slower (.300 BO) makes sense.

Some people like the 7.62 x 39, and the AR but that was never really done well or cost effective in an AR platform. The .300 BO gets pretty close.