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A few 300 Blackout questions....

Posted: Sat Dec 21, 2019 6:19 am
by KMPLSV
A few questions from a newb...

If I build a 300 Blackout AR-15 pistol can I safely shoot .223 and 5.56 with a simple barrel change or do I need an entirely separate .223/5.56 upper?

I realize that this next question depends on your application/requirements. My main requirement is to be accurate out to 100 yards. I plan on using a plain red-dot. Nothing too insane. That being said; what would be the optimal barrel length for this setup in your opinion? I'm looking at 7", "7.5, 9", and 10". I'm attracted to the 7" and 7.5" mainly just for fun. Here are a few points I've seen mentioned frequently along with a couple more questions I have...

1. The 300 Blackout reaches peak ballistic potential from a 9-inch barrel.

2. A 10-inch barrel on an AR pistol or a short barreled rifle is perfect for the 300 Blackout.

3. I'm not entirely certain that I'll want to go with a suppressor in the end. Will a 300 Blackout pistol that is not suppressed and has a 7" barrel raise absolute hell in the loudness department? I've heard both sides of this argument. How much difference is there in loudness between an unsuppressed 300 Blackout pistol in 7" and one in 9" or 10"? When you're shooting unsuppressed does using subsonic ammo make a difference? At what barrel length, if any, would you say, that the pistol should absolutely be suppressed? Does running them unsuppressed mean they'd be out of the question for home defense? Do you think that the loudness of the initial round would render you so dazed and out of it that you'd be unable to eliminate a threat?

I appreciate any help. I realize I wrote a book here. I just want to have the proper knowledge before I pull the trigger for my first build.

Re: A few 300 Blackout questions....

Posted: Sat Dec 21, 2019 12:41 pm
by dellet
KMPLSV wrote:
Sat Dec 21, 2019 6:19 am
A few questions from a newb...

If I build a 300 Blackout AR-15 pistol can I safely shoot .223 and 5.56 with a simple barrel change or do I need an entirely separate .223/5.56 upper? . In theory, yes. Plan on a couple hours and some range time to get it sighted in everytime you make the switch..

I realize that this next question depends on your application/requirements. My main requirement is to be accurate out to 100 yards. I plan on using a plain red-dot. Nothing too insane. That being said; what would be the optimal barrel length for this setup in your opinion? I'm looking at 7", "7.5, 9", and 10". I'm attracted to the 7" and 7.5" mainly just for fun. Here are a few points I've seen mentioned frequently along with a couple more questions I have...
First ypou need to define "accuracy". from what you describe sounds like like 2MOA is all you expect, and barrel length won;t be the limiting factor

1. The 300 Blackout reaches peak ballistic potential from a 9-inch barrel.This is a completely false statement

2. A 10-inch barrel on an AR pistol or a short barreled rifle is perfect for the 300 Blackout.This one is worse than the last one. Maybe in a narrow use.

3. I'm not entirely certain that I'll want to go with a suppressor in the end. Will a 300 Blackout pistol that is not suppressed and has a 7" barrel raise absolute hell in the loudness department?yes

I've heard both sides of this argument. How much difference is there in loudness between an unsuppressed 300 Blackout pistol in 7" and one in 9" or 10"?Not enough to make a difference in hearing saftey

When you're shooting unsuppressed does using subsonic ammo make a difference?not really, it's just a different tone

At what barrel length, if any, would you say, that the pistol should absolutely be suppressed?depends on your hearing protection

Does running them unsuppressed mean they'd be out of the question for home defense?Not if you would use any other non-suppressed firearm

Do you think that the loudness of the initial round would render you so dazed and out of it that you'd be unable to eliminate a threat? No, but if it's in the dark, the fire ball will leave you blind

I appreciate any help. I realize I wrote a book here. I just want to have the proper knowledge before I pull the trigger for my first build.
Probably going to need to define your goals a bit better. It appears that you've been reading a whole bunch of stuff from people that don't have a clue and that explains the confusion.

Re: A few 300 Blackout questions....

Posted: Sat Dec 21, 2019 1:23 pm
by Sig220
My only comment so far...........

Given the choice of changing barrels or changing uppers to change calibers, I would pick changing uppers every time.

It is easier, quicker and could already be sighted in. A little more expensive for the other parts, but easily outweighed by the other advantages.

Re: A few 300 Blackout questions....

Posted: Sat Dec 21, 2019 2:01 pm
by gds
dellet wrote:
Sat Dec 21, 2019 12:41 pm
KMPLSV wrote:
Sat Dec 21, 2019 6:19 am
A few questions from a newb...

If I build a 300 Blackout AR-15 pistol can I safely shoot .223 and 5.56 with a simple barrel change or do I need an entirely separate .223/5.56 upper? . In theory, yes. Plan on a couple hours and some range time to get it sighted in everytime you make the switch..

I realize that this next question depends on your application/requirements. My main requirement is to be accurate out to 100 yards. I plan on using a plain red-dot. Nothing too insane. That being said; what would be the optimal barrel length for this setup in your opinion? I'm looking at 7", "7.5, 9", and 10". I'm attracted to the 7" and 7.5" mainly just for fun. Here are a few points I've seen mentioned frequently along with a couple more questions I have...
First ypou need to define "accuracy". from what you describe sounds like like 2MOA is all you expect, and barrel length won;t be the limiting factor

1. The 300 Blackout reaches peak ballistic potential from a 9-inch barrel.This is a completely false statement

2. A 10-inch barrel on an AR pistol or a short barreled rifle is perfect for the 300 Blackout.This one is worse than the last one. Maybe in a narrow use.

3. I'm not entirely certain that I'll want to go with a suppressor in the end. Will a 300 Blackout pistol that is not suppressed and has a 7" barrel raise absolute hell in the loudness department?yes

I've heard both sides of this argument. How much difference is there in loudness between an unsuppressed 300 Blackout pistol in 7" and one in 9" or 10"?Not enough to make a difference in hearing saftey

When you're shooting unsuppressed does using subsonic ammo make a difference?not really, it's just a different tone

At what barrel length, if any, would you say, that the pistol should absolutely be suppressed?depends on your hearing protection

Does running them unsuppressed mean they'd be out of the question for home defense?Not if you would use any other non-suppressed firearm

Do you think that the loudness of the initial round would render you so dazed and out of it that you'd be unable to eliminate a threat? No, but if it's in the dark, the fire ball will leave you blind

I appreciate any help. I realize I wrote a book here. I just want to have the proper knowledge before I pull the trigger for my first build.
Probably going to need to define your goals a bit better. It appears that you've been reading a whole bunch of stuff from people that don't have a clue and that explains the confusion.
As usual Dellet said what I was thinking, but just in a nicer way. :lol:

Re: A few 300 Blackout questions....

Posted: Sun Dec 22, 2019 8:52 am
by KMPLSV
Thank you all so far for the feedback. I appreciate you debunking some of the crap info I gathered up. I've learned a lot just in the past few days. I think I'll be going with the 7.5" barrel initially and getting something like the Noveske Flash Hider KX3 Pig. After that I can build a 5.56 upper and switch out the upper as desired.

Re: A few 300 Blackout questions....

Posted: Wed Dec 25, 2019 8:08 pm
by Firewalker41
I use a BRT comp. A flash fowarder. It simply redirects the noise and blast down range. It has a much smaller profile than the Flaming pig.
Either one is necessary to protect from noise and concussion, I use mine on a 7 1/2 inch BO. It is useful for deer to just shy of 200 yrds with 110 barnes, and 115 gr CC. We have harvested 5 deer with this rig with no losses and minimal tracking.

Re: A few 300 Blackout questions....

Posted: Mon Feb 10, 2020 7:17 pm
by BMG1976
Sig220 wrote:
Sat Dec 21, 2019 1:23 pm
My only comment so far...........

Given the choice of changing barrels or changing uppers to change calibers, I would pick changing uppers every time.

It is easier, quicker and could already be sighted in. A little more expensive for the other parts, but easily outweighed by the other advantages.
^^ this why have to re zero every time? convenience easily outweighs cost here

Re: A few 300 Blackout questions....

Posted: Mon Feb 24, 2020 5:40 pm
by rebel
Yes that is why you have to re zero, plus I am tired of the current top post that makes me puke.