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Instruct me on building a .300 Blackout...BARREL ARRIVED :-) EDIT...FINISHED IT UP... Login/Join 
Plowing straight ahead come what may
Picture of Bisleyblackhawk
posted
Maybe this should have been in the pistol section...but AR15s sorta seem like a rifle thing...building a .300 Blackout pistol upper has been on the back burner for awhile...but events as of late have thrust it forward somewhat...well pretty much front and center...

Keeping with that excellant advice to "buy what you need while it's quiet" from Para, over the last year I have purchased various and sundry AR parts when I find them at a good price (I'm "thrifty"...some will call it "cheap"...but I like "thrifty")...soooo...

I have the following (after pawing around in my big tub of AR parts) the following...

A new AERO upper...
A new AERO 7" M-LOK hand guard complete with propitary barrel nut and shims...
An AERO charging handle...
A new Toolcraft BCG...
An AERO SS pistol length gas tube...
A new low profile gas-block (w/ set screws) of unknown pedigree...but it looks GTG...

I ordered a 7.5" .300 Blackout stainless barrel from Bear Creek Arsenal today (it seemed like a "thrifty " purchase) so I figure it will be here in a week or three...

OK...where do I stand?

I still need a muzzle something (flash hider, KAK Flash Can, Flaming Porker, etc.)...what do you all recommend?...

I DO NOT plan on shooting this with a suppressor at this time (maybe never)...will it be over gassed for a standard carbine buffer (I hope to use my current pistol .556 lower if possible)...

Should I search for an adjustable gas block?...would a heavier buffer be needed? Should I wait to see how everything "works" before I try anything else?...should I ask the widow woman across the street for dinner and a movie (oops, that's another thread)...

I'm pretty good on .556/.223 ARs...but what do I need to know about building a .300 Blackout pistol length upper?...

Seriously...any input fom the great, experienced members of SIGForum will be appreciated Smile

This message has been edited. Last edited by: Bisleyblackhawk,


********************************************************

"we've gotta roll with the punches, learn to play all of our hunches
Making the best of what ever comes our way
Forget that blind ambition and learn to trust your intuition
Plowing straight ahead come what may
And theres a cowboy in the jungle"
Jimmy Buffet
 
Posts: 8267 | Location: Southeast Tennessee...not far above my homestate Georgia | Registered: March 10, 2010Reply With QuoteReport This Post
My hypocrisy goes only so far
Picture of GrumpyBiker
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Seriously it's just a barrel assembly difference from any 5.56.
Sounds like you're about ready to get it together.
I've built three that have been trouble free.
.43¢ per round is about the best I've found but I really enjoy this chambering.







U.S.M.C.
VFW-8054
III%

"Never let a Wishbone grow where a Backbone should be "



 
Posts: 5815 | Location: Central,Ohio | Registered: December 28, 2008Reply With QuoteReport This Post
For real?
Picture of Chowser
posted Hide Post
Check your feedramp. My 7.5” not stainless Bear Creek barrel would hang up on subsonic ammo.

A light touch with my (ducks behind couch) dremel, some qtips with flitz and it’s working just fine now.

Just waiting on my Sandman-K now.



Not sure what the weight is of the buffer in the PDW stock, but I've always used H2 buffers and had no issues suppressed or unsuppressed in my 8.25, 9, 10.5 300blk uppers.

I use an H2 in my 5.56 SBR and it works fine suppressed and unsuppressed too.



Not minority enough!
 
Posts: 5574 | Location: South of Cleveland, OH | Registered: August 09, 2007Reply With QuoteReport This Post
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Picture of GroundedCLK
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For buffer weight I am using Spikes Tactical T3, it help reduce perceived recoil and assisted with ejection patterns.
 
Posts: 1614 | Location: New Hampshire | Registered: January 12, 2005Reply With QuoteReport This Post
Prince of Cats
Picture of matthew03
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Sounds like you are good to go one the .300 Black, I love mine and run supers.

On the Widow Woman, get out there in the driveway and wash you car seductively and she'll be over to offer you dinner and a movie. Problem solved. Wink


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www.AppalachianConcealment.com
 
Posts: 6377 | Location: S.W. Virginia | Registered: March 18, 2011Reply With QuoteReport This Post
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posted Hide Post
quote:
Originally posted by GrumpyBiker:
Seriously it's just a barrel assembly difference from any 5.56.
Sounds like you're about ready to get it together.
I've built three that have been trouble free.
.43¢ per round is about the best I've found but I really enjoy this chambering.

.43 per rnd?
Where?



 
Posts: 261 | Location: midwest | Registered: May 29, 2007Reply With QuoteReport This Post
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quote:
Originally posted by dogrobber13:
.43 per rnd?
Where?

www.ammoseek.com
 
Posts: 5355 | Location: Colorado | Registered: January 26, 2008Reply With QuoteReport This Post
Plowing straight ahead come what may
Picture of Bisleyblackhawk
posted Hide Post
Well...I came home today and found that my barrel and .308 birdcage were on my front porch Big Grin...

I was a little bit concerned after reading some reviews on Bear Creek Arsenal barrels about fit and finish after the order was placed...but from what I can see, everything looks very good, feed ramps look well cut, smooth and polished...overall pretty pleased for the price...I will probably swap out the birdcage out later on for something else...

I just fit everything together to see how it will look and I think it will do...hopefully it will shoot well when I put it together later next week when I get my armorers wrench that will fit the AERO barrel nut back from being loaned out...I'm in no hurry...

Ammo prices locally are $21.99 per box and up...this will positively be a hand-loaded ammo proposition...

It will be handier than my 10.5" pistol...I think it will be a fun gun when finished...



********************************************************

"we've gotta roll with the punches, learn to play all of our hunches
Making the best of what ever comes our way
Forget that blind ambition and learn to trust your intuition
Plowing straight ahead come what may
And theres a cowboy in the jungle"
Jimmy Buffet
 
Posts: 8267 | Location: Southeast Tennessee...not far above my homestate Georgia | Registered: March 10, 2010Reply With QuoteReport This Post
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posted Hide Post
Try these guys for ammo

https://octanemunitions.com/pr...kout-220gr-subsonic/

I have a bunch and it's been good to go.

Bruce



Hanlon's Razor /prov./ A corollary of Finagle's Law, similar to Occam's Razor, that reads "Never attribute to malice that which can be adequately explained by stupidity."

“Once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return.”

--Leonardo da Vinci

 
Posts: 2668 | Location: NV | Registered: October 06, 2011Reply With QuoteReport This Post
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posted Hide Post
Does anyone know what kinds of velocity and muzzle energy to expect with the 7.5" barrel and supersonic ammo?
Ballistics by the inch hasn't tested 300 BO. I looked ;-)

Bruce



Hanlon's Razor /prov./ A corollary of Finagle's Law, similar to Occam's Razor, that reads "Never attribute to malice that which can be adequately explained by stupidity."

“Once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return.”

--Leonardo da Vinci

 
Posts: 2668 | Location: NV | Registered: October 06, 2011Reply With QuoteReport This Post
...and now here's Al
with the Weather.
Picture of guardianangel762
posted Hide Post
quote:
Originally posted by RNshooter:
Does anyone know what kinds of velocity and muzzle energy to expect with the 7.5" barrel and supersonic ammo?
Ballistics by the inch hasn't tested 300 BO. I looked ;-)

Bruce


2000 fps and about 950-1000 fpe at the muzzle.

My 8" does 2050 with Barnes 110 tac-tx


___________________________________________________
But then of course I might be a 13 year old girl who reads alot of gun magazines, so feel free to disregard anything I post.
 
Posts: 8970 | Location: Lake Stevens, WA | Registered: March 20, 2005Reply With QuoteReport This Post
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Wow!
That's almost double the ft lbs of energy of a 55 gr 5.56 from the same barrel length. Seems like a good choice.


Bruce



Hanlon's Razor /prov./ A corollary of Finagle's Law, similar to Occam's Razor, that reads "Never attribute to malice that which can be adequately explained by stupidity."

“Once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return.”

--Leonardo da Vinci

 
Posts: 2668 | Location: NV | Registered: October 06, 2011Reply With QuoteReport This Post
Prepared for the Worst, Providing the Best
Picture of 92fstech
posted Hide Post
I'm interested in building one of these myself, and possibly eventually SBR-ing it, if I end up liking the round. The .300 seems to be an ideal round for the shorter barrel...anybody have any idea what kind of muzzle blast to expect from a 7-8" barrel in .300 blackout?
 
Posts: 2780 | Location: In the Cornfields | Registered: May 25, 2006Reply With QuoteReport This Post
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posted Hide Post
quote:
Originally posted by guardianangel762:
quote:
Originally posted by RNshooter:
Does anyone know what kinds of velocity and muzzle energy to expect with the 7.5" barrel and supersonic ammo?
Ballistics by the inch hasn't tested 300 BO.

My 8" does 2050 with Barnes 110 tac-tx

There was a guy on arf.com who posted some good data on short barrel 300blk MVs, but the data is no longer visible after photobucket's policy change. 2050 with 110 grain sounds about right.

My 11.3" barrel produces 2,395 fps with Hornady Vmax 110 and 2,196 with Sig HPBT 125. Note that these figures are with a can, which for MV effectively makes the barrel about an inch longer.
 
Posts: 5355 | Location: Colorado | Registered: January 26, 2008Reply With QuoteReport This Post
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posted Hide Post
quote:
Originally posted by 92fstech:
anybody have any idea what kind of muzzle blast to expect from a 7-8" barrel in .300 blackout?

Short answer -- really unpleasant. Short barrels are loud.

I began my MV testing with a bare muzzle, as the Magnetospeed V3 works better without muzzle devices on the barrel. Wearing both plugs and muffs, it took only 2 or 3 rounds before I realized I will never shoot this 11.3" blackout upper again without a suppressor.

It took a little futzing to get the Magnetospeed to function while attached to a can. Furthermore, I had to wait quite a while between shots, so the can wouldn't heat up and melt the Magnetospeed's contact points. It was worth it.
 
Posts: 5355 | Location: Colorado | Registered: January 26, 2008Reply With QuoteReport This Post
Prepared for the Worst, Providing the Best
Picture of 92fstech
posted Hide Post
quote:
Originally posted by fritz:
quote:
Originally posted by 92fstech:
anybody have any idea what kind of muzzle blast to expect from a 7-8" barrel in .300 blackout?

Short answer -- really unpleasant. Short barrels are loud.

I began my MV testing with a bare muzzle, as the Magnetospeed V3 works better without muzzle devices on the barrel. Wearing both plugs and muffs, it took only 2 or 3 rounds before I realized I will never shoot this 11.3" blackout upper again without a suppressor.

It took a little futzing to get the Magnetospeed to function while attached to a can. Furthermore, I had to wait quite a while between shots, so the can wouldn't heat up and melt the Magnetospeed's contact points. It was worth it.


Thanks for the input. May be a better idea to SBR the 9mm, then.
 
Posts: 2780 | Location: In the Cornfields | Registered: May 25, 2006Reply With QuoteReport This Post
Go ahead punk, make my day
posted Hide Post
SBR rifles are meant to be suppressed, especially 300BLK.

While I have no problem tolerating SBR fire (as the shooter) with just electronic muffs, it's an easy way to clear the firing line of fools. Big Grin
 
Posts: 38199 | Registered: July 12, 2008Reply With QuoteReport This Post
Prince of Cats
Picture of matthew03
posted Hide Post
quote:
Originally posted by RHINOWSO:
SBR rifles are meant to be suppressed, especially 300BLK.

While I have no problem tolerating SBR fire (as the shooter) with just electronic muffs, it's an easy way to clear the firing line of fools. Big Grin


Last time I ran my .300 9" with supersonics, I was at the end of the firing line, indoors, against a cinderblock wall, I felt every shot. It was still fun


---------------------------------------
www.AppalachianConcealment.com
 
Posts: 6377 | Location: S.W. Virginia | Registered: March 18, 2011Reply With QuoteReport This Post
Plowing straight ahead come what may
Picture of Bisleyblackhawk
posted Hide Post
I finished the pistol up last week...only issue with the build was with the "new" gas block that I bought at our range "trade day" last year...it was not to spec...it would not fit the barrel (it would barely start when installing the right way, but reversing it...it wouldn't even come close. It's tapered Confused. So I ended up ordering one from Bear Creek Arsenal (the barrel manufacturer) and they had it to me in a couple of days and all was good (their gas block has 5 set screws, one to fit the dimpled barrel and 2 each at about the 4:00 and 8:00 position...it's pretty secure.)...

Picked up a box of 50 Magtech 123 grain .300BO for under $30.00...stuck an old TruGlo red dot on it that I've had forever and headed to the range...

It shot perfectly...10 rounds to get the red dot on a paper plate at 25 yards...then no issues at all through a full magazine...fed and extracted perfectly...

I did add a couple of Magpul .300 Blackout magazines to a Brownell's order to reach free shipping...I'm not sure if they are really necessary...but what the heck Smile

But boy is it loud!...



********************************************************

"we've gotta roll with the punches, learn to play all of our hunches
Making the best of what ever comes our way
Forget that blind ambition and learn to trust your intuition
Plowing straight ahead come what may
And theres a cowboy in the jungle"
Jimmy Buffet
 
Posts: 8267 | Location: Southeast Tennessee...not far above my homestate Georgia | Registered: March 10, 2010Reply With QuoteReport This Post
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Picture of Newf
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Looks good, congrats! FWIW shooting supers with my 10.5" barrel+brake, I don't find it that bad re muzzle blast, but then I'm old(er) and probably half deaf already Razz


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Canadian Coast Guard - Retired
 
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