.300 Blackout build discussion (formerly known as .300 Blackout barrel question...which was never answered anyway)

(So as not to have you guys write your build discussions over in another thread, I just changed the title of this one to make it easier.  It's what I do.  You're welcome.)

LF has a history....and a glorious one I might add...of a single event or person instantly making an item rise to celebrity status.   The RAID pack, P-Mags, MultiCam, LT mounts, etc. are but a few of the examples.  (I should know as I fell for all four.)

Now with AARs trickling out of Hogpocalypse 2019,  .300 Blackout, while remaining steadily popular since its introduction, now arises to the forefront in the categories of "best piggy popper" and  "truck gun."  So let everyone know what you guys are leaning towards and why.  I'll still be searching for my freaking barrel over here in the corner.

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IT'S A COLT.  THEY'RE LIKE THE HK OF GUNS.

HRH (Ret.) The Most Reverend Consig

Stupidity is not a skillset.

 

 

 

 

 Joined: 28 Nov 2004: 0037hrs        Location: The worst run state in the U.S

Original Post

You can run and adjustable gas block and a pigtail gas tube to give the same dwell time and psi curve of the longer bbl/gas system.

It's what I'm doing for mine.568597RRPH5PIGTAIL

Location: in SE Idaho, the birthplace of television. 

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Can you do a pistol build? Can you legally purchase suppressors in CT?

Because if you can't do a pistol length bbl, 8.5 to 10.5 can you have JoJo's or one of their Confederates perm attach a suppressor with  user serviceable internals? That would give you a short barrel and a can but only need one tax stamp. The 300blk was designed around a 9in bbl. With a pigtail and permanently attached hearing protection device you have a soft shooting,easy to point carbine.

I've shot this set up and it was neat enough to have me start (slowly) getting one. Hogpocalypse has bumped it into high gear.

Location: in SE Idaho, the birthplace of television. 

No problem with either.  Just easy to buy a LT SUURG upper and be done with it.

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IT'S A COLT.  THEY'RE LIKE THE HK OF GUNS.

HRH (Ret.) The Most Reverend Consig

Stupidity is not a skillset.

 

 

 

 

 Joined: 28 Nov 2004: 0037hrs        Location: The worst run state in the U.S

Maybe a new thread "Post your .300 BO build here" is in order.  I believe there there are more than a few of us on the same quest.

I'd do it but not sure which sub-forum it belongs in as some will be pistol builds and others rifle/carbine.

I too am working on this and have been in contact with M.W and tracking a similar path, but still undecided on the final product and how to go about it.

k

Joined: 7/15/04 8:49 AM
Location: Northern Nevada

I'm doing a pistol build to be able to make the most of the fact the round was designed for a 9" barrel and with a nice quiet can, I'm still shorter than a regular carbine which makes it easier to maneuver without the penalty of a 5.56 and a short barrel. Oh and I get a .30 Cal freedom pill dispenser.

With a pistol, I can also carry it loaded in my vehicle, take it hunting with a bow (because bears, wolves and Mt. Lions) and I don't have to ask permission to cross state lines with it.

If SBR'ing wasn't such a pain in the prostate I'd do that, but still wouldn't be able to carry it loaded in my car or hunting in any season but rifle hunting season. 

Watching Travis Haley ring steel over 900yds with his was damned impressive, but that guys a cyborg sent back in time...

Location: in SE Idaho, the birthplace of television. 

I've been slowly working on a "budget" 300 BO pistol build.

It's running, but barely scratching the surface of broke in, so no comments on reliability yet. 

It's minute of COM dirtbag accurate at 100m with irons, so that's good for the purpose of this build. 

As soon as I finish wringing it out I'll make a post of what I have encountered and the why-fors, how-comes, and oh-shit I have encountered.  My last two decision points are RDS and WML.

I know the LF standard for RDS is the Aimpoint. However... That's not happening on this build. I have been seriously looking at (as much as it pains me to admit) the Vortex and Holosun RDS units. 

Dave

------------------------------------- "A True Warrior knows neither Left or Right"  Looking for a doc who can fix my allergies.. Stupid People and IED's...

I have two .300Blk guns, I was going to suppress them but haven’t stepped off into NFAland.  

One has a 16” carbine gassed DD barrel,  DSG BCG, ALG ACT trigger,  1-4x Vortex Crossfire (?) scope.  Functions 100% with supers, 80% with subs (240gr cast @ 950fps sounds like a .22lr) sub 1” groups at 100 yards with 125SST @ 2,200FPS.  Kills deer quite well.

The second one is an 8” Palmetto upper,  Palmetto lower with a mishmash of parts, SB brace and an old Burris Fast Fire rds.  It hasn’t choked on anything I’ve fed it, puts supers into an inch at 50 yards.  It’s a Toy Grade gun but fun to shoot, I intend to put together something a bit more serious in the future. 

David Reeves, I picked up a SIG Romeo 5 last month from Palmetto State Armory and so far I’m impressed with it compared to my H-1.   It probably comes from the same factory as Holosun and/or Primary Arms stuff.

While I understand AR pistol builds fit some people's needs/laws,  we call them AIDS Cannons here in the formerly had a Constitution State.  Not for me with our restrictions although some people use them as noise makers at the range.

MW, I had forgotten about the pig tail so thank you for that.  Is there ever a clearance issue under a rail?  I'm guessing they've thought of that so probably not.

I am in zero hurry and still have the 6.8 for now although it is for sale.

-------------------------

IT'S A COLT.  THEY'RE LIKE THE HK OF GUNS.

HRH (Ret.) The Most Reverend Consig

Stupidity is not a skillset.

 

 

 

 

 Joined: 28 Nov 2004: 0037hrs        Location: The worst run state in the U.S

Rick R2 posted:

I have two .300Blk guns, I was going to suppress them but haven’t stepped off into NFAland.  

One has a 16” carbine gassed DD barrel,  DSG BCG, ALG ACT trigger,  1-4x Vortex Crossfire (?) scope.  Functions 100% with supers, 80% with subs (240gr cast @ 950fps sounds like a .22lr) sub 1” groups at 100 yards with 125SST @ 2,200FPS.  Kills deer quite well.

The second one is an 8” Palmetto upper,  Palmetto lower with a mishmash of parts, SB brace and an old Burris Fast Fire rds.  It hasn’t choked on anything I’ve fed it, puts supers into an inch at 50 yards.  It’s a Toy Grade gun but fun to shoot, I intend to put together something a bit more serious in the future. 

David Reeves, I picked up a SIG Romeo 5 last month from Palmetto State Armory and so far I’m impressed with it compared to my H-1.   It probably comes from the same factory as Holosun and/or Primary Arms stuff.

I deeply regret not snatching up a handful of the Steiner R1X  when they were stupid cheap a couple months ago.. 199.00 should have been my trigger to pick up several... But my mind (and wallet) were elsewhere at the time.

I've been looking at the Sig a bit, I'm just a little leery after reading reviews and putting my hands on one.  I keep mentally saying "it doesn't look / feel like a T1.." but it doesn't cost what a T1 does either. 

------------------------------------- "A True Warrior knows neither Left or Right"  Looking for a doc who can fix my allergies.. Stupid People and IED's...

I have some astigmatism for which I have been unsuccessful in getting lenses that are a complete correction.  So I am interested in the Primary Arms Cyclops optic.  It is a bit bigger than an Aimpoint Micro, uses the same mounts, and is a 1x prism scope.  Not a red dot.  ACSS reticle with illumination.  The reviews have been all positive and I'm planning to get one.  I don't have it yet, so I can't testify first hand.  But the reviewers have run them for several months and been fairly abusive.  I wouldn't go diving with one, but one reviewer strapped it to his dock rail for a couple of hurricanes and then submerged it in the lake (5-10' depth) until the lake froze over and it was still functioning fine.  There was rust on the windage and elevation turrets.

If we've learned one lesson in life and on this board, you get what you pay for and there is a difference between hobby and duty quality.  At the risk of having my buttons torn off, my saber broken and sat on my horse backwards to ride out of the fort, I'm going to buy one of the Palmetto State pistol kits the next time they are on sale.  The prices say they ought to be junk, but I've been checking around, viewing reviewers I trust, and they keep passing the bar.  Plus, when I get a .300 BO, it will be a hobby gun.  I've got a registered SBR, so I can slap the upper on that if I want, or build up a pistol lower, which I was going to do anyway.  On sale, a 9" .300 BO pistol kit (everything but the lower), are $300-400.  I can spend that, decide if I like it, and if I do, and want something better/different, I can lay down more serious cash.  Or just keep it as a hobby rifle.

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Mark

Swear allegiance to the flag Whatever flag they offer

Never hint at what you really feel

Teach the children quietly For some day sons and daughters

Will rise up and fight while we stood still

 

Joined:  2/24/2003                          Location:  Nevada, USA

For the OP: I did my first .300BLK build at the tail end of the  Bravo Course a couple of years ago. I put a Faxon 10.5” barrel on an Anderson pistol lower with a DSG upper and bolt carrier assembly. It’s pistol length, straight tube. H2 buffer, Geissele, blah blah

It’s had a lot of rounds through it. Supers, subs, from 110gr-220gr. Suppressed and unsuppressed. Frangible, etc. That Faxon barrel holds just a smidge over 1” at 100, to this day. 

My point is that you don’t have to spend a lot if some of your key components are solid, and you don’t really need any specialized or hard-to-find parts to get yourself a build that will get the results you want. 

Oh, and FWIW, my next build used a Faxon .308 Big Gunner barrel and was wringing 3/4 MOA out of 149gr M80 ball all day. 

 

“Is that when you snap a guy’s neck after you been torturin’ him, so he don’t gotta go through the rest of his life with a colostomy bag?”

Mark, 

The 300 I'm building is PSA.

Pistol registered lower - complete 99.00 including the local transfer fee.

9" upper complete with bolt / carrier and mlock rail (no sights though) - 229.00

Magpul mbus front and rear 59.00 AAFES sale. 

S&B brace- 49.00 Midway USA. 

Issues noted- gas block loose, gas key not staked. Resolved in less than 15 mins. 

Buffer tube (full round pistol tube) no locktite. Resolved less than 5 mins.

Other notes- checked headspace with go/nogo and it's good.

1500 rounds (supersonic) no malfunctions - at all.

Ejection is consistent within a loading. I could put a 5gal bucket on the ground and catch 90% of them if I wanted.

Prints best at 100m with S&B 123gr fmj. Off hand iron sights 10 rds less than 1.5"... Good enough for me.

Docs recommended load runs about 1.75"... But that could very well be me...

Overall pleasantly surprised. But still a long way to go



Dave

------------------------------------- "A True Warrior knows neither Left or Right"  Looking for a doc who can fix my allergies.. Stupid People and IED's...

Then I'll be in good company!

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Mark

Swear allegiance to the flag Whatever flag they offer

Never hint at what you really feel

Teach the children quietly For some day sons and daughters

Will rise up and fight while we stood still

 

Joined:  2/24/2003                          Location:  Nevada, USA

Before the sideways looks and comments begin... I want everyone to understand... This build is to let me figure out if I want to pursue the 300 BO further.  I did the same thing with 6.8, but using M&A Parts instead of PSA. This is NOT a work / bet anyone's life on it build. This is a get my feet wet and see if the juice is worth the squeeze build. 

------------------------------------- "A True Warrior knows neither Left or Right"  Looking for a doc who can fix my allergies.. Stupid People and IED's...

That’s why I ordered my upper from PSA, it was cheap and I was Blackout pistol curious.   Plus my earlier 16” build with the Daniel Defense S2W barrel was shooting so well.    The PSA upper has a heavy SS barrel and is overgassed but it will shoot anything you stuff in it.  An H2 buffer finally calmed recoil down a bit.

In my humble opinion, the Blackout is kind of a fun little cartridge.  I wonder how it or something like the .300 Ham’r would have been accepted in the 60’s if it were introduced in the original M16 instead of that .223 varmint round.  I think the gents used to 7.62 rifles might have been a bit more open minded.

I went ahead and got a Holosun HE510.  It powers up and turns itself off. Also has a solar panel on top so in the daylight the sun powers the dot rather than the battery.  Pretty good reviews, and like David Reeves said- this is on an AR pistol, my life ain't gonna depend on it unless a whistle pig charges me at the range.  

My good friend just put together a .300 BO, and has been trying to talk me into one. I stayed with 5.56, as I don't need to stockpile another 50,000 rounds of another caliber.

However.................I am afraid if someone does start a dedicated .300 Blackout build thread, my mind might be changed.  

So LF likes pigtail gas tubes now?

Recently finished (may change when I buy a 30 cal can...) a 300 AAC pistol (aka Schwein Abwer Pistole)

 

PSA Snek lower

LRT MBT trigger

AR-Stoner billet upper and 7" mlok handguard

Ballistic Advantage 8" performance series barrel

VG6 Precision Gamma .30 cal muzzle break

magpul K2 grip

SBA3 brace

aimpoint pro in LRT 129 mount

el-cheepo primary arms long eye relief 3x magnifier in primary arms flip to side mount, depending on how I end up liking this will either get swapped for a poverty acog (primary arms or burris 3x prism sight) or will get a better magnifier, right now I'm leaning towards better magnifier.

 

So when BCM decided to get behind the 300blk, I bout the 9.5" upper.  I planned to spend the winter working up loads for it.  Well, it took two loading sessions  and range days to accomplish. The thing eats everything.  Supers, no problem.  Subs, same.  I can ring the steel at 400 yes with the proper hold over.  It runs just like my EAG tactical carbine, without issue.  

It sits on my sbr lower but I can put it on my pistol lower when I cross state lines, etc.

So my Chymera is in NAF jail until fall-Ish.  Looking forward to running the subs in silenced mode.  The 300 blk is a really neat, accurate and easy to shoot cartridge.  I can't say enough good things about BCM.

jto

Southern Oregon, the redneck part...

Joined 2/28/11

I guess that I come out of the closet with my .300 BO PSA upper, 10.5" barrel, on a PSA pistol lower.   Has run well with any 123 gr. loads, about 300.  At the beginning, subsonic rounds would sometimes short-stroke, but that seems to have gone away.  I use a Primary Arms 50k hour red dots.  So far, so good with everything.

I found a deal on some ADI with 123 gr. SMK bullets and found it quite accurate for practice.  So far, just a range toy.  I plan to sight-in some hunting ammo and reduce the deer population this fall.

To the top with the title change.

-------------------------

IT'S A COLT.  THEY'RE LIKE THE HK OF GUNS.

HRH (Ret.) The Most Reverend Consig

Stupidity is not a skillset.

 

 

 

 

 Joined: 28 Nov 2004: 0037hrs        Location: The worst run state in the U.S

Can you call it a "Schwein Abwer Pistole" if it isn't a re-barreled HK416?   Maybe call it a SAP for short.  

And this isn't a .300 BO HK416, but it is another example of HK quality control...back to the guy who programmed the CNC machine making their handguards.  This photo was taken at SHOT.  25JAN2019 to be exact.

IMG_1546

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Mark

Swear allegiance to the flag Whatever flag they offer

Never hint at what you really feel

Teach the children quietly For some day sons and daughters

Will rise up and fight while we stood still

 

Joined:  2/24/2003                          Location:  Nevada, USA

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Currently: 

DSG complete upper made for them (at a price point) by Seekins. 10.5" barrel by ?, setscrew gas block that we had to fix after about 50 rounds, but seems secure now. Except for the gas block issue, runs 100% so far, several ammo types, with no mods on my lower which runs an H buffer over a (regularly replaced) normal chrome silicon spring for the 5.56, 9mm and .300 without any issues. Pistol length gas system, no adjustments, no pigtails. 

Mepro Tru Dot RDS of course, old school 4x EoTech magnifier but it's heavy so need to replace it sometime. All this works well to stick the clipon in front. Have not fired it like this, need the suppressor to not blow up the front lens on the PVS30:

I hate the rail for several reasons, so will get an Alpha rail like my other carbines sometime here. And, eventually (13 months!) I'll be permitted to get the suppressor, so will get that muzzle device on there and really start using this more. Suppressor may well change how the gun runs of course, so to be seen. 

Also planned to try out is an Arca rail chunk, to tripod it as time permits. I have tried a couple bipods because it was intended to be a short range "precision rifle" but none of them make me happy. 

Used to have a MARS which got me free built in laser, but I have gotten rid of that. So also likely to go with laser but with clipon compatibility that will have to be mounted on the side and... not sure then as it's different. 

Needs forward sling loop. 

Not sure, but likely to also set up with white light to match the other carbines. 5.56 SBR shown here for config comparison:

(Tape is always notes for projects. need to re-zero, part is loose, etc. Sometimes, other plans for changes, upgrades, etc that I will do before using it again.)

 

ETA: When I had the PVS-300 I used it on this for a while. Only photo is when it was still in pistol config with the disappointing bipod but still, it's a photo:

I also know I shot it with the PAS19, did the tedious digital zeroing, but seem to have somehow escaped with no photos of that. HUGE scope for this gun. 

The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life. – Theodore Roosevelt

 

Joined: 19NOV2004   Location: Mission, Kansas

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I didn't build it, but got a factory AAC 9" upper in trade which I believe it has a pistol length gas system.  I haven't fired it suppressed yet (waiting) but it seems to eat all of the supers I've fed it.  Sits on a BCM lower with a standard spring and a H2 buffer.  Before I got it, I was fighting the same gas length/gas port/buffer/WTF-ever battle.  Being a factory upper from AAC, I felt pretty confident it was configured properly and so far, that's been the case.

"These are the rules. Everybody fights, nobody quits. If you don't do your job I'll kill you myself."

 

Joined: 04/01/2004     Location:  Twin Cities, MN

My current set up is a KAK 8.5”  barrel, radical firearms brake and flash can, 10” yhm handguard with a wmlx light at 12 position aero precision upper/lower PSA premium build kit, novske bcg, h2 buffer standard spring. So far it’s been 100% with ~500 130gr steel core pull downs and ~500 125gr Nosler ballistic tips I reload with.  I haven’t done any formal accuracy testing but it’s minute of clay pidgeon at 150 and I can regularly hit a 60% ipsc at 420 with red dot when i do my part. I’ve been happy with the build so far although I’m going to find some better handguards for it. The radical blast can and brake are heavy bastards and i wouldn’t run them on much longer of a barrel but they do balance ok on the shorty. The whole thing was basically built from my spares box to get my feet wet. Running the same 125gr load out of a 16” barrel only gained 100 FPS so I figure the 8.5” is pretty efficient and if I was going to go longer In barrel I would probably just do another 6.8 but that’s another subject.  As for cheap red dots I have been running the vortex sparc 2, it functions but not sure how much I trust it. We killed the first one on a 45-70 guide gun with a quickness, this was the replacement and has lasted so far on the pistol. All in all it makes a nice truck/travel gun for our rural area, I can hide most of it under the arm rest of my truck.  A law folder and new handguard are in the near future then I’ll start saving for a can. 

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Originally Posted by DocGKR:

       
This is why LE in some areas would be better served with belt fed weapons and flame throwers...

       

Joined: 5.23.2009
Location: WA/ Canadian border

I too have been considering a jump into the 300 BLK pool.  I, like others, am considering a hobby grade gun to shoot with both sub and hypersonic ammo.  I have a NFA lower, so I was considering a 10.5” ish upper.  I have seen them advertised with both pistol and carbine length gas systems.  Any advantage of 1 over the other?  I have a Surefire Socom can in NFA hell that I would also like to incorporate.  Thoughts?

"Experience is directly proportional to the amount of equipment broken"

Others with more experience on the platform may know better, I built my own and a buddy built a 16” at the same time after buying a factory 10” build but neither of us run suppressed at this point.  From my reading and experience with his 16”, carbine gas doesn’t play well with subs at least unsuppressed. I would go pistol length with one of the adjustable gas blocks and or play with buffer weight.  Slr has a pretty good reputation, I have the Odin works tuneable block on mine and has worked well so far but it is a set it and forget it type set up rather than a loud vs quiet setting. 

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Originally Posted by DocGKR:

       
This is why LE in some areas would be better served with belt fed weapons and flame throwers...

       

Joined: 5.23.2009
Location: WA/ Canadian border

For those of ya'll that are reloading for .300 Blackout, what powders are you using.  I have a feeling I am going to get roped into reloading for my friends 9" barreled one. (No can.)  He talked about using 125's and 220's.  

Maybe this should have gone into the ammo/ballistics section?

Bill, we have been running ~17gr h110/w296 with the 125s, it changes depending if I’m using converted or factory brass.  Haven’t played with the heavies outside of factory ammo but lil’ gun and AA1680 are popular for them. 

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Originally Posted by DocGKR:

       
This is why LE in some areas would be better served with belt fed weapons and flame throwers...

       

Joined: 5.23.2009
Location: WA/ Canadian border

Consigliere,
I built my 6.8 on a Bison Armory barrel. I have been pleased with it, and would build a .300 on a Bison if I didn't hit the easy button and buy a BCM barrel or complete upper.

For the .300, there is a lot to be said for going short and suppressed, even with full power loads.

My 6.8 is a 16" with my Surefire FA7.62SS attached. Even thought it is a OTB design the whole package feels long after years of SBR and SBR with supressor.

This is the wordy way of suggesting a 9" "pistol" barrel for your .300 BO project.

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