SIGforum.com Main Page Mason's Rifle Room Instruct me on building a .300 Blackout...BARREL ARRIVED :-) EDIT...FINISHED IT UP...
Main Page Mason's Rifle Room Instruct me on building a .300 Blackout...BARREL ARRIVED :-) EDIT...FINISHED IT UP...Page 1 2
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Plowing straight ahead come what may |
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  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 | ||
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My hypocrisy goes only so far |
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 "  | |||
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For real? |
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! | |||
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Member |
For buffer weight I am using Spikes Tactical T3, it help reduce perceived recoil and assisted with ejection patterns. | |||
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Prince of Cats |
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.  | |||
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| Plowing straight ahead come what may |
Well...I came home today and found that my barrel and .308 birdcage were on my front porch  ...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 | |||
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| You're going to feel a little pressure... |
Try these guys for ammo https://octanemunitions.com/pr...kout-220gr-subsonic/ I have a bunch and it's been good to go. Bruce "The designer of the gun had clearly not been instructed to beat about the bush. 'Make it evil,' he'd been told. 'Make it totally clear that this gun has a right end and a wrong end. Make it totally clear to anyone standing at the wrong end that things are going badly for them. If that means sticking all sort of spikes and prongs and blackened bits all over it then so be it. This is not a gun for hanging over the fireplace or sticking in the umbrella stand, it is a gun for going out and making people miserable with." -Douglas Adams “It is just as difficult and dangerous to try to free a people that wants to remain servile as it is to try to enslave a people that wants to remain free." -Niccolo Machiavelli The trouble with fighting for human freedom is that one spends most of one's time defending scoundrels. For it is against scoundrels that oppressive laws are first aimed, and oppression must be stopped at the beginning if it is to be stopped at all. -Mencken | |||
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| You're going to feel a little pressure... |
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 "The designer of the gun had clearly not been instructed to beat about the bush. 'Make it evil,' he'd been told. 'Make it totally clear that this gun has a right end and a wrong end. Make it totally clear to anyone standing at the wrong end that things are going badly for them. If that means sticking all sort of spikes and prongs and blackened bits all over it then so be it. This is not a gun for hanging over the fireplace or sticking in the umbrella stand, it is a gun for going out and making people miserable with." -Douglas Adams “It is just as difficult and dangerous to try to free a people that wants to remain servile as it is to try to enslave a people that wants to remain free." -Niccolo Machiavelli The trouble with fighting for human freedom is that one spends most of one's time defending scoundrels. For it is against scoundrels that oppressive laws are first aimed, and oppression must be stopped at the beginning if it is to be stopped at all. -Mencken | |||
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| ...and now here's Al with the Weather.  |
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. | |||
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| You're going to feel a little pressure... |
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 "The designer of the gun had clearly not been instructed to beat about the bush. 'Make it evil,' he'd been told. 'Make it totally clear that this gun has a right end and a wrong end. Make it totally clear to anyone standing at the wrong end that things are going badly for them. If that means sticking all sort of spikes and prongs and blackened bits all over it then so be it. This is not a gun for hanging over the fireplace or sticking in the umbrella stand, it is a gun for going out and making people miserable with." -Douglas Adams “It is just as difficult and dangerous to try to free a people that wants to remain servile as it is to try to enslave a people that wants to remain free." -Niccolo Machiavelli The trouble with fighting for human freedom is that one spends most of one's time defending scoundrels. For it is against scoundrels that oppressive laws are first aimed, and oppression must be stopped at the beginning if it is to be stopped at all. -Mencken | |||
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Prepared for the Worst, Providing the Best |
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? | |||
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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. | |||
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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. | |||
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| Prepared for the Worst, Providing the Best |
Thanks for the input. May be a better idea to SBR the 9mm, then. | |||
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| Go ahead punk, make my day |
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. | |||
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| Prince of Cats |
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 | |||
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| Plowing straight ahead come what may |
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  . 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 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 | |||
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Member |
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  ________________________ Sic transit gloria mundi Canadian Coast Guard - Retired | |||
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SIGforum.com Main Page Mason's Rifle Room Instruct me on building a .300 Blackout...BARREL ARRIVED :-) EDIT...FINISHED IT UP...
Main Page Mason's Rifle Room Instruct me on building a .300 Blackout...BARREL ARRIVED :-) EDIT...FINISHED IT UP...© SIGforum 2024