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Posted: 5/30/2021 9:39:29 PM EDT
[#1]
Subs more than likely won't cycle without a can.
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Posted: 5/30/2021 9:42:56 PM EDT
[#2]
Quote HistoryQuoted: Subs more than likely won't cycle without a can. Oh I didn’t know that! Assume they need the added pressure a can gives..? Well shit so much for that. How loud are supers vs 5.56 in 16” and 10.5? |
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Posted: 5/30/2021 9:48:48 PM EDT
[#3]
Quote HistoryQuoted: Subs more than likely won't cycle without a can. |
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Posted: 5/30/2021 9:56:07 PM EDT
[#4]
There is no reason that a properly built AR15 in 300blk cannot cycle with subs and no can.
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Posted: 5/30/2021 9:56:09 PM EDT
[#5]
Quote HistoryQuoted: Certainly not without some tweaking. Quote HistoryQuoted: Quoted: Subs more than likely won't cycle without a can. That’s the equivalent of saying “556 isn’t accurate”. Some will cycle, some won’t. And to your question OP: never use subsonic if you don’t need it to be quiet (unless we are talking rimfire). If you are killing people, you want supersonic velocity and terminal effects |
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Posted: 5/30/2021 9:57:10 PM EDT
[#6]
Depends on the build. Im running a 8.3” BA Hansen and have no issues cycling subs without a can. Can transition to supers no problem with no changes.
Im running a LWRC UCIW buffer tube; I have several different spring/buffer combinations. The UCIW buffer and spring will cycle subs suppressed and supers unsuppressed I have a modified Geissele 42 spring and buffer that hits a sweet spot and will cycle subs unsupressed. |
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Posted: 5/30/2021 9:57:10 PM EDT
[#7]
This is why I built an AR-9 for home defense. A 300 shooting a 200 grain sub offers little if any performance advantage over a 9mm shooting 147's, but you don't need a can to run the 9 and it will cycle anything. They are all loud, but if you light off a 5.56 indoors without ear-pro you will hear that shot for the rest of your life. My ears have been ringing for nearly 40 years now, 24/7
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Posted: 5/30/2021 10:56:08 PM EDT
[#8]
Buy a $50 pair of HL IS muffs and keep them by the rifle.
Pick 300 BLK. Load with 110gr Black Tips. This is the correct solution for your situation. Anything else is sub optimal. I try to avoid sub optimal if I can help it and my life would literally depend on it if it came to a HD situation. |
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Posted: 5/31/2021 12:15:24 AM EDT
[#9]
Quote HistoryQuoted: This is why I built an AR-9 for home defense. A 300 shooting a 200 grain sub offers little if any performance advantage over a 9mm shooting 147's, but you don't need a can to run the 9 and it will cycle anything. They are all loud, but if you light off a 5.56 indoors without ear-pro you will hear that shot for the rest of your life. My ears have been ringing for nearly 40 years now, 24/7 I find this to be false in my experience. I have done shoot houses where I forgot my plethora between iterations and I dealt with breaches, bangers, and a fuck ton of shots in a shoot house. My hearing didn’t have any permanent damage as a result. And anything subsonic or particularly pistol caliber is a serious step down in effectiveness compared to a supersonic rifle round. Don’t handicap yourself |
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Posted: 5/31/2021 1:16:20 AM EDT
[#10]
Spikes Tactical Barking Spider II adds backpressure and directs sound forward. If you find your build will not cycle this may be a solution to run sub sonic ammo. PSA pistol uppers seem to cycle without it but the have pistol length gas systems.
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Posted: 5/31/2021 9:12:10 AM EDT
[#11]
Lehigh/Ventura .300BLK 194gr Maximum Expansion, will cut more tissue than 9mm Federal 147gr HST's. They expand 100%, based on the YouTube Gel and Hog Hunting videos out there. And while not a big deal for HD, the .300BLK Bullet BC's are up there (.560 on S&B 200's) - so any longer range shots, will be easier. Can or not, they should work fine in a properly built gun - gas ports are usually way over-sized to prevent angry letters to Daniel Defense et al, about "my .300BLK won't cycle Subs!"
 The Howard Leights next to the 110gr Tac-TX loaded gun is a good idea too - the on/off wheel on them, is fast AF to use. |
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Posted: 5/31/2021 9:18:15 PM EDT
[#12]
I have two 300blk pistols with Radical Firearms barrels one in 10.5" and one in 8.5" both cycle subs and supers with or without a can without any issues at all. I had a 14.5" 300blk Mas Defense barrel as well at one point that never had any issues with subs or supers. All them had pistol length gas systems.
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Posted: 5/31/2021 9:57:39 PM EDT
[#13]
I have 2 8.5" 300's, one with an adjustable gas block and one without. They both run supers and subs with or without suppressors no problem. For HD one is setup with a can and Hornady 194 subs. For funsies I reload 220's and they run like a top. I will say, when I was testing some of those loads, I was quite surprised how loud they were and what a fireball they produced without a can in an indoor range. I don't think they have the DB's a 16" 5.56 does, but the flash was bigger and it'd still be pretty unpleasant.
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Posted: 5/31/2021 10:17:35 PM EDT
[#14]
Quote HistoryQuoted: Subs more than likely won't cycle without a can. Not true as long as you have pistol length gas. Mine works just fine with 220gr FMJ. |
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Posted: 5/31/2021 10:24:31 PM EDT
[#15]
A bullet that I have had great luck with in my 6.500" .30 HRT is the Hornady 190 gr. SubEX bullet at 1050 fps. It functions perfectly without a can so I cannot imagine it not working with a can should you ever want to do so. I don't see why it would work OK in the .30 HRT and not in the .300 BO unless it has to do with the HRT using slightly more powder to push the same bullet to the same velocity and probably near the same or slightly lower pressures.
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Posted: 6/1/2021 3:34:06 PM EDT
[#16]
Thanks for all the replies guys...
Sounds like you can run subs reliably without a can... sounds like you just need to use pistol length gas tube and an adjustable gas block to help tune it. If I wanted to build one what else should I be considering? Buffer weight I would imagine comes into play, not sure what is recommended? Spring weights can also be changed or a lightweight BCG Is a 300bo pistol with a 8"-ish barrel a good choice for HD? I have read a lot about ballistics and possbile "over penetration" ... but anything else I should consider? In all realitly, an AR style weapon wouldn't be my first choice if something goes bump in the night - a Glock 17 or 12ga would probably be my first firearm I'd grab... but IF i "had" to use an AR style, god forbid, 300bo seems a better option than my 5.56 firearms considering everything would be well within 100yrds, and probably mostly all inside of 50 yrds. I can't see a reason, other than aliens or zombies, an AR in 223/556 would be "needed" and would be shooting at something 300-500 yrds away... EDIT: the more I read, the more this might not be "worth it" since i don't plan on getting a supressor... and people keep saying 300bo subs have the same ballistics as a pistol and the 300bo ammo cost makes it a "waste" 300bo is much larger and expands more, but man this is a pain.... I guess, I either need to get a surpressor to make it worth it, or just build a 9mm PCC and be done with it. |
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Posted: 6/1/2021 4:57:33 PM EDT
[#17]
I would reconsider. A dedicated 300 Blackout shooting subs with no can is really not ideal for anything.
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Posted: 6/1/2021 7:15:09 PM EDT
[#18]
Quote HistoryQuoted: Thanks for all the replies guys... Sounds like you can run subs reliably without a can... sounds like you just need to use pistol length gas tube and an adjustable gas block to help tune it. If I wanted to build one what else should I be considering? Buffer weight I would imagine comes into play, not sure what is recommended? Spring weights can also be changed or a lightweight BCG Is a 300bo pistol with a 8"-ish barrel a good choice for HD? I have read a lot about ballistics and possbile "over penetration" ... but anything else I should consider? In all realitly, an AR style weapon wouldn't be my first choice if something goes bump in the night - a Glock 17 or 12ga would probably be my first firearm I'd grab... but IF i "had" to use an AR style, god forbid, 300bo seems a better option than my 5.56 firearms considering everything would be well within 100yrds, and probably mostly all inside of 50 yrds. I can't see a reason, other than aliens or zombies, an AR in 223/556 would be "needed" and would be shooting at something 300-500 yrds away... EDIT: the more I read, the more this might not be "worth it" since i don't plan on getting a supressor... and people keep saying 300bo subs have the same ballistics as a pistol and the 300bo ammo cost makes it a "waste" 300bo is much larger and expands more, but man this is a pain.... I guess, I either need to get a surpressor to make it worth it, or just build a 9mm PCC and be done with it. There are two different questions here. First, is an 8"'ish .300blk pistol a good HD weapon? Hell yes! But running with just subs and no can is a different question. The best subsonic ammo (Lehigh or Maker) is REALLY expensive. I'm in Illinois, so I can't run a suppressor. I have a lot of .300blk uppers, but I run supers. |
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Posted: 6/1/2021 7:28:39 PM EDT
[#19]
I have an 8” Palmetto upper.
Can or no-can, it cycles absolutely everything subs or supers except Trail Boss. Standard carbine buffer and spring. I’ve shot several powders for handloads. It liked each of them. I’ve settled on H-110 for supers, and CFE/BLK for subs. It was a godawful barky miserable little bitch with supers and no can. Now that it has the can, I doubt I’ll ever shoot it again without the can. No current plans to shoot any more subs either. My shooting opportunities for the gun will allow supers, and no foreseeable scenario that would call for deliberately shooting low-power ammunition. So, supers it is. |
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Posted: 6/1/2021 7:55:07 PM EDT
[#20]
Quote HistoryQuoted: There are two different questions here. First, is an 8"'ish .300blk pistol a good HD weapon? Hell yes! But running with just subs and no can is a different question. The best subsonic ammo (Lehigh or Maker) is REALLY expensive. I'm in Illinois, so I can't run a suppressor. I have a lot of .300blk uppers, but I run supers. Are supers a good HD option? … I ASSUMED subs would just be better with the larger bullet and possibly quieter, but you know what they say about assumptions… I have a complete lower built just need to decide what to do for an upper… thought 300 build would be practical and something different, but I want a build strictly for HD. I think I’ve come to the conclusion that subs without a can isn’t ‘worth it’ … but that doesn’t rule out a 300 build just yet… Still learning and doing research… I do appreciate everyone’s input thus far. |
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Posted: 6/1/2021 8:14:08 PM EDT
[#21]
I guarantee if you put a bullet of any stripe from 300 BLACKOUT inside the 8-ring of a goblin, you will win that hand.
 Attached File |
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Posted: 6/1/2021 8:17:14 PM EDT
[#22]
Seriously, if you’re gonna use a shorty 300BO for home defense, at least put a blast can on it.
 Attached File |
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Posted: 6/1/2021 9:01:34 PM EDT
[#23]
Buy a can.
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Posted: 6/1/2021 9:48:56 PM EDT
[#24]
Quote HistoryQuoted: Are supers a good HD option? … I ASSUMED subs would just be better with the larger bullet and possibly quieter, but you know what they say about assumptions… I have a complete lower built just need to decide what to do for an upper… thought 300 build would be practical and something different, but I want a build strictly for HD. I think I’ve come to the conclusion that subs without a can isn’t ‘worth it’ … but that doesn’t rule out a 300 build just yet… Still learning and doing research… I do appreciate everyone’s input thus far. Supers all the way. Barnes 110gr are kinda the standard by which all others are judged. Where 300BLK shines is the ability to maintain energy out of a really short barrel. This makes them very handy for HD. You don’t get the muzzle blast like you do with a short barreled 5.56. The ability to switch from supers to subs is a nice feature, but there are few subsonic rounds that are suitable for HD. Most will over penetrate walls and ice-pick through soft tissue. Supers are your safe bet if using the round for HD. |
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Posted: 6/1/2021 10:32:15 PM EDT
[#25]
Quote HistoryQuoted: Are supers a good HD option? … I ASSUMED subs would just be better with the larger bullet and possibly quieter, but you know what they say about assumptions… I have a complete lower built just need to decide what to do for an upper… thought 300 build would be practical and something different, but I want a build strictly for HD. I think I’ve come to the conclusion that subs without a can isn’t ‘worth it’ … but that doesn’t rule out a 300 build just yet… Still learning and doing research… I do appreciate everyone’s input thus far. Yes While subs would a bit quieter, it is a pretty big reduction in performance. There are a good half-dozen supersonic rounds that seem to be best performers out of short barrel .300blk. 110gr Barnes Tac-tx (Either Barnes or Wilson Combat loaded) 110gr Hornady Black V-max 110gr Nosler Varmageddon (Underwood loading) 115gr Lehigh Controlled Chaos (Lehigh or Underwood loading) 120gr Sig HT Elite Hunting or SBR 125gr Hornady SST (Fiocchi loading) Lehigh and Maker make excellent expanding subs that would probably work.....but why chance it? |
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Posted: 6/2/2021 7:12:04 AM EDT
[#26]
Quote HistoryQuoted: I’ve shot several powders for handloads. It liked each of them. I’ve settled on H-110 for supers, and CFE/BLK for subs. You'll probably know the answer to this question I had, re: cycling Subs. How much different are the powder charges, between say, a Hornady Super load, and a Hornady Sub load? I was under the impression that the bullet weight was the *general* controlling factor for velocity, and the charge pressure was *generally* close between the two? In which case, there should be no problem "cycling" either, in a properly built/bought gun. Thanks! |
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Posted: 6/2/2021 8:20:59 AM EDT
[#27]
Quote HistoryQuoted: You'll probably know the answer to this question I had, re: cycling Subs. How much different are the powder charges, between say, a Hornady Super load, and a Hornady Sub load? I was under the impression that the bullet weight was the *general* controlling factor for velocity, and the charge pressure was *generally* close between the two? In which case, there should be no problem "cycling" either, in a properly built/bought gun. Thanks! Powder charges are significantly different. I have done EXTENSIVE 300 BLK testing for the past 8 years. I've tested most of the powders that are popular for 300 BLK long before they were mainstream. For apples to apples, I'll use a powder that can be used for both Subs and Supers, like LilGun. Powder charges for supers can be around 21gr (depending on bullet) while subs can be as low as 8gr. Due to the much decreased powder charge, that causes a lot less gas to be generated, which is really the issue on getting subs to cycle properly. That is why in the early days, 1680 was such a popular 300 BLK Sub powder. It generates gobs and gobs of gas, which aid in reliability. The downside is it is loud, and separately, fairly dirty. It's also why LilGun is just about the quietest powder you can get...you can get to 1,050 FPS with very little powder. The 217's I run only require about 7.3gr of Lil'Gun. That's not a lot of gas being generated. It's quiet alright, but it can be finicky to get running. Then of course you have a ton of powders between these two that are all a trade off between reliability, and sound signature. I've found N120 to be the best powder for 300 BLK subs. Now for supers, it's a different story. I'm always looking for the best performance period, with little regard to sound. Supers will always generate enough gas to cycle just fine, so it really comes down to group size (if that's your thing) and terminal performance. I've found H110 to be the best powder for 300 BLK supers. |
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Posted: 6/2/2021 9:39:46 AM EDT
[#28]
Quote HistoryQuoted: Powder charges are significantly different. I have done EXTENSIVE 300 BLK testing for the past 8 years. I've tested most of the powders that are popular for 300 BLK long before they were mainstream. For apples to apples, I'll use a powder that can be used for both Subs and Supers, like LilGun. Powder charges for supers can be around 21gr (depending on bullet) while subs can be as low as 8gr. Due to the much decreased powder charge, that causes a lot less gas to be generated, which is really the issue on getting subs to cycle properly. That is why in the early days, 1680 was such a popular 300 BLK Sub powder. It generates gobs and gobs of gas, which aid in reliability. The downside is it is loud, and separately, fairly dirty. It's also why LilGun is just about the quietest powder you can get...you can get to 1,050 FPS with very little powder. The 217's I run only require about 7.3gr of Lil'Gun. That's not a lot of gas being generated. It's quiet alright, but it can be finicky to get running. Then of course you have a ton of powders between these two that are all a trade off between reliability, and sound signature. I've found N120 to be the best powder for 300 BLK subs. Now for supers, it's a different story. I'm always looking for the best performance period, with little regard to sound. Supers will always generate enough gas to cycle just fine, so it really comes down to group size (if that's your thing) and terminal performance. I've found H110 to be the best powder for 300 BLK supers. Awesome, thanks for the detailed info! I always learn something - the charges/pressures are different. I guess that means OEM Gas Ports must be sized for Subs? |
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Posted: 6/2/2021 10:13:24 AM EDT
[#29]
Quote HistoryQuoted: Awesome, thanks for the detailed info! I always learn something - the charges/pressures are different. I guess that means OEM Gas Ports must be sized for Subs? Depends on the Mfg. Most run a little larger as it's way easier to undergas a 300 BLK than overgas, and you need to be way, way overgassed before you start seeing reliability issues. Reliability issues are readily apparent when you are even slightly undergassed. |
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Posted: 6/2/2021 10:49:11 AM EDT
[#30]
Quote HistoryQuoted:
There is no reason that a properly built AR15 in 300blk cannot cycle with subs and no can. Reloaders pick a projectile, powder, and load that works with their setup. Many did it so long ago that they have forgotten, and think that subs are a universal quantity. |
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Posted: 6/2/2021 11:07:47 AM EDT
[#31]
Quote HistoryQuoted: There is no reason that a properly built AR15 in 300blk cannot cycle with subs and no can. Barrels ported with the intent of having a reasonable rate of fire on auto with suppressed SuperSonics aren’t meant to shoot subsonics unsuppressed. Make of that what you will. |
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Posted: 6/2/2021 11:08:31 AM EDT
[#32]
Quote HistoryQuoted: I find this to be false in my experience. I have done shoot houses where I forgot my plethora between iterations and I dealt with breaches, bangers, and a fuck ton of shots in a shoot house. My hearing didn’t have any permanent damage as a result. And anything subsonic or particularly pistol caliber is a serious step down in effectiveness compared to a supersonic rifle round. Don’t handicap yourself A friend was sitting on an M1A1 when the 120mm was fired. He looks at your lips when you talk to him. YMMV. |
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Posted: 6/3/2021 11:35:25 PM EDT
[#33]
Reliability with Supers and Subs depends on the build.
IMHO the Sig Sauer MCX lineup is pretty much the BEST option for 300 Blackout. It will run Supers or Subsonics with or without a Suppressor. For an AR15, I suggest an adjustable gas system. That should give you enough flexibility to run it any way you want. |
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Posted: 6/4/2021 10:30:47 AM EDT
[#34]
I have done shoot houses where I forgot my plethora between iterations and I dealt with breaches, bangers, and a fuck ton of shots in a shoot house. My hearing didn’t have any permanent damage as a result. 
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Posted: 6/5/2021 8:53:51 AM EDT
[#35]
Quote HistoryQuoted: Powder charges are significantly different. I have done EXTENSIVE 300 BLK testing for the past 8 years. I've tested most of the powders that are popular for 300 BLK long before they were mainstream. For apples to apples, I'll use a powder that can be used for both Subs and Supers, like LilGun. Powder charges for supers can be around 21gr (depending on bullet) while subs can be as low as 8gr. Due to the much decreased powder charge, that causes a lot less gas to be generated, which is really the issue on getting subs to cycle properly. That is why in the early days, 1680 was such a popular 300 BLK Sub powder. It generates gobs and gobs of gas, which aid in reliability. The downside is it is loud, and separately, fairly dirty. It's also why LilGun is just about the quietest powder you can get...you can get to 1,050 FPS with very little powder. The 217's I run only require about 7.3gr of Lil'Gun. That's not a lot of gas being generated. It's quiet alright, but it can be finicky to get running. Then of course you have a ton of powders between these two that are all a trade off between reliability, and sound signature. I've found N120 to be the best powder for 300 BLK subs. Now for supers, it's a different story. I'm always looking for the best performance period, with little regard to sound. Supers will always generate enough gas to cycle just fine, so it really comes down to group size (if that's your thing) and terminal performance. I've found H110 to be the best powder for 300 BLK supers. @-Obsessed- Do you have any threads/write ups on your experiences? I'd be interested in reading them. Up till now I've used 1680 on subs and h110 on supers, but I just lucked into 8 pounds of lil gun and would like to read up to get a jump on load development. |
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Posted: 6/5/2021 9:28:40 AM EDT
[#36]
Quote HistoryQuoted: I would reconsider. A dedicated 300 Blackout shooting subs with no can is really not ideal for anything. Agreed. My first question was why the aversion to a can? 300 subs, and specially expanding 300 subs are NOT cheap. I think you would best be served by a 9mm PCC as well due to ammo cost, availability of high performing hollow points, etc etc. There are tons of 9mm PCC options. As a 300blk fan, I see zero point in using subs without a can. Everything will be loud without a can. |
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Posted: 6/5/2021 10:29:30 AM EDT
[#37]
Quote HistoryQuoted: @-Obsessed- Do you have any threads/write ups on your experiences? I'd be interested in reading them. Up till now I've used 1680 on subs and h110 on supers, but I just lucked into 8 pounds of lil gun and would like to read up to get a jump on load development. @MallNinja531 I've never put it all into a single post before, but have always provided input to relevant threads as appropriate...the reloading forum is my favorite forum to frequent. I was an earlyish adopter of the round, early enough that dies were special order. It was actually my first AR, and the first rifle round I reloaded for. Initially I chased quiet above all else. Then I started chasing accuracy (to a point, I'm not a Precision shooter by any stretch), then reliability and cleanliness. These days I like a nice all around load that does each fairly well, which is why I've settled on N120. I've reloaded and fired about 18k rounds of 300BLK now, and most of those were experimental in one way or another. 95% of them have been subs. I have only tried a few powders for Supers and very quickly settled on H110. There is a lot to like about that powder. If you have any specific questions shoot me an IM. I'm not the only one who has done extensive testing but happy to share my experiences, however writing 9 years and 18k rounds of history succinctly wouldn't be easy. I'll shoot you an IM with my LilGun experiences. I've burned though 11 lbs of it in 300 BLK and is one of the ones I have done the most experimenting with. I was an early proponent of this powder but has fallen out of favor in my eyes...check your inbox as I don't want to hijack this thread. 
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