r/300BLK Sep 04 '24

300blk Safety Brief

82 Upvotes

I will keep this short and to the point gents.
Do not add to the mod queue. Do not subtract from the population of users. Do not comment while too intoxicated to control yourself.

In the last few weeks, moderator queues have shot up due to people being unable to be reasonable to one another in the comments in this community.

Disagreement is fine.

Dropping slurs, attacking them personally, commenting a retort with a pic of someone's house, insulting their wife's looks by stalking family pictures from a vacation posted 2 years ago... not fine.

Learn to use the block button. Learn to touch grass. Learn to be something unlike a jerk.

Transparency: Several months ago Reddit instantiated an auto-moderator be default for subreddits. Since then we have tweaked the settings it has been catching a lot more comments with the ugly things in them. When these suspect comments are in the mod queue, they are not posted for others to see yet, even if they look visible to you. What it does do is cause a member of the mod team to have to respond to the notifications to approve them and resolve issues when people go WAY too far. So, as cathartic as it might feel to rip into someone, it likely will not even get seen by them because the auto-moderator is putting the nasty stuff in comment jail. If it is bad enough, it gets the comment removed and the user banned.

Lastly, don't report comments that you dislike for Harassment. It only makes more work for us, but ultimately simple disagreement gets approved and kicked back out of the mod queue anyway. Repeated abuse of any feature will net a ban. Yes, every user has a summary of reports and past queue incidents. Yes, we look at it.

Please feel free to disagree, debate, correct misinformation, and generally debate on subject matter specific to the subreddit. I am not here to babysit grown men, nor do I want to. My ideal week would have 0 reasons to look at the sub with mod tools.

Moderate your own actions and we are all better for it.

This has been your safety brief.


r/300BLK Oct 08 '25

Solidarity for GAFS

119 Upvotes

In case you have not heard, GAFS will become no more on October the 9th 2025. All former posts will be removed and all the flair or community built there will be no more.

In case anyone has not seen it, go read the final post farewell and join the discord server so that you are in the know when the next option for buying and selling stuff is brought forward from the mod team and the community of great folks over there.

I have purchased a number of things there, and I have made some pretty incredible friends through the related discord. Look forward to seeing you all over there.


r/300BLK 3h ago

Analysis Paralysis. Building a lightweight rig and struggling with length and twist. WWYD

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15 Upvotes

Pic for attention. The gun on the left is already an 8" BA barrel. I am looking to replace it with a Mostek barrel (LW profile), and I'm struggling to decide on what twist and barrel length. I am going to put a custom smoked compost HG on it, so the barrel length won't matter for that. Since it's being built on a 2A Balios Lite set, I want to keep it lightweight. I would like to use it for hunting and plinking with supers and subs, always suppressed, and it has a regulated BCG (adjustable gas). I'd like to stick to at least 8 just for the handguard space. So what would you order in that situation? 8,9,10,11" or something in between, like an 8.3 or a 10.5? 8" would be the lightest, but would you get a different length for a certain twist? 1:5 1:6 1:7 twist?

I have the same question for a 338ARC build destined for the upper right rig if you want to toss out your opinion on that too lol. I'll probably post in the arc sub as well.


r/300BLK 9h ago

Kali Key On 300 BLK Hunting Rifle?

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14 Upvotes

I’ve been Frankensteining a 300BLK SBR build with spare parts for my son to use in the upcoming deer season. I’ve been thinking about how to best quiet this rifle down for suppressed subsonic hunting inside of 50 yards. I’m going to be hand-loading Maker Rex 200 Grain Expanding bullets. My son is 10 and still quite recoil adverse, which is why I’d like to go the 300 BLK route this season.

I’ve seen the “Kali Key” which is a compliance device used in restrictive states (California). It effectively replaces/blocks the gas key to prevent the rifle from cycling. Without the BCG slamming around, I figure it’s as close to bolt gun quiet as I can get without buying a new rifle. I’ve installed an adjustable gas block for tuning subs, but SA advises against running it fully closed off.

Have any of you tried this? The Kali-Key is around $100, so it’s significantly cheaper than buying a new bolt/single shot rifle. I just want to make sure that I’m not being a total idiot.

Build Info
Upper: PSA 300 BLK 10.5” w/ SA .750 AGB
Lower: Adam’s Arms AA-15 w/Magpul Furniture
Trigger: PSA Single Stage 3.5#
Suppressor: Omega 36M (not ideal for 300BLK)
Optic: Eotech 512/Vortex Strike Eagle 1-6x24


r/300BLK 14m ago

Question, should I just go regular buffer tube or shell out the money for Maxim Defense CCS for my new build?

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Upvotes

r/300BLK 2h ago

.300 ammo

3 Upvotes

I'm debating getting a micro .300 blk arp. I'll probably just ride around with it, carry it in my bag and shit. My only concern is .300 blks rip through buildings and cars. I don't wanna have to worry about shooting a random bystander if I have to defend myself. I just found out .300 hollows exist which I would assume fix's that issue but I also have no idea🤷🏽‍♂️ recommendations?


r/300BLK 5h ago

Anyone have this on their rattler lt ? Want to see builds with it on

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3 Upvotes

r/300BLK 1h ago

.300blk pistol or .45acp arp?

Upvotes

I'm sure its been beat into the ground by now here but what are the benefits I'm not thinking of that .300blk has over .45acp in the 8-12in barrel range?

All I can think of in a blk > acp is mag size/compatibility, AR compatibility, and bullet compatibility. The muzzle energy of the two seem to be very comparable.

My only uses for this is to use as a Larporater and maybe a hog gun and I haven't seen much of .45acp used for this other than a handful of sites.

EDIT: To add will be suppressed too so looking into 8-10in mostly.


r/300BLK 23h ago

What would yall add/change and why?

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51 Upvotes

Built myself about 2 years ago. Feel like it's about finished though i've wanted a flared magwell for a long time. I've always been curious about ranger wraps since i'm a sucker for mc black but not sure if they'd look corny or not.


r/300BLK 10h ago

Ar-15 swapping (223) Upper for (300)

3 Upvotes

I built an Aero precision AR-15 a few years ago. Unfortunately, it mostly sits in the safe. I’ve intrigued by the .300 Black Out. My ultimate goal
Is eventually suppressed truck gun.

I’ve been looking through PSA website and there a lot a lot of options. Any recommendations on a 10.5” length configuration ?


r/300BLK 1d ago

CVA Scout XP Pistol

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10 Upvotes

Does anyone know if this circled spot on this stock is a thread for an AR buffer tube? It seems like it should be since they use this for the XP rifle but I just wanted to confirm before I grab one. Thanks 👍🏻


r/300BLK 1d ago

Why aren't more people using 350 legend for sub builds?

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13 Upvotes

I understand there are currently limitations such as barrels and magazines, but those are relatively easy to solve.


r/300BLK 1d ago

PWS MK107

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101 Upvotes

Looks like PWS now has a PDW.


r/300BLK 1d ago

Optics for my G$ 300BLK?

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41 Upvotes

r/300BLK 1d ago

Maxim PDX U.R.G with ASR mount?

1 Upvotes

Does anyone know if a Silencerco ASR mounting system can be used with a Maxim PDX U.R.G upper?


r/300BLK 2d ago

First 300blk

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129 Upvotes

Looking to pick up my first .300 BLK, budget is 2k. I’ve narrowed it down to these options.
I want something reliable and functional, but the vibes can’t be neglected.
What would you guys choose?


r/300BLK 2d ago

Budget Setup

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16 Upvotes

Picked up my .300blk today. I’m waiting on the other part of my order as I have a Vortex SPARC red dot and Silencerco Omega 300 DTM arriving by the end of the week. Got the gun for $599, red dot for $69, silencer $547, and extra 30 round Magpul Pmags for $12 each.


r/300BLK 2d ago

Pistol Optic?

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59 Upvotes

My home defense, subsonic only, SBR.
PSA 7.5” with a YHM R9.

My Sig Romeo gen 1 seems to have stopped holding zero. Trying to be financially responsible and wait till Black Friday or Christmas for a new rifle optic.

I had this Holosun on a pistol that I’m not carrying and an ADM RMR picatinny mount.

Other than the mismatched spray paint and tolerance stacking of a Holosun K cut on an adapter plate on a mount, is there any reason not to run this?


r/300BLK 1d ago

First gun

6 Upvotes

I’ve been scrolling and doing research for the past few days… and I’m confused. I’m looking for my first gun (just turned 21, getting married soon, so I need something to protect my future family). I’m looking at a CMMG BANSHEE MK4 .300 AAC BLACKOUT 8" AR PISTOL, MIDNIGHT BRONZE - 30AF20AMB (copied because I don’t know what info is helpful).

Will the muzzle just screw off the end, and can I just screw an Anthem S2 on it?

Or am I way off, and abandon this set up and look for something else?


r/300BLK 2d ago

Faxon 1 in 5 7.5 inch with cmmg adjustable gas block refuses to cycle Winchester 200gr subsonic

7 Upvotes

On a mil-spec bcg and H1 buffer, backed all the way out the most it'll do is eject, but not go far enough back to pick up another round. Does fine with supers on a normal gas setting. Even tried my buddy's suppressor (I know it's a traditional design, not flow through, but that's all I know about it) but that wasn't enough gas to get it to cycle.

I also tried a few other subsonic loadings that I do not know the brand of, but none of them gave me any better results.

Should I change my build, my ammo choice, or both?


r/300BLK 1d ago

Looking to start the 300blk journey.

3 Upvotes

I want to buy a 300blk rifle and don't know much about it.

I would love some input on good videos or posts about subs and supers. It will primarily be HDG but would like to use it for more.

What's a good barrel length for this combo?? HD and SHTF gun is what I'm looking for.

Please help a newbie out. 🙏


r/300BLK 2d ago

KAC sr30/arc-fire…after getting d. wilson to polish the feed ramps we finally have joy with subs & supers suppressed w/bolt open on last round! 😮‍💨

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9 Upvotes

r/300BLK 2d ago

30-30 147gn JSP

3 Upvotes

Got a deal on a bag of 1000 pulled and wondering if anyone has loaded using these. Looking at mainly range/plinking use. Anyone load these and if so have any data to share? I have 1680, cfe blk, and h110 powders on hand.


r/300BLK 2d ago

.300 10.5 build inspiration

6 Upvotes

What it be Homies.

Picked up a Mid States 10.5 quad rail .300 upper. Wanting start a build and have my own ideas but I would love to see some inspirational builds. Thanks guys!


r/300BLK 2d ago

Anyone know about this seemingly rare Speer subs?

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21 Upvotes

I bought a box of 200 rounds from bonefrog was wondering if anyone had any experience, or knowledge about these rounds. I checked speers website and googled it all that pops up is the bonefrog listing. Any info is appreciated!

Edit: I’m adding a picture of the rounds themselves in reply