testtest

Let's talk 300 BLK twist rates

I'm building a 300 BLK pistol and didn't even consider twist rate. I purchased a 10.5 1:8 twist (https://www.sportsmansguide.com/pro...-bcg-and-charging-handle-105-barrel?a=1879513) upper and then also purchased heavier subsonic rounds.

As I stated before in a different post, this rifle (pistol legally speaking) is a PDW. I can't imagine twist rate in close quarters home defense scenarios is something to consider.
Am I wrong? Would subs in a 1:8 twist perform poorly at such close distances?
 
I'm building a 300 BLK pistol and didn't even consider twist rate. I purchased a 10.5 1:8 twist (https://www.sportsmansguide.com/pro...-bcg-and-charging-handle-105-barrel?a=1879513) upper and then also purchased heavier subsonic rounds.

As I stated before in a different post, this rifle (pistol legally speaking) is a PDW. I can't imagine twist rate in close quarters home defense scenarios is something to consider.
Am I wrong? Would subs in a 1:8 twist perform poorly at such close distances?
Hans and others will have an answer with a higher level expertise; my guess is that the twist is negligible; I'd be more concerned with the performance/feeding of the ammo. In any case, incapacitation odds would seem adequate.
 
1:8 or 1:7. Supersonic loads ( Lighter ) go 1:7. Subsonic loads ( heavier) 1:8.
Twist rate isn't going to have much to do with how it chambers or feeds. It is about stabilizing different weight projectiles. And I would argue for practical purposes the difference between 1:7 and 1:8 is negligible. A subsonic load in 300 BLK might be 225 gr. or more. My .223 Wylde is 1:8 and it handles 55-62 gr. 5.56 admirably. Unless you are competition/bullseye shooting, in my opinion, it's largely irrelevant minutae inherent to just about every hobby a man decides to " Get into". Kinda like my Snap On 1/2" drive ratchet doesn't actually work any better than the Old Craftsman I inherited from my pops. And the Orange Drop cap in my Les Paul really doesn't change anything relevant over a Sprague cap.

I'm not saying there isn't a difference between 1:7 and 1:8, I'm saying it's marginal at best.
 
Last edited:
I imagine it'd chamber and feed like any other providing everything works on like it's supposed to
Twist rate has nothing to do with how you're firearm will feed and it typically only effects the accuracy of the projectile based on weight of the projectile. 9in being the optimal length for full powder burn in .300AAC

If your mostly using it for heavier bullets in the 200gr or above range I'd suggest using the slower twist rate of 1:7 over the 1:8 as the 1:7 will more effectively stabilize the heavier subsonic bullet though either twist can be used in the end as I shoot both twist rates in different barrel lengths with no negative effects.

I have a few .300AAC firearms myself and I personally really like the round for it's versatility especially when shooting suppressed.

.300AAC subsonic ammo is pretty hard to find currently and if you can find some it typically demands a premium. Midway USA sells Berry's 220gr bullets on sale frequently and if you reload you can make you own rounds for roughly 40-50 cents a piece with recycled brass and using the right powder such as LilGun or AA1680.
 
As far as 100% burn you will never get it even in a 16" barrel. You would need a faster burn rate than #9, 296, lil gun, h110 or even 1680. I say this according too quick load. A lighter charge might get you closer to 100%? I don't shoot anything over 185gr so far (still testing) from an 8.5" 1/8 barrel and test against a 16" for good measure. IF you are using subs/190gr or heavier get a dedicated 300bo/300whisper mag. I've heard (from @HansGruber also) it can be a problematic feeding issue using 556/223 mags? A 1/7 would be better for subs given a short barrel.
 
As far as 100% burn you will never get it even in a 16" barrel. You would need a faster burn rate than #9, 296, lil gun, h110 or even 1680. I say this according too quick load. A lighter charge might get you closer to 100%? I don't shoot anything over 185gr so far (still testing) from an 8.5" 1/8 barrel and test against a 16" for good measure. IF you are using subs/190gr or heavier get a dedicated 300bo/300whisper mag. I've heard (from @HansGruber also) it can be a problematic feeding issue using 556/223 mags? A 1/7 would be better for subs given a short barrel.
Magpul makes .300 specific magazines to accommodate longer bullets, as I understand.
 
1:8 or 1:7. Supersonic loads ( Lighter ) go 1:7. Subsonic loads ( heavier) 1:8.
Twist rate isn't going to have much to do with how it chambers or feeds. It is about stabilizing different weight projectiles. And I would argue for practical purposes the difference between 1:7 and 1:8 is negligible. A subsonic load in 300 BLK might be 225 gr. or more. My .223 Wylde is 1:8 and it handles 55-62 gr. 5.56 admirably. Unless you are competition/bullseye shooting, in my opinion, it's largely irrelevant minutae inherent to just about every hobby a man decides to " Get into". Kinda like my Snap On 1/2" drive ratchet doesn't actually work any better than the Old Craftsman I inherited from my pops. And the Orange Drop cap in my Les Paul really doesn't change anything relevant over a Sprague cap.

I'm not saying there isn't a difference between 1:7 and 1:8, I'm saying it's marginal at best.
I think maybe you're mistaken. You said subsonic go 1:8 which is a looser twist than 1:7. Did you mean the reverse?
 
You are correct Magpul does make dedicated .300BLK mags.

I shoot 220 & 240 grains rounds through standard 5.56 gen 2 pmags without issue.
Anything is possible! I might make some 210 and 240 smk for the 300bo, but too expensive! Saving them for the 300wm 30". Maybe several other people got together and came up with a possible issue? I want between 950 and 1,050me for all weight bullets (110-170gr). Range up to 300yards. Just for my wants/needs.
 
I think maybe you're mistaken. You said subsonic go 1:8 which is a looser twist than 1:7. Did you mean the reverse?
Yah. Supersonic and subsonic confusion. :ROFLMAO::ROFLMAO:

You should also remember that my response wasn't based on any actual experience I have, as I have none with 300 BLK. Nor am I particularly knowledgeable about ARs in comparison to 10mm, Hans, KF and others here. Rather I was simply regurgitating shite I have read. :)
 
Yah. Supersonic and subsonic confusion. :ROFLMAO::ROFLMAO:

You should also remember that my response wasn't based on any actual experience I have, as I have none with 300 BLK. Nor am I particularly knowledgeable about ARs in comparison to 10mm, Hans, KF and others here. Rather I was simply regurgitating shite I have read. :)
I'm with you on this as I would not consider myself an expert either but I do have a decent amount of experience with .300blk and I've done a lot of reading on the subject when it comes to that round. All of us are constantly learning about our hobbies and some of us have more time invested in certain calibers or platforms.

To me any input is always welcome and if that input is something I haven't heard before I dig deeper into it furthering my knowledge on the subject.
 
It’s an individual rifle kind of thing, as I understand; some rifles have issues with the heavy bullets and regular 5.56 mags.
I've heard that also and I've also read that certain brands of .300 ammo can be finicky in 5.56 mags when it comes to loading reliably. .300blk mags typically have a slightly different follower so the less tapered subsonic round doesn't get hung up in the mag.

Side note:

It's good practice to have a different ID tag on mags loaded with .300blk so they don't accidentally get loaded and chambered into a 5.56 firearm. Some people use nail polish, paint, Magpul elastic bands or different color mag floor plates to distinguish the two easier.
 
I've heard that also and I've also read that certain brands of .300 ammo can be finicky in 5.56 mags when it comes to loading reliably.

Side note:

It's good practice to have a different ID tag on .300blk mags so they don't accidentally get loaded and chambered into a 5.56 firearm. Some people use nail polish, paint, Magpul elastic bands or different color mag floor plates to distinguish the two easier.
Just my opinion, but if/when I obtain a 300BLK upper I would/will buy 300 BLK PMags and will either get them in FDE or some other color than the black PMags or will somehow label them very visibly to avoid confusing the two.
 
Just my opinion, but if/when I obtain a 300BLK upper I would/will buy 300 BLK PMags and will either get them in FDE or some other color than the black PMags or will somehow label them very visibly to avoid confusing the two.
I may buy some .300blk mags myself soon just to try them out. I already have tons of Gen 2 pmags & Surefeed E2 mags in standard 5.56 that use. I have seen .300blk followers on sale to convert pmags to .300blk for around $3.00 each but these are from companies I'm not familiar with so I'm not sure of the reliability.

.300blk is a great round as it has a lot of versatility as a medium game hunting, plinking or use for HD loadings and it uses a pistol length gas system allowing a much shorter barrel without sacrificing power burn or ballistics.

I'm a huge fan!
 
I may buy some .300blk mags myself soon just to try them out. I already have tons of Gen 2 pmags & Surefeed E2 mags in standard 5.56 that use. I have seen .300blk followers on sale to convert pmags to .300blk for around $3.00 each but these are from companies I'm not familiar with so I'm not sure of the reliability.
My SIL has a 7.5" suppressed 300 BLK and he uses the regular Gen 2 P Mags with no issues. I personally wouldn't. I'm funny like that though. I also won't shoot steel or aluminum cased ammo in anything, won't shoot reloads in semi auto firearms, won't shoot 115 gr. in my German 9MMs, Won't own or play through any amp that doesn't have tubes, etc.. In general I like to use the real stuff, no shortcuts. :cool:
 
I've heard that also and I've also read that certain brands of .300 ammo can be finicky in 5.56 mags when it comes to loading reliably. .300blk mags typically have a slightly different follower so the less tapered subsonic round doesn't get hung up in the mag.

Side note:

It's good practice to have a different ID tag on mags loaded with .300blk so they don't accidentally get loaded and chambered into a 5.56 firearm. Some people use nail polish, paint, Magpul elastic bands or different color mag floor plates to distinguish the two easier.

Can’t see how a .300 would chamber in a 5.56…it’d stop as soon as the bullet the shoulder in the chamber. Bullet would set back, sure, but powder shouldn’t compress enough to allow the bolt to close.

I could see the opposite being more likely—a 5.56 in a .300–but that’s just going to blow the brass out, and maybe cause a baffle strike if using a suppressor…
 
Can’t see how a .300 would chamber in a 5.56…it’d stop as soon as the bullet the shoulder in the chamber. Bullet would set back, sure, but powder shouldn’t compress enough to allow the bolt to close.

I could see the opposite being more likely—a 5.56 in a .300–but that’s just going to blow the brass out, and maybe cause a baffle strike if using a suppressor…
Here's a link from a very reputable firearms maker discussing the potential issue.

You can also find a ton of information online of people accidentally chambering .300blk in 5.56 firearms with catastrophic results.



Here's another good link on the subject.


 
I may buy some .300blk mags myself soon just to try them out. I already have tons of Gen 2 pmags & Surefeed E2 mags in standard 5.56 that use. I have seen .300blk followers on sale to convert pmags to .300blk for around $3.00 each but these are from companies I'm not familiar with so I'm not sure of the reliability.

.300blk is a great round as it has a lot of versatility as a medium game hunting, plinking or use for HD loadings and it uses a pistol length gas system allowing a much shorter barrel without sacrificing power burn or ballistics.

I'm a huge fan!
Its a great hog round. Recoil isnt bad at all. Smidge more than a 5.56 in my opinion. Brings down hogs effectively except for the larger ones where it takes lots of rounds. We have had prob a dozen large hogs take 4+ rounds of .300 BO and keep running.

Edit: the beast the other night took 6 rounds of .300 BO before he dropped.
 
Back
Top