AR15.Com Archives
 300 Blackout?
Tommy_G  [Member]
11/28/2012 1:58:17 PM
I'm thinking of building one, any thoughts
Sheddy  [Team Member]
11/28/2012 2:04:49 PM
Sbr with a can shooting subsonic boolits, why not?
JC10311  [Team Member]
11/28/2012 2:19:46 PM
JUST SAY NO!!!!

There are way too many people building 300 BLK guns now and I CAN'T GET BARRELS!

Seriously, I have one in 16" and one in the works with a 10.5". I used the 16" to take a nice button buck this year at 165 yards with 155 gr Poly-point. I frequently shoot steel with it at 300 yards and it's plenty accurate with anything I run through it.
ws-6  [Team Member]
11/28/2012 2:21:29 PM
just have a good plan to keep your .223/5.56 and 300 seperate. both use the same mags, lowers, bolt, etc. you can chamber a .223/5.56 into a 300 barrel. if you did and fired it who knows what would happen as it bounces off the sides of the barrel. also if you are shooting suppressed it might be a good way to damage the suppressor also. there have been some pics of people loading 300 into a .223/5.56 gun with bad consequences also.
EaZeNuTZ33  [Team Member]
11/28/2012 2:24:10 PM
Do it!!!!


If you wanna shoot my 8" 300BLK SBR with silencer, just let me know. Its like a little sample of crack!
ABN-RGR  [Team Member]
11/28/2012 3:04:46 PM
is there a downside to a 20" barrel?
EaZeNuTZ33  [Team Member]
11/28/2012 3:09:01 PM
Originally Posted By ABN-RGR:
is there a downside to a 20" barrel?


ITS LONG AND HEAVY!



My wife has told me for some time....if I cant get the job done with the 8" I have......
JC10311  [Team Member]
11/28/2012 3:10:17 PM
Extra weight for almost no velocity gain. The 300 BLK uses pistol powders that are completely burned before the bullet gets past 16". I believe that the difference between muzzle velocities for 16" to 20" is less than 50 fps. Someone will have the actual stats.
ABN-RGR  [Team Member]
11/28/2012 3:50:08 PM
Thats what I was wondering. Im going to use it for a woods deer gun, so maybe Ill have it cut down.
RJTCCW  [Team Member]
11/28/2012 3:53:53 PM
Originally Posted By ws-6:
just have a good plan to keep your .223/5.56 and 300 seperate. both use the same mags, lowers, bolt, etc. you can chamber a .223/5.56 into a 300 barrel. if you did and fired it who knows what would happen as it bounces off the sides of the barrel. also if you are shooting suppressed it might be a good way to damage the suppressor also. there have been some pics of people loading 300 into a .223/5.56 gun with bad consequences also.


Is the case that much shorter that it would fit into a .223 chamber? Otherwise I cannot imagine a .300 bullet fitting into the front of a .223 chamber.
EaZeNuTZ33  [Team Member]
11/28/2012 4:00:13 PM
Originally Posted By RJTCCW:
Originally Posted By ws-6:
just have a good plan to keep your .223/5.56 and 300 seperate. both use the same mags, lowers, bolt, etc. you can chamber a .223/5.56 into a 300 barrel. if you did and fired it who knows what would happen as it bounces off the sides of the barrel. also if you are shooting suppressed it might be a good way to damage the suppressor also. there have been some pics of people loading 300 into a .223/5.56 gun with bad consequences also.


Is the case that much shorter that it would fit into a .223 chamber? Otherwise I cannot imagine a .300 bullet fitting into the front of a .223 chamber.


I think he means shooting 300BLK in a 5.56 suppressor......there's a pic of an M4-2000 that had a couple 300BLK rounds that tried to squeeze through......looked like an expensive "oopsie"
JC10311  [Team Member]
11/28/2012 4:12:22 PM
Originally Posted By EaZeNuTZ33:
Originally Posted By RJTCCW:
Originally Posted By ws-6:
just have a good plan to keep your .223/5.56 and 300 seperate. both use the same mags, lowers, bolt, etc. you can chamber a .223/5.56 into a 300 barrel. if you did and fired it who knows what would happen as it bounces off the sides of the barrel. also if you are shooting suppressed it might be a good way to damage the suppressor also. there have been some pics of people loading 300 into a .223/5.56 gun with bad consequences also.


Is the case that much shorter that it would fit into a .223 chamber? Otherwise I cannot imagine a .300 bullet fitting into the front of a .223 chamber.


I think he means shooting 300BLK in a 5.56 suppressor......there's a pic of an M4-2000 that had a couple 300BLK rounds that tried to squeeze through......looked like an expensive "oopsie"


There have been a couple of long threads about the possibility of shooting one round through the other gun. It has been demonstrated (painfully) that you can chamber and fire a 300 BLK round in a 5.56 gun. It's only possible with significant bullet setback on chambering, but it can happen. It has also been demonstrated that you CANNOT chamber and fire a .223 round in a 300 BLK gun. The bolt will not close fully so it can't go into battery and therefore the firing pin cannot strike the primer. I was VERY happy with this since my dad tried it for real (accidentally) and the gun would not fire even though the hammer did fall.
RJTCCW  [Team Member]
11/28/2012 4:12:28 PM
Originally Posted By EaZeNuTZ33:
Originally Posted By RJTCCW:
Originally Posted By ws-6:
just have a good plan to keep your .223/5.56 and 300 seperate. both use the same mags, lowers, bolt, etc. you can chamber a .223/5.56 into a 300 barrel. if you did and fired it who knows what would happen as it bounces off the sides of the barrel. also if you are shooting suppressed it might be a good way to damage the suppressor also. there have been some pics of people loading 300 into a .223/5.56 gun with bad consequences also.


Is the case that much shorter that it would fit into a .223 chamber? Otherwise I cannot imagine a .300 bullet fitting into the front of a .223 chamber.


I think he means shooting 300BLK in a 5.56 suppressor......there's a pic of an M4-2000 that had a couple 300BLK rounds that tried to squeeze through......looked like an expensive "oopsie"


Gotcha and thank you sir.
RJTCCW  [Team Member]
11/28/2012 4:14:35 PM
Originally Posted By JC10311:
Originally Posted By EaZeNuTZ33:
Originally Posted By RJTCCW:
Originally Posted By ws-6:
just have a good plan to keep your .223/5.56 and 300 seperate. both use the same mags, lowers, bolt, etc. you can chamber a .223/5.56 into a 300 barrel. if you did and fired it who knows what would happen as it bounces off the sides of the barrel. also if you are shooting suppressed it might be a good way to damage the suppressor also. there have been some pics of people loading 300 into a .223/5.56 gun with bad consequences also.


Is the case that much shorter that it would fit into a .223 chamber? Otherwise I cannot imagine a .300 bullet fitting into the front of a .223 chamber.


I think he means shooting 300BLK in a 5.56 suppressor......there's a pic of an M4-2000 that had a couple 300BLK rounds that tried to squeeze through......looked like an expensive "oopsie"


There have been a couple of long threads about the possibility of shooting one round through the other gun. It has been demonstrated (painfully) that you can chamber and fire a 300 BLK round in a 5.56 gun. It's only possible with significant bullet setback on chambering, but it can happen. It has also been demonstrated that you CANNOT chamber and fire a .223 round in a 300 BLK gun. The bolt will not close fully so it can't go into battery and therefore the firing pin cannot strike the primer. I was VERY happy with this since my dad tried it for real (accidentally) and the gun would not fire even though the hammer did fall.


That is what I was wondering since the bullet should not fit the front of a .223 chamber, but if set back be held behind the narrow portion of the chamber and the bolt still close.
JC10311  [Team Member]
11/28/2012 4:19:14 PM
Here's one of the long threads with pictures and videos.

300 BLK in 5.56 gun
Tommy_G  [Member]
11/28/2012 4:39:14 PM
Barrel, upper receive and muzzle brake are ordered. Time to figure out what I want for hand guards and gas block.

Anyone have a set of headspace gauges for the 300?
ErikO  [Team Member]
11/28/2012 4:56:03 PM
In stock in 2-3 weeks: http://www.midwayusa.com/product/196624/ptg-headspace-go-gage-300-aac-blackout-762x35mm

Hornady and Lee make dies (H is .300 Whisper, but those will work in a 300BLK barrel just fine) that are <$40

Keep your 5.56 LC brass, that can be cut down and used for 300BLK just fine.

I plan on casting 114gr .308 gas checked spitzers when I get my upper built.
ws-6  [Team Member]
11/28/2012 5:25:47 PM
Originally Posted By RJTCCW:
Originally Posted By ws-6:
just have a good plan to keep your .223/5.56 and 300 seperate. both use the same mags, lowers, bolt, etc. you can chamber a .223/5.56 into a 300 barrel. if you did and fired it who knows what would happen as it bounces off the sides of the barrel. also if you are shooting suppressed it might be a good way to damage the suppressor also. there have been some pics of people loading 300 into a .223/5.56 gun with bad consequences also.


Is the case that much shorter that it would fit into a .223 chamber? Otherwise I cannot imagine a .300 bullet fitting into the front of a .223 chamber.


there is a thread somewhere that someone chambered a 300 in a 5.56 gun (the bullet set back into the case fully), and fired it blowing a lot of stuff up (and the bullet left the barrel).

i will say there is a way to make 5.56 fire out a of a 300 but it would be much harder (say stuck firing pin or the likes).
glk34  [Member]
11/28/2012 11:01:33 PM
Originally Posted By ws-6:
Originally Posted By RJTCCW:
Originally Posted By ws-6:
just have a good plan to keep your .223/5.56 and 300 seperate. both use the same mags, lowers, bolt, etc. you can chamber a .223/5.56 into a 300 barrel. if you did and fired it who knows what would happen as it bounces off the sides of the barrel. also if you are shooting suppressed it might be a good way to damage the suppressor also. there have been some pics of people loading 300 into a .223/5.56 gun with bad consequences also.


Is the case that much shorter that it would fit into a .223 chamber? Otherwise I cannot imagine a .300 bullet fitting into the front of a .223 chamber.


there is a thread somewhere that someone chambered a 300 in a 5.56 gun (the bullet set back into the case fully), and fired it blowing a lot of stuff up (and the bullet left the barrel).

i will say there is a way to make 5.56 fire out a of a 300 but it would be much harder (say stuck firing pin or the likes).




It is impossible.. The 5.56 is way to long to the shoulder to ever be able to close the bolt on it in a .300 chamber.

.300 blk is an awesome round and if you build one stay shorter than 10". I have an 8" and love it. I had a 16 but no longer have it. Ive hunted with it for 3 seasons and have killed multiple animals with it. Deer, coyotes, and pigs. Even better is if you reload. Lots of options out there to taylor a round that best suits you and your needs.
GaryM  [Member]
11/29/2012 12:18:51 PM
I built my 300 whisper long before anyone even thought about the blackout.
It is a good round and loads of fun for the handloader. The big heavy bullets are the way to go, 220gr matchkings or the 247gr cast (castboolits website). I have killed a few deer using the 125gr Gameking too.
Adjustable gas tube will be needed to take full advantage of this round.
Suppressing one is a hoot. You can use a 9mm pistol suppressor if you like (I use a SWR Trident 9) However do not use cast through a suppressor unless you know exactly what you are doing.
Helpful websites would be
cast boolits and 300whisper.com
Good luck and have fun, this is a round that simply begs you to experiment in so many ways.
Spkr_Bldr  [Member]
11/29/2012 9:08:45 PM
Originally Posted By GaryM:
I built my 300 whisper long before anyone even thought about the blackout.
It is a good round and loads of fun for the handloader. The big heavy bullets are the way to go, 220gr matchkings or the 247gr cast (castboolits website). I have killed a few deer using the 125gr Gameking too.
Adjustable gas tube will be needed to take full advantage of this round.
Suppressing one is a hoot. You can use a 9mm pistol suppressor if you like (I use a SWR Trident 9) However do not use cast through a suppressor unless you know exactly what you are doing.
Helpful websites would be
cast boolits and 300whisper.com
Good luck and have fun, this is a round that simply begs you to experiment in so many ways.


I've been fighting the itch ... just need a little push to build one. Think I could talk you into coming down to House Springs and let me run a few through it?
JC10311  [Team Member]
11/29/2012 9:35:20 PM
Originally Posted By Spkr_Bldr:
Originally Posted By GaryM:
I built my 300 whisper long before anyone even thought about the blackout.
It is a good round and loads of fun for the handloader. The big heavy bullets are the way to go, 220gr matchkings or the 247gr cast (castboolits website). I have killed a few deer using the 125gr Gameking too.
Adjustable gas tube will be needed to take full advantage of this round.
Suppressing one is a hoot. You can use a 9mm pistol suppressor if you like (I use a SWR Trident 9) However do not use cast through a suppressor unless you know exactly what you are doing.
Helpful websites would be
cast boolits and 300whisper.com
Good luck and have fun, this is a round that simply begs you to experiment in so many ways.


I've been fighting the itch ... just need a little push to build one. Think I could talk you into coming down to House Springs and let me run a few through it?


I have a 16" that you're welcome to try, and I'm on Hwy NN near Byrnesville Rd. Gary's welcome to come on down, too.
Spkr_Bldr  [Member]
11/30/2012 12:20:26 AM
Originally Posted By JC10311:
Originally Posted By Spkr_Bldr:
Originally Posted By GaryM:
I built my 300 whisper long before anyone even thought about the blackout.
It is a good round and loads of fun for the handloader. The big heavy bullets are the way to go, 220gr matchkings or the 247gr cast (castboolits website). I have killed a few deer using the 125gr Gameking too.
Adjustable gas tube will be needed to take full advantage of this round.
Suppressing one is a hoot. You can use a 9mm pistol suppressor if you like (I use a SWR Trident 9) However do not use cast through a suppressor unless you know exactly what you are doing.
Helpful websites would be
cast boolits and 300whisper.com
Good luck and have fun, this is a round that simply begs you to experiment in so many ways.


I've been fighting the itch ... just need a little push to build one. Think I could talk you into coming down to House Springs and let me run a few through it?


I have a 16" that you're welcome to try, and I'm on Hwy NN near Byrnesville Rd. Gary's welcome to come on down, too.


I wouldn't mind trying a 16 incher, but it's a suppressed SBR that has me interested. Weekdays are better than weekends for me. Anything you've been wanting to try, I might have one or two
JC10311  [Team Member]
11/30/2012 8:39:26 AM
Me, too on the suppressed SBR. I have a10.5" barrel ordered that's supposed to show up on Monday. I need to get the gas tube, block and hand guard to complete the gun. I'm always interested in "interesting" things. I have ARs in 5.56, 300 BLK, and 7.62X39 (all 16" or longer) and just a few other guns. The range here goes out to 300 yards for those so inclined.

ETA: I work from home on Fridays and can always find time for a break to go play. Generally, I'm off on Mondays, bt this coming Monday I need to be in the office. I am home today.
bwideman  [Team Member]
11/30/2012 9:14:02 AM
Originally Posted By JC10311:
Me, too on the suppressed SBR. I have a10.5" barrel ordered that's supposed to show up on Monday. I need to get the gas tube, block and hand guard to complete the gun. I'm always interested in "interesting" things. I have ARs in 5.56, 300 BLK, and 7.62X39 (all 16" or longer) and just a few other guns. The range here goes out to 300 yards for those so inclined.

ETA: I work from home on Fridays and can always find time for a break to go play. Generally, I'm off on Mondays, bt this coming Monday I need to be in the office. I am home today.


I had this one out last time with the SDN6 on it. Next get together I'll bring it again and you guys are welcome to play.

TVLL62CAL  [Team Member]
11/30/2012 10:31:07 AM
Ok, so I think it's just me, but I cant get excited about this cartridge, somebody explain what I am missing, from what i can gather it has a few hunting applications...maybe...but not very impressive after that, is it just that you get a 30 cal in an AR w/o a bolt and mag change? if thats really at the heart of it...meh.....now a 6.8....love them
EaZeNuTZ33  [Team Member]
11/30/2012 10:45:48 AM
Originally Posted By TVLL62CAL:
Ok, so I think it's just me, but I cant get excited about this cartridge, somebody explain what I am missing, from what i can gather it has a few hunting applications...maybe...but not very impressive after that, is it just that you get a 30 cal in an AR w/o a bolt and mag change? if thats really at the heart of it...meh.....now a 6.8....love them


6.8 fan boys dont have the mental capacity to fully comprehend the awesomeness that is 300BLK/Whisper/WTF


Heres the skinny......220gr subsonic pills through a silencer, and quieter than an MP5 with 147gr 9mm.......OR......load up 110gr VMax bullets.......OR load anything between. Function remains 100% without changing gas tubes, barrels, gas settings,......


AND you can also use the same mags, BCG.....

AND brass can be cheaply had by converting your 556 brass. Since pressures are lower, especially in subsonic use, you could feasibly use brass that was already reloaded 3-4 times and cut it at the shoulder.




By merely having an upper set up in 300BLK........you can convert your brass inexpensively, use pistol powder, easily obtained 30 cal bullets, and the same primers you use for .223 to reload up some ammo anytime you want.






Compare to 6.8:
-more expensive ammo
-more expensive brass
-less utilized projectiles....could get harder to find compared to a NATO caliber (not that it is right now)
-marginal improvement in performance
-different BCG
-different mags
-arguably different lower now that LWRC is optimizing a lower and magpul is making mags to match it
-still have to use a 30cal opening in brakes and flash hiders, just like 300BLK
-more difficult to reliably run subsonic ammo without more drastic changes
JC10311  [Team Member]
11/30/2012 11:10:17 AM
You missed the most important advantage . . .




All the cool kids have one and you don't.

I struggled really hard with the decision between 6.5 Grendel, 6.8 SPC II and 300 BLK. For me it came down to this:

1. I want a gun that shoots bigger/heavier bullets than 5.56 because I believe that the heavier bullet will have more knock down power. (Not intending to start an argument here.)
2. I want a gun that shoots a commonly available round, so finding them if SHTF is less of an issue. The 300 BLK can be made from 5.56/.223 cases with minimal work, so I'll give it a point.
3. I want to have a wide range of bullet weight options with good availability. There are few calibers that fit this requirement better than the 7.62 / .308.
4. I'd like replacement parts that wear/break to be commonly available. Since the 300 BLK uses the same bolt as the .223, +1 there.
5. I want something for hunting medium-sized game (deer, 'yotes, and zombies) at my typical rages (less than 200 yards). I have real hunting rifles for bigger game at longer ranges.
6. I'm going to fantasize about having a gun that's reliable with and without a suppressor (which I don't have).

When I added up all the points, the 300 BLK won.
TVLL62CAL  [Team Member]
11/30/2012 11:50:43 AM
Originally Posted By JC10311:
You missed the most important advantage . . .




All the cool kids have one and you don't.

I struggled really hard with the decision between 6.5 Grendel, 6.8 SPC II and 300 BLK. For me it came down to this:

1. I want a gun that shoots bigger/heavier bullets than 5.56 because I believe that the heavier bullet will have more knock down power. (Not intending to start an argument here.)
2. I want a gun that shoots a commonly available round, so finding them if SHTF is less of an issue. The 300 BLK can be made from 5.56/.223 cases with minimal work, so I'll give it a point.
3. I want to have a wide range of bullet weight options with good availability. There are few calibers that fit this requirement better than the 7.62 / .308.
4. I'd like replacement parts that wear/break to be commonly available. Since the 300 BLK uses the same bolt as the .223, +1 there.
5. I want something for hunting medium-sized game (deer, 'yotes, and zombies) at my typical rages (less than 200 yards). I have real hunting rifles for bigger game at longer ranges.
6. I'm going to fantasize about having a gun that's reliable with and without a suppressor (which I don't have).

When I added up all the points, the 300 BLK won.


This is actually a more logical assessment than the previous post, fwiw I understood ALL but one of of EZ's statements and that was a "marginal" improvement in performance....and as an FFL/ SOT I have all the quiet guns I want so suppressed wasn't a factor for me, while intriguing as a new upstart the Grendel has yet to be proved overall, and as for LWRCI and their Six8, it is well understood that the lack standardization of the caliber and gun is accepted in some circles, much like AR 308 started out and to some degree still is with the lower configs...... you may have convinced me to take another look
EaZeNuTZ33  [Team Member]
11/30/2012 11:58:21 AM
Originally Posted By TVLL62CAL:
Originally Posted By JC10311:
You missed the most important advantage . . .




All the cool kids have one and you don't.

I struggled really hard with the decision between 6.5 Grendel, 6.8 SPC II and 300 BLK. For me it came down to this:

1. I want a gun that shoots bigger/heavier bullets than 5.56 because I believe that the heavier bullet will have more knock down power. (Not intending to start an argument here.)
2. I want a gun that shoots a commonly available round, so finding them if SHTF is less of an issue. The 300 BLK can be made from 5.56/.223 cases with minimal work, so I'll give it a point.
3. I want to have a wide range of bullet weight options with good availability. There are few calibers that fit this requirement better than the 7.62 / .308.
4. I'd like replacement parts that wear/break to be commonly available. Since the 300 BLK uses the same bolt as the .223, +1 there.
5. I want something for hunting medium-sized game (deer, 'yotes, and zombies) at my typical rages (less than 200 yards). I have real hunting rifles for bigger game at longer ranges.
6. I'm going to fantasize about having a gun that's reliable with and without a suppressor (which I don't have).

When I added up all the points, the 300 BLK won.


This is actually a more logical assessment than the previous post, fwiw I understood ALL but one of of EZ's statements and that was a "marginal" improvement in performance....and as an FFL/ SOT I have all the quiet guns I want so suppressed wasn't a factor for me, while intriguing as a new upstart the Grendel has yet to be proved overall, and as for LWRCI and their Six8, it is well understood that the lack standardization of the caliber and gun is accepted in some circles, much like AR 308 started out and to some degree still is with the lower configs...... you may have convinced me to take another look


I was being facetious....

ya does whats ya can..... .308 still has that problem IMO, enough of one that Armalite actually makes a DPMS pattern rifle now, correct?

All the calibers fill a role IMO. 6.8 is a great round plagued by lack of standardization. Hopefully LWRC's open source attitude on the design changes will help correct that some.

The "marginal" improvement in performance from 300BLK to 6.8 is due to energy when comparing comparable loads. The 6.8 does have the edge, but not by the margin the die hard 6.8 guys claim....at least from the numbers I have seen.



As for 6.5 Grendel....seems to be a lot of potential for long range, and I wouldn't mind having one, but I'm not overly eager to jump on one considering my .308 does well at the ranges I have available (~1/2 mile).
TVLL62CAL  [Team Member]
11/30/2012 1:13:52 PM
Originally Posted By EaZeNuTZ33:
Originally Posted By TVLL62CAL:
Originally Posted By JC10311:
You missed the most important advantage . . .




All the cool kids have one and you don't.

I struggled really hard with the decision between 6.5 Grendel, 6.8 SPC II and 300 BLK. For me it came down to this:

1. I want a gun that shoots bigger/heavier bullets than 5.56 because I believe that the heavier bullet will have more knock down power. (Not intending to start an argument here.)
2. I want a gun that shoots a commonly available round, so finding them if SHTF is less of an issue. The 300 BLK can be made from 5.56/.223 cases with minimal work, so I'll give it a point.
3. I want to have a wide range of bullet weight options with good availability. There are few calibers that fit this requirement better than the 7.62 / .308.
4. I'd like replacement parts that wear/break to be commonly available. Since the 300 BLK uses the same bolt as the .223, +1 there.
5. I want something for hunting medium-sized game (deer, 'yotes, and zombies) at my typical rages (less than 200 yards). I have real hunting rifles for bigger game at longer ranges.
6. I'm going to fantasize about having a gun that's reliable with and without a suppressor (which I don't have).

When I added up all the points, the 300 BLK won.


This is actually a more logical assessment than the previous post, fwiw I understood ALL but one of of EZ's statements and that was a "marginal" improvement in performance....and as an FFL/ SOT I have all the quiet guns I want so suppressed wasn't a factor for me, while intriguing as a new upstart the Grendel has yet to be proved overall, and as for LWRCI and their Six8, it is well understood that the lack standardization of the caliber and gun is accepted in some circles, much like AR 308 started out and to some degree still is with the lower configs...... you may have convinced me to take another look


I was being facetious....

ya does whats ya can..... .308 still has that problem IMO, enough of one that Armalite actually makes a DPMS pattern rifle now, correct?

All the calibers fill a role IMO. 6.8 is a great round plagued by lack of standardization. Hopefully LWRC's open source attitude on the design changes will help correct that some.

The "marginal" improvement in performance from 300BLK to 6.8 is due to energy when comparing comparable loads. The 6.8 does have the edge, but not by the margin the die hard 6.8 guys claim....at least from the numbers I have seen.



As for 6.5 Grendel....seems to be a lot of potential for long range, and I wouldn't mind having one, but I'm not overly eager to jump on one considering my .308 does well at the ranges I have available (~1/2 mile).


I get it, but the 6.8 like the Grendel have a much better transonic crossover distance than the 300, I think a lot of people believe the 300 will perform like the 6.8 without a lot of compromise in the system, truthfully much like the 6.5 CM or the 6.5x55 while unimpressive on paper they are VERY impressive on target , I may make the leap of faith and build a 300 for the hell of it, Noveske bbls are available from one of my suppliers.
EaZeNuTZ33  [Team Member]
11/30/2012 1:31:03 PM
Ya......I've shot 300BLK to 400yards, but don't intend to shoot beyond that. The 6.x bullets definitely handle the distance better for sure. All depends upon your purpose for the rifle/cartridge. I have no intention on shooting my 8" 300BLK beyond 150-200yards with either super or sub sonic ammo.
ErikO  [Team Member]
11/30/2012 2:10:00 PM
IF I go bigger than .308 it'll be .50 Beowolf.
GaryM  [Member]
11/30/2012 10:29:08 PM
Originally Posted By JC10311:
Originally Posted By Spkr_Bldr:
Originally Posted By GaryM:
I built my 300 whisper long before anyone even thought about the blackout.
It is a good round and loads of fun for the handloader. The big heavy bullets are the way to go, 220gr matchkings or the 247gr cast (castboolits website). I have killed a few deer using the 125gr Gameking too.
Adjustable gas tube will be needed to take full advantage of this round.
Suppressing one is a hoot. You can use a 9mm pistol suppressor if you like (I use a SWR Trident 9) However do not use cast through a suppressor unless you know exactly what you are doing.
Helpful websites would be
cast boolits and 300whisper.com
Good luck and have fun, this is a round that simply begs you to experiment in so many ways.


I've been fighting the itch ... just need a little push to build one. Think I could talk you into coming down to House Springs and let me run a few through it?


I have a 16" that you're welcome to try, and I'm on Hwy NN near Byrnesville Rd. Gary's welcome to come on down, too.


I would love to but situations dictate otherwise right now. I will explain in about a month or so.
Anyway, the short case of the 300 WTF (Whisper, Two two three- three hundred, Fireball) in the magazine made for the longer .223 allows for very long and heavy bullets. This is where the 300WTF shines. It was developed as a long range silhouette gun (look at the retained energy at long distances and also momentum figures) It ended up as an ideal candidate for suppressed rounds using these same heavy bullets.
BTW, these bullets also tumble when entering flesh and are quite effective is damaging tissue.

ETA, why the 300 blackout....
Because no one ever came up with a saami standard for the round. AAC took the cartridge, change a few small things then applied to saami for a recognition. Next thing you know everyone wants a new fangled blackout and all the old timers are saying WTF, this is all old news.
AAC has a lot of followers and a lot of detractors for this and other situations.
eric10mm  [Moderator]
12/1/2012 10:42:31 AM

Originally Posted By JC10311:

I struggled really hard with the decision between 6.5 Grendel, 6.8 SPC II and 300 BLK.
They are different tools for different jobs. The 6.5 Grendel is going to VASTLY outperform either of the other rounds, as well as 5.56, at longer distances. However at closer CQB distances the 6.8 & .300 loads with their heavier bullets are going to work very well at imparting much more knockdown power to the target, arguably better than the venerable 5.56.

OTOH, I can buy 5.56/.223 at every Walmart and sporting goods store that carries gun stuff.
GaryM  [Member]
12/1/2012 6:35:15 PM
For a bit of fun go to the beartooth bullets website and have a look at their ballistic calculators. Run the number through the thornhill, FtLbs and TKO calculators. Very interesting results.
SUB_MG  [Team Member]
12/1/2012 7:08:49 PM
I'm a big fan of the 6.8 for short barrel use with a suppressor. The faster burning poweder doesn't give up as much as the 5.56 with the shorter barrels. I also love the 300BLK with an 8" barrel suppressed but I typically only use it with subsonic ammo. Almost as quiet as my suppressed 22LR. I would take my 6.8 for most applications beyond 100 yds out to 308 range.