Is an 8-inch 308 or 12-inch 6.5Cr build possible? Accurate out to 500 yards?

LilGucci

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6.5 (SnipersHide.png



What are the drawbacks of a short-barrel 308 and 6.5 Creedmoor? I'm talking 7"-9" 308, and 7"-12" 6.5 Creedmoor. (I can't find barrel lengths shorter than 12" for 6.5 Creedmoor.)

I want to do short-barrel pistol builds with a PDW type stock seen on the Honey Badger / Ghetto Blaster, using JP Enterprises AR-10 H2 Heavy Silent Capture Springs.

I mostly want a fun gun to shoot suppressed, and unlike the 300 Blackout, 1moa or less out to 500 - 600 yards. (Min-Max) I don't mind shooting them unsuppressed either, so long as noise levels are tolerable with ear protection.

I've heard that gas systems with such short barrels on 308, especially suppressed, will wear the bolt/pin out very quickly, and I don't know if such guns can be as soft-shooting as a suppressed 300 Blackout setup.

Is there a ton of powder that is not yet burnt up before 10 inches of barrel length and how much barrel is needed for those two calibers to be accurate at 500 yards?

Will 6.5 Creedmoor be softer shooting? And at what cost? Is it a faster bullet, and will it be louder out the muzzle than the heavier slower 308, especially at these lengths? Or is a 308 more ideal for such a fun-gun setup. Would the 308, subsonic and suppressed, be closer to a 300 Blackout build than the 6.5?

And yes, I know the 6.5 Grendal exists, and I will get one a couple of years from now. Just a fun little experiment with two fun guns I hope to build.
 
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chevy_man

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It's more a question of why?

Extreme muzzle blast without the can, extreme wear on the blast baffle of a can.

I would imagine the velocity is quite piss poor.

The gas system is going to be absolutely violent. I wouldn't plan on being about to get many reloads out of brass.

I'd imagine it would be blinding at night. Hell, look at the fireballs you get with 7.62x39 out of an Ak pistol.
 

Anb618

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There’s guys building .308 R700 “pistols” in the 10” range with Black Collar Arms chassis. Seems like what I’ve seen has been positive, you just can’t expect to get any velocity.
 
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Dan M

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Suppressed with full power 308 rounds... not so quiet... subsonic is quiet, but not as quiet at 300 BO.Your drop at 500-600 with subsonic 308 is going to be substantial. Do your calculations... just a SWAG but I bet it will be over 100" at 500 yards.
 
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deersniper

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300 blackout can be loaded very accurately.

You are asking for unenjoyable muzzle blast and concussion. A 9" 223 is bad enough.

image.jpg

Oh and your cans will have short lived
 

LilGucci

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300 blackout can be loaded very accurately.

You are asking for unenjoyable muzzle blast and concussion. A 9" 223 is bad enough.

Oh and your cans will have short lived

What about with the 6.5 Creedmoor?

How short a barrel can I go with subsonic ammo in 6.5 and 308, and still have reasonable recoil, muzzle blast, sound, either suppressed or un-suppressed while shooting accurately out to 300 yards, sub-moa?
 

LilGucci

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It's more a question of why?

Extreme muzzle blast without the can, extreme wear on the blast baffle of a can.

I would imagine the velocity is quite piss poor.

The gas system is going to be absolutely violent. I wouldn't plan on being about to get many reloads out of brass.

I'd imagine it would be blinding at night. Hell, look at the fireballs you get with 7.62x39 out of an Ak pistol.

Is this the same for the 6.5 Creedmoor? Or would it be worse for the 6.5?
 

LilGucci

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Just build them and do range reports. I doubt very seriously anyone has built an 8” 308 around here. I have built a 12.5” 308 and I can assure you it’s NOT as soft shooting as a 300 Blackout!!! 😂
Geez, you're killing my dreams lol

What's a caliber larger than 300 blackout that would be perfect for a SBR/Pistol type build with similar subsonic short-barrel qualities to 300 blackout, except you can shoot it out to about 500 yards with 1" moa or less? I just need a small PDW that can shoot past 300 yards with sub moa at a barrel length of 12" or less, preferably 9" barrel or less.
 

AIAW

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Geez, you're killing my dreams lol

What's a caliber larger than 300 blackout that would be perfect for a SBR/Pistol type build with similar subsonic short-barrel qualities to 300 blackout, except you can shoot it out to about 500 yards with 1" moa or less? I just need a small PDW that can shoot past 300 yards with sub moa at a barrel length of 12" or less, preferably 9" barrel or less.
1573008951397.gif

The trick is TrailBoss... lots of TrailBoss... 😳
 

sea2summit

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6.5 G in a 12.5” has been reportedly very accurate out to 7-800ish. Not sure you’d gain much by 6.5 C out of that barrel length other than a heavier bullet maybe.
 
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LilGucci

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You do realize that a 200 grain bullet at 1000fps from a 308 is the same as a 200 grain bullet at 1000fps from a 300 blackout right? There seems to be some holes in your knowledge of both ballistics and gas gun operation.
Yeah I just got into guns this year, thanks to my neighbors, family, friends, and social media/youtube.

Bought my first few guns in the first half of this year and now I've just gotten into building guns in the second half of this year.

I'm brand new to all of this, but I wanted to build one "Instagram/Gucci" gun before I got underway with my more serious, survival and/or PRS/3-gun projects. I'm still learning, the very basics of firearms and distance shooting.
 

AIAW

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Yeah I just got into guns this year, thanks to my neighbors, family, friends, and social media/youtube.

Bought my first few guns in the first half of this year and now I've just gotten into building guns in the second half of this year.

I'm brand new to all of this, but I wanted to build one "Instagram/Gucci" gun before I got underway with my more serious, survival and/or PRS/3-gun projects. I'm still learning, the very basics of firearms and distance shooting.
Genuinely, you get points for saying that straight-up instead of pretending to already know everything. 👍
 

LilGucci

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6.5 G in a 12.5” has been reportedly very accurate out to 7-800ish. Not sure you’d gain much by 6.5 C out of that barrel length other than a heavier bullet maybe.
Wow, this sounds exciting! Maybe I'll do a 9-inch 6.5 Grendal pistol! I don't need it to hit out to 700 yards.
 

TonyTheTiger

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Well to start with, are you wanting to shoot supersonic and subs? Because you're asking to much of a cartridge the size of 308/6.5CM to work in a gas gun at both ends of the spectrum, especially in such short barrels. If you're only shooting subs, 308/6.5CM have no reason to be in this conversation. And you'll find subs past 300 yards very unsatisfactory.
Basically your requirements are too broad, you can't have a PDW, battle rifle, sniper rifle and gas operation all in one gun.
 
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LilGucci

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Well to start with, are you wanting to shoot supersonic and subs? Because you're asking to much of a cartridge the size of 308/6.5CM to work in a gas gun at both ends of the spectrum, especially in such short barrels. If you're only shooting subs, 308/6.5CM have no reason to be in this conversation. And you'll find subs past 300 yards very unsatisfactory.
Basically your requirements are too broad, you can't have a PDW, battle rifle, sniper rifle and gas operation all in one gun.
Well that makes sense, certainly more sense than my Gucci/Instagram gun project. I was just thinking of building at least one 308 or 6.5 Creedmoor in a pistol/SBR package that would be fun suppressed and still cool unsuppressed like the guns in the pictures I posted above.

I'm liking the idea of a 12-inch 6.5 Grendel a lot better though, because I don't want a second 300-blackout build, and having another gun like my 300-blackout that can shoot out to 4-500 yards with 1moa or less would be awesome.
 

346ci

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I shoot a 12.5" 6.8 as my main deer rifle. It's been out to 400yds on steel, easy and fun.

That is going to be one of your best options for a SBR, I'd build another way before a super short flash bang 308/Creedmoor.
 
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deersniper

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Just build a blackout. Or buy one. There's a sweet radian arms upper for sale in the classifieds. I would buy it if I didn't have a bunch already.

I can hit sub ispc targets at 580 with supers. 12" plate at 300 is super easy with subs. Can hit a lot farther away than that too.

I use a dedicated leupold black or scope with drops for both subs and supers. But if your prefer accuracy over speed, a ffp NF 1-8 or 2.5-20 or 4-14 would be ideal also
 
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Darqusoull13

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@LilGucci If you're wanting something to cycle forget it. You're going to waste time on a 10" or under large frame 308 / 6.5 Creed. You're far better off running a 300 BLK or a 12.5 Grendel if you want something that short to cycle.

Buuuuuut...
A really fun option for shooting subsonic to utilize your current plan would be to follow the black pistol build idea and make a straight pull pistol build. This setup has no gas system and was meant to be a handy deer rifle. Essentially if you're hot about doing a very short barrel in a large frame AR upper, this is something that might fit.

Unless you plan on having a 2nd upper I would prefer to go the route of the green pistol or something similar.

*ETA - Grendel Shorty
StraightPull.jpgpistol.png
 
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sea2summit

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People keep saying 300 BO, did they miss the 500 yard requirement?

In real life I’ve had horrible experience with 300BO killing things. I wanted it to work so bad I stuck with it way longer than I should have. Fun to shoot, fun to suppress, but horrible at killing. Got rid of my last one earlier this summer.
 

deersniper

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I didn't see mr InstaStar say anything about killing. But Barnes black tip, and 110 vmax, and 220smk and 190 subx kill fine. Placement is more important than cartridge.

what makes you think a 10" 308 is going to be much different than a 10" blk at 500?
 
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BoilerUP

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People keep saying 300 BO, did they miss the 500 yard requirement?

In real life I’ve had horrible experience with 300BO killing things. I wanted it to work so bad I stuck with it way longer than I should have. Fun to shoot, fun to suppress, but horrible at killing. Got rid of my last one earlier this summer.
Supers or subs, and what bullet?
 

sea2summit

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Supers or subs, and what bullet?
Yes;)

Last one I used was some 135s and they were cooking at about 2150. With that round this cat took three shots (broadside, running hit again spine-ish lost use of backlegs, then center chest) from about 40m and when I got to him he was tearing the shit out of a tree and I had to put a final round in his head. That’s not okay. Also lost a fox and raccoon, fox recovered days later I think because the dogs brought a decaying fox to the house.
D41E449E-0B0A-4E62-A080-848C0D5BEE6A.jpeg

Went back to 5.56 and haven’t lost any critters. This is a chicken/goat defense rifle so I really wanted the 300 BO to work for noise and ricochet concerns for neighbors. Ohh well, live and learn.
 
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sea2summit

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I didn't see mr InstaStar say anything about killing. But Barnes black tip, and 110 vmax, and 220smk and 190 subx kill fine. Placement is more important than cartridge.

what makes you think a 10" 308 is going to be much different than a 10" blk at 500?
He didn’t say kill but did say 500. I could be wrong but I don’t think 300 can get out to 500 reliably. And I didn’t recommend a 308 SBR either.
 
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deersniper

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Yes;)

Last one I used was some 135s and they were cooking at about 2150. With that round this cat took three shots (broadside, running hit again spine-ish lost use of backlegs, then center chest) from about 40m and when I got to him he was tearing the shit out of a tree and I had to put a final round in his head. That’s not okay. Also lost a fox and raccoon, fox recovered days later I think because the dogs brought a decaying fox to the house.
View attachment 7178225

Went back to 5.56 and haven’t lost any critters. This is a chicken/goat defense rifle so I really wanted the 300 BO to work for noise and ricochet concerns for neighbors. Ohh well, live and learn.
You used a non expanding / non easily fragmenting bullet in a low-mid velocity cartridge. On a thin skinned light animal.

Black tips, or 125 tmks or a Lehigh bullet would have been a different story.

And yes. You can shoot well past 500 with a blk.

How do you like the t50?
 

sea2summit

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You used a non expanding / non easily fragmenting bullet in a low-mid velocity cartridge. On a thin skinned light animal.

Black tips, or 125 tmks or a Lehigh bullet would have been a different story.

And yes. You can shoot well past 500 with a blk.

How do you like the t50?
I acknowledge they were all light skin/weight animals but that wasn't the only ammo I used, just the worst example. But at the same time only one of those three shots was a passthrough so there's that. Seven animals, only one was DRT and that was enough for me to move on. Like I said, I wanted it to work for the purpose but it didn't seem to want to and I wasn't going to invest in rolling my own so YMMV but I'm never touching it again.

I like the T50 a lot, needs to go back in for recollimation but I use it stand alone 90% of the time so it's not a high priority. If you are putting it infront of an optic it gets really heavy really fast so stationary it's fine but on the move not so much if used infront of something.
 

deersniper

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Did you ever try the 110 Vmax?
I bought a bunch of them loaded in American gunner. Have not used them yet. Saw a test on the 300blk forum or ar15.com that showed 0-minimal expansion :(. Looks like black tip Barnes, or black hills 125 tmk is the way to go for super. But $$$$
The hornady sub x load works well for subsonic.
 

deersniper

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I acknowledge they were all light skin/weight animals but that wasn't the only ammo I used, just the worst example. But at the same time only one of those three shots was a passthrough so there's that. Seven animals, only one was DRT and that was enough for me to move on. Like I said, I wanted it to work for the purpose but it didn't seem to want to and I wasn't going to invest in rolling my own so YMMV but I'm never touching it again.

I like the T50 a lot, needs to go back in for recollimation but I use it stand alone 90% of the time so it's not a high priority. If you are putting it infront of an optic it gets really heavy really fast so stationary it's fine but on the move not so much if used infront of something.
I see. I agree with you about 223. Works better than most give it credit for.

Do you have contact for the Flir calibration.? I have 2 and both are off 1-3" when used as clip on and they don't have internal reticles. Did not know about either of those issues when I bought them. Thanks.
 

sea2summit

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I see. I agree with you about 223. Works better than most give it credit for.

Do you have contact for the Flir calibration.? I have 2 and both are off 1-3" when used as clip on and they don't have internal reticles. Did not know about either of those issues when I bought them. Thanks.
FLIR I guess only works through their dealers, I talked to TNVC and they said they'd handle it. Can't remember what the cost was but it was enough that I decided I didn't need it that bad:censored:
 
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sam4886

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If you're looking for Gucci, do a 375 socom on a piston upper. 8-10 inches is all you need. It'll get to 500, but accuracy is more on the barrel, ammo, and shooter quality.

Slap a can on and have it cerakoted something rediculous and be the star of reddit for a day.
 
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padom

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300blk has no problems out to 500yds for punching paper or banging steel. I wouldnt be killing anything with it @ 500yd...

I can go 10/10 on steel @ 200, 300, 400 and 500yd with my 10.5" Ultramatch 300blk using my 125TMK handloads @ 2100fps. This is a half MOA gun @ 100yds and submoa out to 500yds.


 
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deersniper

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Re: 300 blk 110 vmax
Here's the links. First the old one which looks like used slower off brand ammo.then the second one which sounds positive. Have not read through it yet.


 
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deersniper

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If you're looking for Gucci, do a 375 socom on a piston upper. 8-10 inches is all you need. It'll get to 500, but accuracy is more on the barrel, ammo, and shooter quality.

Slap a can on and have it cerakoted something rediculous and be the star of reddit for a day.
Lol you jogged my memory.

Do 8.6 creedmoor. Seriously. It's 300 blk but bigger.

 
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softcock

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Wow, this sounds exciting! Maybe I'll do a 9-inch 6.5 Grendal pistol! I don't need it to hit out to 700 yards.
-
Just buy AK74 krinkov folder 5.45x39, and have the world by the nuts and be done with it .
.
 
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LilGucci

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@LilGucci If you're wanting something to cycle forget it. You're going to waste time on a 10" or under large frame 308 / 6.5 Creed. You're far better off running a 300 BLK or a 12.5 Grendel if you want something that short to cycle.

Buuuuuut...
A really fun option for shooting subsonic to utilize your current plan would be to follow the black pistol build idea and make a straight pull pistol build. This setup has no gas system and was meant to be a handy deer rifle. Essentially if you're hot about doing a very short barrel in a large frame AR upper, this is something that might fit.

Unless you plan on having a 2nd upper I would prefer to go the route of the green pistol or something similar.

*ETA - Grendel Shorty
View attachment 7178177View attachment 7178181
That black JP SBR is absolutely gorgeous! And thank you, I might just skip this little project altogether and go with an SBR bolt-action rifle like I posted above, a 300blackout 5-inch pistol, and a 12-inch 6.5 Grendel. I think that'll work the best for me. So sad 6.5 Creedmoor wouldn't be able to overcome the limitations of the 308 caliber.
 

LilGucci

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Just buy AK74 krinkov folder 5.45x39, and have the world by the nuts and be done with it .
.
Unfortunately, and it is unfortunate, but I just don't like AK's. I'm still going to try to get the SLR106 from Arsenal in 556, and customize it but I've just never had a love for that gun. Reliable, and/but primitive in eyes. Hopefully someone can change that in the future.