Looking to build a .30 cal AR

15plus1 · October 23, 2017, 04:31 PM

Hi folks,

I'm interested in building an AR-15. I have a factory retro at this time ('Nam era best as I can figure) that I don't want to use the lower from, so I will be starting from scratch. As I already have a 5.56, in a rifle length platform, I was looking for something a little smaller but I don't want to get into SBRs just yet.

.30 cal range is what I am thinking on, with 16" barrel, and intended for short to medium range. I thought about simply doing an AR-10, but was thinking that parts are less readily available and more expensive, but also that a shorter barrel for .308 might not be using the round to its capability.

So it seems I'm looking at .300 blackout and 7.62×39. The latter is thus far seeming like the more attractive option due to ammunition availability and cost. I have no plans to do and SBR or supress, so again a .300 blackout build might not be best for me.

So, I guess my question would be, have all the functionality bugs been worked out of 7.62 for the AR? I am wary of locking into something previously known to be troublesome, as I don't necessarily have the funding to continuously replace parts and tinker.

I don't really want to have my rifle built for me, but is there a combination of components that are basically guaranteed to work together?

bfoosh006 · October 23, 2017, 05:08 PM

7.62x39...

The biggest hiccup is the mags for a tradtional AR15. ...still are and always will be.... not to mention the Bolt... the thin walls can break lugs easier then typical.

I would stick with a tried and true AK.

For me the only way I would do 7.62x39 in an "AR".. is this..

http://palmettostatearmory.com/psa-1...mod-rifle.html

300BK ... is the way to go... plenty of very respectable parts and conventional AR's... and still retains the ability to change uppers readily.

Ammo isn't as cheap... but the bullet designs can be state of the art and very effective.

CarJunkieLS1 · October 23, 2017, 06:10 PM

.30 Caliber AR-15 Look No Further than the .30 Sabercat or find yourself a used .30 Rem AR.

ed308 · October 23, 2017, 07:04 PM

What do you want to do with it? I mean, if you are planning on running suppressed at a range up to 100 yards, then the BO is perfect for that role. Outside of those parameters, there's better choices. The x39 can be difficult to run and feed and hard on bolts in an AR. The .30 Sabercat is nice, but it's a wildcat and you'll still need to make your brass.

IMO, there's no "great" choices when it comes to .30 cal in the AR15. That's due to the limitations of the size of the magwell. The 30 Rem was probably the best for the AR, but Remington screwed up that cartridge like so many others it touched. That 16" AR10 you were thinking about, it will certainly out perform most of the ones mention. If weights not factor, might as well go with an AR10. But you'll have to deal with a heavier AR and more recoil. Aero, Palmetto, DPMS, Armalite and others make AR10s worthy of you consideration. Or better yet, build a 16" .223/5.56 AR, 6.8 AR or 6.5 Grendel. There's a reason why they're so popular in a AR15. They all perform great in the AR15.

Sharkbite · October 23, 2017, 07:25 PM

I run a 300blk pretty much exclusively now. With a 16” barrel running 110/125gn supersonic ammo it will do anything you should do with an AR-15.

All the same parts as a 223/556 gun, except the barrel. Mags and bolts were the big problem with 7.62x39. Not an issue with the 300blk

Stats Shooter · October 23, 2017, 08:28 PM

AR's were designed around the .308 and 223. In fact Stoners first design was a .308. why bring this up? Because every thing else has to undergo some modifications to work. The .300 BO not withstanding as it is a .223 case.

Anyway, parts are easy to come by for both AR-10 in.308 and .223. i have two AR-10's (308). One is a Ruger SR 762 w/16" chrome lined hammer forged barrel. And an AR-10T (amalite) w/ 20" barrel. I also have a .308 in a bolt action rifle.

With heavier bullets, the difference between a 16" barrel and 24" barrel is about 200 fps. The difference between my 20" and 16" is about 130 fps. So beyond 20", the marginal benefit per inch is low. My loads with 175 gr smk's perform well in all 3. But the 16" is easier to load for because the short fluted barrel harmonics vary less with different hand loads. The same will be true with factory ammo.

Also, unless you plan to go out past 600 yards, you won't miss the 200 fps unless you want a longer maximum point blank range.

With lighter bullets, the velocity difference between 16, 20, and 24" barrels is greater, but the muzzle energy difference is similar to that of the heavier bullets.
Also, if you are wanting accuracy, match ammo will be easier to find in .308.

You should do your own homework on this to verify, but you will find I am right.

So, in summary, if it is for 600 or less, go 16" AR-10. If 1k yards is desired or you want more pop, go 20".... but go .308, you will be glad you did

SamNavy · October 23, 2017, 09:31 PM

https://en.wikipedia.org/wiki/List_o...tform_calibers

Since you mention ammo availability being a concern, I'll assume you're only interested in calibers where you can roll into an LGS and find some. In that case, your only AR15 rifle caliber options bigger than .223 are REALISTICALLY:
7.62x39
300blk
6.8spc
6.5 Grendel

There are dozens more production and wildcats based off the .223 and 6.8spc (30 Remington) cases. You can fit a .17 to .338 caliber bullet in a .223 case... everything has been tried already. You can squeeze up to a .358 in a 6.8spc case. I don't think this is what you're looking for though... so...

The easy answer for shooting .30 caliber bullets from an AR15 is... .300BLK. Don't beat yourself up about the "I'll never SBR or suppress"... the caliber works perfectly fine supersonic. Running a 16" barrel with supersonics through a carbine gas system is perfectly reliable. Use a standard carbine buffer and normal gas block. No need for an adjustable block. You'll want a 1:8 twist barrel shooting supers (actually, you'd want 1:10, but I don't know who makes one).

Any 110gr factory ammo with Barnes TAC-TX bullet gets you 2200'ish FPS from a 16" barrel and is good for deer and hogs out to 200yds (mind your drop).

Mobuck · October 24, 2017, 06:35 AM

300AAC/BO: Quite a bit of good accurate ammo at "reasonable" prices. Usually fairly accurate and functional. Range is limited unless you just enjoy aiming at the moon to hit your target beyond 100 yards. Effectiveness on game is questionable beyond 150 yards due to low velocities. I have 2(or maybe 3) AR uppers in this caliber and have shot both super and sub sonic ammo with and w/o suppressor. The cartridges feed through standard mags and the platform functions well if a carbine gas is used.
7.62x39: If your barrel likes Hornady V-max or SST bullets, you've got it made. Those aren't the cheapest but do perform well. Otherwise ammo is cheap and can be found everywhere but quality is ???. Effectiveness on game with Hornady SST is all you can expect from this velocity/bullet weight within 150 yards but declines significantly beyond that. The earlier bolt problems may have been addressed and the magazines I use work well. Function of the platform is good as long as bullet shape is fairly pointy w/o too much exposed lead at the point. I have 3 uppers in this caliber.
You have to make a choice: 300BO with commonality of parts, better accuracy, slightly more expensive ammo choices or 7.62x39 with specific bolt/mag issues and a plethora of cheap but often lower quality ammo.

Bartholomew Roberts · October 24, 2017, 06:56 AM

Quote:

Any 110gr factory ammo with Barnes TAC-TX bullet gets you 2200'ish FPS from a 16" barrel and is good for deer and hogs out to 200yds (mind your drop).

Using a Magnetospeed chrony, I'm getting 2170fps from factory Barnes 110gr TAC-TX in a 9" barrel and 2199fps (averages) from factory Hornady 110gr VMAX. So, I bet you'd be closer to 2350fps out of a 16" barrel, even though .300 is designed to maximize the benefit of a short barrel.

amprecon · October 24, 2017, 07:02 AM

I have been following alternative calibers for the AR for some time now and consider the pro's and con's of each. I remain loyal to the 6.8spcII in my AR's.

Chainsaw. · October 24, 2017, 07:27 AM

Just get a x39, make sure you getva quality bolt and the right mags, enjoy.

jersurf101 · October 24, 2017, 07:43 AM

I have a 5.56 ar that I but 8 years ago and a .223 axis. I wanted another A R and had bought an Aero precision lower last year. I went with 300 blackout and love it. It is a soft shooter and brass is relatively easy to convert or come by. Wally world sells 300 blk ammo. With the popularity if 6.5s projectiles are not that expensive.

The rifle is a soft shooter and very reliable for me. I went with a cbc 16" upper and a pistol length gas system

What it came down to for me is starting to standardize projectiles. With a 3006, .308, 300wsm and a 30-30 the 300 blk makes sense for me. I am currently shooting old military 150 fmj pulls over 2400. Love this rifle. Barely shoot the .556 anymore.

smee78 · October 24, 2017, 07:47 AM

I built a X39 rifle and havent really had any problems. The biggest help is the ASC mags for the X39 builds they have a better curve that helps with feeding. I built mine for hunting and have had no problems running brass or steel case ammo. Alot will depend on what you want to do with this gun, I knkw you said no sbr or cans so I guess its just for blasting at the range? Also a big help would be to know if you reload, that would help alot to negate ammo cost and would probably lead me to refer you to the 300blk.

jonnyc · October 24, 2017, 08:04 PM

Built my first AR a few months ago, in 5.56, and I've been a very happy camper. Decided to build another lower and was going to take my time thinking and deciding on an upper. A week later I already had my 300BLK all together. Went to the range yesterday and whole-heartedly confirmed I made the right choice.

stagpanther · October 24, 2017, 11:57 PM

300 BLK is a good, easy build--but has it's limits. If 30 cal out of a common AR 15 set-up is a must you're probably going to need to look at wildcats, which are going to be expensive to feed if you're not a reloader. AR15 performance is a "top gun" with 6.8 spc and he also makes a 30 harret cat based on the 6.8 case which looks very interesting to me--though, like the 300 BLK your bullet choices are likely going to be limited, them's the breaks because you're selecting a caliber for an action which was not designed for the size/length of a 30 cal.

jetinteriorguy · October 25, 2017, 05:06 AM

I bought an AR Stoner upper in 7.62x39 last year and put it on an AeroPrecision lower that I put together and it's one of my favorite rifles. With a crappy red dot it's sub 2MOA at 100 yds, I'm going to scope it and see if I can get closer to MOA. Just get the AR Stoner mags, or the ASC mags and your good. You can also use standard .223 mags as long as you limit them to 5 rounds. I can't attest to durability but I have put close to a thousand rounds down range with no issues. I also have a friend with the PSA version and his experience is pretty much the same as mine.

stagpanther · October 25, 2017, 06:22 AM

Quote:

I bought an AR Stoner upper in 7.62x39 last year and put it on an AeroPrecision lower that I put together and it's one of my favorite rifles. With a crappy red dot it's sub 2MOA at 100 yds, I'm going to scope it and see if I can get closer to MOA. Just get the AR Stoner mags, or the ASC mags and your good. You can also use standard .223 mags as long as you limit them to 5 rounds. I can't attest to durability but I have put close to a thousand rounds down range with no issues. I also have a friend with the PSA version and his experience is pretty much the same as mine.

Excellent points--pretty much if you're not going to reload a 30 cal for an AR 15 yourself--the 7.62 x 39 in an AR is probably your most bang for the buck for a 30--I bought a PSA AR47 7.62 x 39 upper for $149 and it shoots great for that ammo. I can get right around MOA at 100 with a good handload--probably could do under if I did a build with free-floated guard etc.

15plus1 · November 3, 2017, 08:47 PM

Thanks for all the input. It's still a bit to think about as I really don't have the funds to tinker much.

I think I'm enamored with the x39 in an AR because it's a little weird and not supposed to be. Ammunition availability does play a big part though. I'm not discounting the .308 Ar-10, however ammo cost plays a big part there and I have no plans to reload at this time.

I've tried the AK, and I'm not a big fan of the platform due to a few factors, but I do like the way the caliber performs as I am looking for a short range/decent power option.

Thanks to all for input and to those who were able to recommend some good parts to look into.

October 23, 2017, 04:31 PM	#1
15plus1 Member Join Date: March 5, 2017 Posts: 57	Looking to build a .30 cal AR Hi folks, I'm interested in building an AR-15. I have a factory retro at this time ('Nam era best as I can figure) that I don't want to use the lower from, so I will be starting from scratch. As I already have a 5.56, in a rifle length platform, I was looking for something a little smaller but I don't want to get into SBRs just yet. .30 cal range is what I am thinking on, with 16" barrel, and intended for short to medium range. I thought about simply doing an AR-10, but was thinking that parts are less readily available and more expensive, but also that a shorter barrel for .308 might not be using the round to its capability. So it seems I'm looking at .300 blackout and 7.62×39. The latter is thus far seeming like the more attractive option due to ammunition availability and cost. I have no plans to do and SBR or supress, so again a .300 blackout build might not be best for me. So, I guess my question would be, have all the functionality bugs been worked out of 7.62 for the AR? I am wary of locking into something previously known to be troublesome, as I don't necessarily have the funding to continuously replace parts and tinker. I don't really want to have my rifle built for me, but is there a combination of components that are basically guaranteed to work together?

October 23, 2017, 07:04 PM	#4
ed308 Senior Member Join Date: November 5, 2016 Location: DFW, TX Posts: 1,147	What do you want to do with it? I mean, if you are planning on running suppressed at a range up to 100 yards, then the BO is perfect for that role. Outside of those parameters, there's better choices. The x39 can be difficult to run and feed and hard on bolts in an AR. The .30 Sabercat is nice, but it's a wildcat and you'll still need to make your brass. IMO, there's no "great" choices when it comes to .30 cal in the AR15. That's due to the limitations of the size of the magwell. The 30 Rem was probably the best for the AR, but Remington screwed up that cartridge like so many others it touched. That 16" AR10 you were thinking about, it will certainly out perform most of the ones mention. If weights not factor, might as well go with an AR10. But you'll have to deal with a heavier AR and more recoil. Aero, Palmetto, DPMS, Armalite and others make AR10s worthy of you consideration. Or better yet, build a 16" .223/5.56 AR, 6.8 AR or 6.5 Grendel. There's a reason why they're so popular in a AR15. They all perform great in the AR15. Last edited by ed308; October 23, 2017 at 07:17 PM.

October 24, 2017, 07:02 AM	#10
amprecon Senior Member Join Date: November 5, 1999 Location: TN Posts: 786	I have been following alternative calibers for the AR for some time now and consider the pro's and con's of each. I remain loyal to the 6.8spcII in my AR's. __________________ "You can't get 'em all Josey." "That's a fact". "Well how come you doin' this then?" "Cause I got nothin' better to do."

October 24, 2017, 07:27 AM	#11
Chainsaw. Senior Member Join Date: September 12, 2015 Location: Issaquah WA. Its a dry rain. Posts: 1,774	Just get a x39, make sure you getva quality bolt and the right mags, enjoy. __________________ Just shoot the damn thing.

October 24, 2017, 07:47 AM	#13
smee78 Senior Member Join Date: July 14, 2008 Location: South Carolina Posts: 2,918	I built a X39 rifle and havent really had any problems. The biggest help is the ASC mags for the X39 builds they have a better curve that helps with feeding. I built mine for hunting and have had no problems running brass or steel case ammo. Alot will depend on what you want to do with this gun, I knkw you said no sbr or cans so I guess its just for blasting at the range? Also a big help would be to know if you reload, that would help alot to negate ammo cost and would probably lead me to refer you to the 300blk. __________________ We know exactly where one cow with Mad-cow-disease is located, among the millions and millions of cows in America, but we haven't got a clue where thousands of illegal immigrants and terrorists are

October 23, 2017, 05:08 PM	#2
bfoosh006 Senior Member Join Date: February 17, 2009 Posts: 1,089	7.62x39... The biggest hiccup is the mags for a tradtional AR15. ...still are and always will be.... not to mention the Bolt... the thin walls can break lugs easier then typical. I would stick with a tried and true AK. For me the only way I would do 7.62x39 in an "AR".. is this.. http://palmettostatearmory.com/psa-1...mod-rifle.html 300BK ... is the way to go... plenty of very respectable parts and conventional AR's... and still retains the ability to change uppers readily. Ammo isn't as cheap... but the bullet designs can be state of the art and very effective.

October 23, 2017, 06:10 PM	#3
CarJunkieLS1 Senior Member Join Date: October 1, 2013 Posts: 686	.30 Caliber AR-15 Look No Further than the .30 Sabercat or find yourself a used .30 Rem AR.

October 23, 2017, 07:25 PM	#5
Sharkbite Senior Member Join Date: November 4, 2013 Location: Western slope of Colorado Posts: 3,679	I run a 300blk pretty much exclusively now. With a 16” barrel running 110/125gn supersonic ammo it will do anything you should do with an AR-15. All the same parts as a 223/556 gun, except the barrel. Mags and bolts were the big problem with 7.62x39. Not an issue with the 300blk

October 23, 2017, 08:28 PM	#6
Stats Shooter Senior Member Join Date: August 26, 2016 Location: North Dakota Posts: 1,636	AR's were designed around the .308 and 223. In fact Stoners first design was a .308. why bring this up? Because every thing else has to undergo some modifications to work. The .300 BO not withstanding as it is a .223 case. Anyway, parts are easy to come by for both AR-10 in.308 and .223. i have two AR-10's (308). One is a Ruger SR 762 w/16" chrome lined hammer forged barrel. And an AR-10T (amalite) w/ 20" barrel. I also have a .308 in a bolt action rifle. With heavier bullets, the difference between a 16" barrel and 24" barrel is about 200 fps. The difference between my 20" and 16" is about 130 fps. So beyond 20", the marginal benefit per inch is low. My loads with 175 gr smk's perform well in all 3. But the 16" is easier to load for because the short fluted barrel harmonics vary less with different hand loads. The same will be true with factory ammo. Also, unless you plan to go out past 600 yards, you won't miss the 200 fps unless you want a longer maximum point blank range. With lighter bullets, the velocity difference between 16, 20, and 24" barrels is greater, but the muzzle energy difference is similar to that of the heavier bullets. Also, if you are wanting accuracy, match ammo will be easier to find in .308. You should do your own homework on this to verify, but you will find I am right. So, in summary, if it is for 600 or less, go 16" AR-10. If 1k yards is desired or you want more pop, go 20".... but go .308, you will be glad you did

October 23, 2017, 09:31 PM	#7
SamNavy Senior Member Join Date: August 28, 2011 Location: Virginia Beach, VA Posts: 433	https://en.wikipedia.org/wiki/List_o...tform_calibers Since you mention ammo availability being a concern, I'll assume you're only interested in calibers where you can roll into an LGS and find some. In that case, your only AR15 rifle caliber options bigger than .223 are REALISTICALLY: 7.62x39 300blk 6.8spc 6.5 Grendel There are dozens more production and wildcats based off the .223 and 6.8spc (30 Remington) cases. You can fit a .17 to .338 caliber bullet in a .223 case... everything has been tried already. You can squeeze up to a .358 in a 6.8spc case. I don't think this is what you're looking for though... so... The easy answer for shooting .30 caliber bullets from an AR15 is... .300BLK. Don't beat yourself up about the "I'll never SBR or suppress"... the caliber works perfectly fine supersonic. Running a 16" barrel with supersonics through a carbine gas system is perfectly reliable. Use a standard carbine buffer and normal gas block. No need for an adjustable block. You'll want a 1:8 twist barrel shooting supers (actually, you'd want 1:10, but I don't know who makes one). Any 110gr factory ammo with Barnes TAC-TX bullet gets you 2200'ish FPS from a 16" barrel and is good for deer and hogs out to 200yds (mind your drop).

October 24, 2017, 06:35 AM	#8
Mobuck Junior member Join Date: February 2, 2010 Posts: 6,846	300AAC/BO: Quite a bit of good accurate ammo at "reasonable" prices. Usually fairly accurate and functional. Range is limited unless you just enjoy aiming at the moon to hit your target beyond 100 yards. Effectiveness on game is questionable beyond 150 yards due to low velocities. I have 2(or maybe 3) AR uppers in this caliber and have shot both super and sub sonic ammo with and w/o suppressor. The cartridges feed through standard mags and the platform functions well if a carbine gas is used. 7.62x39: If your barrel likes Hornady V-max or SST bullets, you've got it made. Those aren't the cheapest but do perform well. Otherwise ammo is cheap and can be found everywhere but quality is ???. Effectiveness on game with Hornady SST is all you can expect from this velocity/bullet weight within 150 yards but declines significantly beyond that. The earlier bolt problems may have been addressed and the magazines I use work well. Function of the platform is good as long as bullet shape is fairly pointy w/o too much exposed lead at the point. I have 3 uppers in this caliber. You have to make a choice: 300BO with commonality of parts, better accuracy, slightly more expensive ammo choices or 7.62x39 with specific bolt/mag issues and a plethora of cheap but often lower quality ammo.

October 24, 2017, 07:43 AM	#12
jersurf101 Senior Member Join Date: January 27, 2013 Location: Eastern NC Posts: 553	I have a 5.56 ar that I but 8 years ago and a .223 axis. I wanted another A R and had bought an Aero precision lower last year. I went with 300 blackout and love it. It is a soft shooter and brass is relatively easy to convert or come by. Wally world sells 300 blk ammo. With the popularity if 6.5s projectiles are not that expensive. The rifle is a soft shooter and very reliable for me. I went with a cbc 16" upper and a pistol length gas system What it came down to for me is starting to standardize projectiles. With a 3006, .308, 300wsm and a 30-30 the 300 blk makes sense for me. I am currently shooting old military 150 fmj pulls over 2400. Love this rifle. Barely shoot the .556 anymore.

October 24, 2017, 08:04 PM	#14
jonnyc Senior Member Join Date: July 20, 2009 Location: PA Posts: 1,731	Built my first AR a few months ago, in 5.56, and I've been a very happy camper. Decided to build another lower and was going to take my time thinking and deciding on an upper. A week later I already had my 300BLK all together. Went to the range yesterday and whole-heartedly confirmed I made the right choice. __________________ 2024 PA Cartridge Collector Show; Aug. 16-17, 2024!!! Buy...Sell...Trade All Types of Ammunition & Ordnance PM or email me for 2024 show details.

October 24, 2017, 11:57 PM	#15
stagpanther Senior Member Join Date: March 2, 2014 Posts: 11,789	300 BLK is a good, easy build--but has it's limits. If 30 cal out of a common AR 15 set-up is a must you're probably going to need to look at wildcats, which are going to be expensive to feed if you're not a reloader. AR15 performance is a "top gun" with 6.8 spc and he also makes a 30 harret cat based on the 6.8 case which looks very interesting to me--though, like the 300 BLK your bullet choices are likely going to be limited, them's the breaks because you're selecting a caliber for an action which was not designed for the size/length of a 30 cal. __________________ "Everyone speaks gun."--Robert O'Neill *I am NOT an expert--I do not have any formal experience or certification in firearms use or testing; use any information I post at your own risk!* Last edited by stagpanther; October 25, 2017 at 12:04 AM.

October 25, 2017, 05:06 AM	#16
jetinteriorguy Senior Member Join Date: April 28, 2013 Posts: 3,176	I bought an AR Stoner upper in 7.62x39 last year and put it on an AeroPrecision lower that I put together and it's one of my favorite rifles. With a crappy red dot it's sub 2MOA at 100 yds, I'm going to scope it and see if I can get closer to MOA. Just get the AR Stoner mags, or the ASC mags and your good. You can also use standard .223 mags as long as you limit them to 5 rounds. I can't attest to durability but I have put close to a thousand rounds down range with no issues. I also have a friend with the PSA version and his experience is pretty much the same as mine.

November 3, 2017, 08:47 PM	#18
15plus1 Member Join Date: March 5, 2017 Posts: 57	Thanks for all the input. It's still a bit to think about as I really don't have the funds to tinker much. I think I'm enamored with the x39 in an AR because it's a little weird and not supposed to be. Ammunition availability does play a big part though. I'm not discounting the .308 Ar-10, however ammo cost plays a big part there and I have no plans to reload at this time. I've tried the AK, and I'm not a big fan of the platform due to a few factors, but I do like the way the caliber performs as I am looking for a short range/decent power option. Thanks to all for input and to those who were able to recommend some good parts to look into.