270ar

[Fenderbuilt27]

270 AR
Available in limited quantities for the AR15, a .277 caliber cartridge capable of propelling 120 gr bullets over 2900fps and 130gr 270 bullets to 2800fps out of AR15 20" barrels. It is apx 200 fps faster than the 6.8 making it a full power hunting cartridge usable in the AR15. It is based on a shortened 6.5x47 Lapua or Hornady 6.5 Creedmoor case.
These are available through AR15 Performance (ARP). You'll have to build your on rifle because they only sale the barrels but it sounds pretty interesting.

 

[Fenderbuilt27]

All of these special projects are just that, special projects that I think some may be interested in and to keep me from becoming bored from doing the same ol thing every day. I have no misconceptions that any of these may become mainstream. Our money makers are the 5.56 and 6.8 and they have priority over all other production. I'm sorry it takes so long to produce these special projects but I must keep the money flowing in order to produce the parts.
The 270AR is a hunting cartridge, mainly designed to get an AR15 shooting the wide 130gr range of .277 bullets. 270 bullets are some of the best considering the balance of weight and BC. It is apx 200fps faster than a 30-30 and 100-150fps slower than a 308 using 130gr bullets. It has apx the same performance as the 25WSSM when shooting 120gr bullets from the same length barrel(2900fps out of a 20"). This cartridge has a little more case capacity than the 30 Rem AR ( 45.4 Creedmoor case VS 44.gr RAR)and has a better weight range of bullets with better BCs for a case this size...the .277s.
The case can be made from plenty of existing brass(Creedmoor preferred choice), no need to wait 3 years for Remington to produce 30RAR brass again. Hornady 6.5 Creedmoor, Win 308-243 or Black Hills 308 brass will work without turning the necks. LC military brass, Federal and R-P is too thick, the necks will need to be turned apx .004" but that just helps the concentricity. Lapua brass can be used but the lower half of the neck needs to be turned to be uniform. The 270AR will feed from PRI 6.8 mags.
To make a conversion you will need a barrel which includes our 800 series barrel extension, an 800 series bolt with a .473 dia face, PRI 6.8 mags and modified 6.5x47 bushing type reloading dies. The 6.5x47 dies need to have .125" cut from the bottom of the resize die. There is no need to hog out a receiver, any standard flat top A3(not DPMS lo-pro)receiver has an ejection port large enough to work. Standard AR15 or M16 carriers will work with the 800 series bolts.

This 270 AR is available for 68forum members only, most people have no business with a wildcat and I don't need the trouble.

At this point I am pretty sure every bullet can be loaded out to 2.3" without being stuffed into the lands.

Gas ports --On these 20" barrels I'm porting them with a .086 to start. I suggest working up the load to find the accuracy and velocity you want and plan to use then if it does not cycle drill the port out with a 3/32" bit.

Compared to the Grendel shooting a 123gr SMK or AMAX at 2550 from a 20" barrel, the 270AR shooting a 130 Berger will have 12" less drop and 3" less drift at 600 yds when both are zeroed at 300yds as well as going over 100fps faster. The 130 is still traveling almost 1800fps at 600 yds.
130gr G1 BC bullet of.496---run that through a ballistics program- http://buybergerbullets.3dcartstores.com/270-Cal-130-Grain-Classic-Hunter_p_175.html



5.56, 264LBC,270AR,6.5x47,308

Click image for larger version. Name: 270AR.jpg Views: 402 Size: 3.1 KB ID: 9947
The 270ARs shoulder is only .015 lower than the 6.8, the mouth .040 lower. It's very close to the length of the 6.8 but .473 dia instead of .422. 44gr VS 36gr in the 6.8. With some bullets it may be 200fps faster than the 6.8. Everyone talks about catting the 30RAR, this photo shows just how big this 270AR(right) is when compared to the Remington AR.
Click image for larger version. Name: rar_vs_270.jpg Views: 261 Size: 101.3 KB ID: 10250

I know there will be a bunch of guys with a 6.5 fetish yakking "why not a 6.5". If I shorten the case enough to use the long 6.5 bullets it's back to the length of a 6.5BRX. The 6.5 BRX has almost the same case capacity as a 30RAR necked down to 6.5 and the BR brass is much easier to find. The BC doesn't kill animals. This is about making the best AR15 cartridge for hunting not punching paper.


Dies- 6.5x47 bushing dies must be used. 6.5x47 dies must be shortened .125". The hole below the bushing needs to be opened to .302"(7.7mm from Mcmaster -Carr). The seater die stem needs to be screwed down to seat the bullet before the die crimps the neck. A .298-.300 bushing should work with Lapua, Hornady and Black Hills. A .302 may work better with Win Brass.
SIZING/forming- Use only imperial size wax on the case and very small amounts.
Use the 6.5x47 die without the bushing or stem in it. Trim the brass to 1.646" after this step, chamfer the outside of the mouth after trimming. Finish with the 6.5x47 die with the correct bushing. Use a small amount of case lube in the neck area to prevent dents and if you get dents clean the dies out to remove the excess before continuing.
Seating- I use a 7mm08 seating die.
One users comments-
"I had myself all worked up for no reason. Been away for past week and have just now been able to try re-forming some 308 cases. Using Imperial die wax and only the RCBS modified die, my first case popped out of mt Forster Co-ax press as pretty as can be. Second case had a little crease in the shoulder. For my 3rd-13th practice case, I pulled out the long handle for the press for extra leverage, took my time, making 3-5 passes until ram completely bottomed out. Most of them came out just fine. Toward the end of my practice run, I found that I had best results using a method described above by another person. Pull handle until resistance is met, I then lower case from die, wipe excess wax and go again, rotating case along the way.

It seems that the least amount of wax, the better. And wipe off the excess from the case as you're working it in."


Case- You will have to shorten the Creedmoor brass to 1.646" after the second step, the wall in the chamber is 1.656".
The neck in the chamber is .311" dia. It is possible to use 308 brass if the loaded neck is .307" or you turn the necks to .307-.308.
There is plenty of room in the chamber so neck turning is not needed with Lapua, Creedmoor or Win brass. When forming the first time I suggest running a NTA27 or e 27 expander mandrel into the necks before seating the bullets. The Expander die ( http://www.sinclairintl.com/reloadin...prod38807.aspx )and NTA27 ( http://www.sinclairintl.com/reloadin...0(xzzx277) )mandrel is available from Sinclair. If you do not do this you take a risk of the inside diameter of the neck being too small. If it is too small the seater cup may deform the bullet because it takes too much pressure to expand the neck back out to bullet dia.
I'll provide links to every thing needed here in this 1st post.


Powders that show the most promise- I am working up to the max loads, as long as you stay under these loads they should be safe.
Start 1.5-2gr below any load listed here and work up to find an accurate load.
The loads shown are near max with 130gr Bergers.
CFE 223 is on the slow side with 130gr bullets.
8208--36gr pushed 130 Berger to 2796fps
N530--35gr 2801fps
H335--37.5gr=2889fps
1200R-34=2789

I developed my first cat in 82. If the cartridge hasn't been made before there is no book to look up the load data. The way I do it is I try every powder in the range with each bullet and run them up to the max charge so I know what max is. When I see cratered primers or primers starting to flatten(assuming the brass was sized .002-.004 shorter than the chamber) I know I'm near max. At that point I know I can load charges in .5gr increments going backwards from max until I find a load that meets my accuracy goals. That way I get maximum velocity and the accuracy instead of playing around 100 or 200fps slower than what I could get because I don't know where max is.

NOTICE---These are near max loads for the reason above. Be careful when using formed 308 brass start with a load at least 3 gr lower and workup. Accuracy will most likely be found 1/2gr -1gr below the max loads.

85 and 90gr bullets---RE7 36gr produced 3290fps

7/31/13- all loaded to OAL 2.29" 45gr gross case capacity(Creedmoor brass), 18" barrel.
36gr 8208- Hornady 120gr SST produced 2820fps.
37gr IMR 8208- 100gr nosler accubond=2994fps
36gr Alliant 1200R - 105 GS SP solid copper=2996fps
37gr Alliant Re7- 85gr TSX=3450fps

10/18/13-Using Creedmoor brass CCI BR4 primers, 20" barrel. The lands in this chamber are a little closer (.025) than the 6.8s so the same COAL can be used. IMO there is plenty of velocity here with the 130gr bullets.
130gr Berger-36gr 8208=2796fps
120gr SSt-37gr 8208=2887
110gr HPBT-38gr 8208=2998-

12/8/13-20" barrel
110gr Hornady HPBT-near max loads
35gr 10X=2992--10X started cratering primers before N530 or 8208 IMO 10x should be used on bullets 85-110gr
35gr N530=3002
35gr H4895=2748

85gr TSX-near max loads
38gr AA2200=3375
38gr 1200R=3448

99gr GS Custom HV
37gr 1200R=3180

For the guys following this Bruno's shooters supply has some powder in stock. please keep it quite if you want powder.
After todays testing with the 6.8 and 1200R powder I will retest every bullet weight with 1200R.

12/15/13
Using Hornady Creedmoor brass

34gr of 1200R behind the 130 is max IMO...2789fps.

37gr H335, 130 berger=2850
37.5gr H335, 130 berger=2889--close to max, no cratering, primer starting to flatten out a little.

38gr H335, 120gr SST=2977
35gr 1200R, 120 SST=2952
38gr H335, 110gr HPBT=3045
35gr 1200R,110gr HPBT=3023

12/19/13-- As of now only 5 of these have been shipped out and all were to members of this forum.
We're trying to get custom dies made but the holidays are here and everyone is in slow motion. When I get it all straightened out more will be avail.

1/1/14-After testing the 270AR and BRX cartridges in the SIX8 Magpul Pmags, they will not work. The follower will not hold the tips up.

 

[HandgunHTR]

Is this a copy and paste, or are you affiliated with ARP?

Oh, and the statement " It is apx 200 fps faster than the 6.8 making it a full power hunting cartridge usable in the AR15.", is just stupid.

The 6.8 is a full power hunting cartridge usable in the AR15 in and of itself. No need for a "fuller" power one.

 

[Fenderbuilt27]

Is this a copy and paste, or are you affiliated with ARP?

Oh, and the statement " It is apx 200 fps faster than the 6.8 making it a full power hunting cartridge usable in the AR15.", is just stupid.

The 6.8 is a full power hunting cartridge usable in the AR15 in and of itself. No need for a "fuller" power one.

I am in no way affiliated with ARP. I'm in the process of building a 6.8 SPC. I went to another forum to get some ideas and saw this wildcat. I thought it was pretty interesting so I copied and pasted the info from the other forum on this forum. Is there something I've done wrong?

 

[leoparddog]

Is there something I've done wrong?

No, it just reads like an advertisement or a promotion.

 

[Fenderbuilt27]

No, it just reads like an advertisement or a promotion.

I think that it was but it was all the information on the round. I just posted it for information.

 

[HandgunHTR]

I am in no way affiliated with ARP. I'm in the process of building a 6.8 SPC. I went to another forum to get some ideas and saw this wildcat. I thought it was pretty interesting so I copied and pasted the info from the other forum on this forum. Is there something I've done wrong?

No, it just reads like an advertisement or a promotion.

Yep, that's why I asked.

You will love the 6.8. I have one and I see no practical reason to build a 270AR instead of a 6.8.

 

[NCummins]

I'll bet you could hop a 6.8spc to those velocities without a problem.

 

[Ezbagr]

The guy that came up with this wilcat is Harrison Beene-I think that is how you spell his last name-"H" as they call him was one of the ones that help push the 6.8 SPC to where it is at today-without him I do not know where the 6.8 would be today.
As far as pushing the 6.8 to the velocities of the 270AR-I do not think that that is possible.
H is also working on another wildcat-no name yet-where I Believe that they are going to take some of the 6.5 Grendel bullets and put them in a 6.8 case.
This guy knows what he is doing.
Another interesting wildcat is the .277 Wolverine-Mark at Mad Dog Weapons Systems {MDWS} is taking the lighter weight 6.8 bullets and putting them in 5.56 cases. This widcat is still in the infancy stages but it is going to happen.
If you all need some reading to pass the time you should jump over to the 68forums-there is alot of good reading over there.

 

[GunnSmokeer]

.243 or 7mm-8

If I wanted a medium-bore long-range hunting caliber for an AR platform rifle, why wouldn't I go with a .308 or any of the factory-standard loads that are necked-down variations of that .308 case?
Like the 7mm-08 Rem and the .243 Win?

Aren't both of them fast and flat-shooting rounds, using bullets of 100 or 120 grains, with velocity near 3000 f.p.s.?

And they're not wildcats.
Last I checked, there were dozens of models of AR rifle chambered in these calibers.

___________________________________________

OR is the big difference --between those rounds and the 6.8 or the 270AR ---that those .308-based rounds have to be fired from a different sized upper AND LOWER, whereas the smaller cartridges can just be an upper-and-magazine only change that uses the same AR lower that you normally shoot .223 thru?

 

[Ezbagr]

If I wanted a medium-bore long-range hunting caliber for an AR platform rifle, why wouldn't I go with a .308 or any of the factory-standard loads that are necked-down variations of that .308 case?
Like the 7mm-08 Rem and the .243 Win?

Aren't both of them fast and flat-shooting rounds, using bullets of 100 or 120 grains, with velocity near 3000 f.p.s.?

And they're not wildcats.
Last I checked, there were dozens of models of AR rifle chambered in these calibers.

___________________________________________

OR is the big difference --between those rounds and the 6.8 or the 270AR ---that those .308-based rounds have to be fired from a different sized upper AND LOWER, whereas the smaller cartridges can just be an upper-and-magazine only change that uses the same AR lower that you normally shoot .223 thru?

Gunnsmokeer, I am not really do not know much about the .308 but I do kmow that these wildcats are only an upper-barrel and magazine change. I do believe that the 270AR was brought about so that you could shoot some of the midweight .270 bullets. As far as the Wolverine .277, I think that the 2 advantages of this one is the easy to find and less costly 5.56 brass and being able to shoot heavier bullets with that brass.

 

[Wiskey_33]

The 6.8 isn't a full power hunting cartridge?

I guess the deer I've taken with mine can get out of my freezer then as they're not really dead.

The 6.8 is perfectly suitable for taking game. I've read articles at 68forums where Elk have been taken with a 6.8, black bear too.

 

[leoparddog]

For some reason the 6.8 doesn't trip my trigger. The 6.5mm rounds do for some reason. I guess its because I used to have a 260 Rem. I'd be interested in a 6.5mm round that would allow me to use my AR15 lower. The Grendel may let me do that but they are just too expensive still.

 

[Fenderbuilt27]

I'm looking to build me a 6.8 for next deer season. It seems from the 6.8 forums website that ARP is a pretty respected company.

 

[HandgunHTR]

ARP is a VERY respected company.

GunnSmokeer - the reason for the 6.8SPC and the the other wildcats is that they are AR-15 platform. The .308 is AR-10 platform. While they look similar, they are pretty different in terms of weight. The AR-10 is quite a bit beefier.
So, with the 6.8, all you have to do is swap out the upper and magazine and you have a bone fide big game rifle.

 

[Ezbagr]

This .270AR will keep up with the 6.5 Grendel and possibly even outdo it at the longer range that the 6.5 outruns the 6.8.
Saying that, it is a wildcat and unless you are really into working with wildcats it may not be worth it for alot of people.
I do know that "H" has 5 barrels out and being tested. I also know that he has placed an order for fifty of these barrels and he is also working on getting the correct dies made.

 

[mike bell]

My first AR build was a .300 whisper. Now commonly known as the .300 AAC Blackout. The super sonic loads for the 110-125gr bullets are between 2000-2400fps. Basicly, its a .223 case shortend and stuff with a .308 bullet.

It fits in standard AR and uses same mags, just have to swap the barrel..

 

[Big7]

The 6.8 isn't a full power hunting cartridge?

I guess the deer I've taken with mine can get out of my freezer then as they're not really dead.

The 6.8 is perfectly suitable for taking game. I've read articles at 68forums where Elk have been taken with a 6.8, black bear too.

Be pretty stupid to "hunt" Elk with a 6.8.

Most guides won't take you with anything less than an
'06. They really don't like that either but bare minimum.

What was it? In a hog pen?

Yeah.. I know, a .22 LR CAN kill just about anything.
Some things are just foolish though.

 

[GaSwamper1]

In regards to the .270AR trust me if ARP works on it it's probly gonna be a good performer. I've read a lot written by and about Harrison and the man is pretty good at what he does and has done great things for the 6.8 he was my choice for one of my 6.8 barrels and its fantastic the other was Wilson Combat which puts him in some legendary company IMO. As much as I like the 6.8 to me its not really a full power round yea plenty enough for deer and hog and can be made for smaller frame shooters to shoot slick as glass but not quite there. The MDWS .277 Wolverine project has been very interesting to follow and as someone looking to build an ar pistol and add to my reloading knowledge with a taste of wild catting I think Im going to give it a try. Not to take anything away from the blackout cause I almost went that route but I just couldn't get all in with the ballistics and many of the .308 rounds aren't made to expand at some of its velocities I think. And this coming from a guy that's always loved a 30.06.

 

[Nannyman]

Just love my 6.8. Build was easy and very accurate. Barrel and bolt from ARP. Other parts from different folks. Barnes made a specific .277 projectile for the 6.8. The 95gr TTSX expands at 1600fps just for the lower velocities of the 6.8. I am pushing mine a 2850fps muzzle velocity.
Just pull 2 pins and off comes .223 upper and on goes 6.8 upper.
Hard to beat.

JD