Home Forums Hunting & Shooting Hunter's Campfire 270AR SPR (New AR-15 cartridge coming this fall)

Sadly, right now all brass has an availability problem, but as for the inconsistency in .243 WSSM brass, it ain't so. Some criticized the fact that it has thick necks that are inconsistent, yet in loading around 1K of my brass horde I found neck thickness to average .0007" with the max being .0015" by measurement. I tried neck turning and annealing but gave up as it produced no discernible advantage. Winchester's brass is about as good as it gets for any brass - including overrated Lapua - right out of the bag.

Back in 1964-65 the AR-15/M-16 was chosen over the AR-10 to allow a larger quantity of lighter ammunition to be carried into battle. I recall reading one critique where the bullets were found sticking in the pad of built up paper targets at 200 meters on military ranges. Yet I have seen it dispatch young feral pigs with a premium hunting bullet at ranges no greater than 150 yards - tasty. Of course you are reading comments from a guy that just built a custom bolt action upper with no gas system in .204 Ruger with a 24" Hart 1:9' twist barrel. The barrel has no gas port. So take everything I say with the appropriate grain of salt, because I'm a varmint hunter so deer get a free pass.

Now there's something I do know a little about. Loaded up some Barns .257" 80 grain TTSX bullets in my .257 Roberts Ackley custom Remington 700, because of California's lead free zone. I expected they would punch a hole clear through a ground squirrel, but just the hydrostatic shock should do the job. My load drove these little bullets at 3,578 fps over the Oehler 35P. Here's the first hit at fairly close range about 50 yards:



More followed at between 150 and 200 yards, here's three in row:



The one pointed to in the photo above was about the smallest squirrel I ever hit at that range, his body was no longer than 4", not much resistence but a good splat anyway:



Good little bullet. Here's a 10 shot 100 yard group that shows I'm good for 8 out of 10 shots. That diamond is .5" on a side:



Wrote a note to Barnes and they said looks like the TTSX was opening earlier than they believed. If you can get it out of the muzzle at something around 3,200 fps it ought to do deer quite well, but they always shoot through after messing up a lot of tissue.

John, thanks for the first hand photographic evidence.
Nice prarie paintjob.

The 7mm IHMSA? A shortened & necked .300 Savage? I was just thinking about that...

PH, great job showing your ignorance.
The 7mm IMHSA been around the competition circuts for about 30 years.

When introduced to something new, a respectful question will go alot further then a patranizing bunny pic.

A five-pound scoped upper that I can swap out in less than a minute on the AR shorty I'm holding that gives me 600yd "dick in the dirt//DRT" capability sounds like quite an incentive to me, but that's just me. A "Jovian thunderbolt" that'll fit in a racqetball case.

Hey, show some goddam respect.

The guy knows how to press a START button, and snap lego together.

GTC

You guys got no sense of humor. Wow wound up like a bunch of angry liberals.

Just a little explanation about this. SoCal kind of jumped the gun on this thing. He was new to 68forums got excited when he saw this but he didn't know how I do things. First off this 270AR is a wildcat, it will never be submitted to SAAMI and no factory will ever load ammo for it. It will never be advertised and it's only avail as a special project offer to 68forums members just like the 6 and 6.5 BRX's were. 55 barrels were made and are being Melonite treated now.
The object was to be able to use 130gr 277 bullets in an AR15 at a decent velocity for hunting. The 6.8 can't push 130s fast enough to get reliable expansion at longer hunting ranges 3-400yds. Some are using 130 and 140 Bergers in their 6.8 but only pushing them to 24-2500fps. One 130 Berger has a BC of .496, it will not work in the 6.8 because part of the ogive is back in the case mouth even when loaded to 2.3". The 270AR case is a little shorter than the 6.8 case so bullets with longer ogives can be used. When 6.5Creedmoor brass is used the capacity is 45.4 gr, Lapua 6.5x47 brass apx 44.7gr. The 30 Remington AR has a cap of 44gr. The problem with the RAR is it has a .492 rim not the standard .473 and it took Remington 3 years to get brass to the market.
[img:center]http://68forums.com/forums/attachment.php?attachmentid=10250&d=1380677266[/img]
The BRXs when using Lapua brass has a cap of 42gr, I knew I could get a little more vel by using a longer case and still use 130gr bullets and no fireforming is needed like on the BRXs. The 6.5 BRX will push 123gr bullets to 2750-2800max out of a 20" barrel. The 6 BRX will push 95gr SMKs to 3200fps out of the 22" Krieger. The 270AR will push 130 Bergers to 2800fps max with 36gr 8208 out of a 20" barrrel. That is the max load with that powder. I have not tested all powder in the range. CFE will not hit 2800 but others like N530 or N540 may. I always push to find the max first then back down in .5 gr increments until I find the accuracy I want, usually 1/2MOA. That way I end up with the fastest accurate load.
I designed the 800 series bolts in 2009 and have been shooting a 6BRX since. During testing I pushed it hard enough to turn the Lapua case into belted magnums. Well over 60k. The bolt still hasn't broken.
The .800 series bolts are .800 in dia where a AR15 bolt is .750. The lugs at the root are wider than a AR10 bolt and they are made from 9310 where AR10 bolts are 8620. During the destruction lab test in 2009 the Armalite AR10 bolt broke before the 800 series did. The bottom lugs are clearanced because they stick down further than a AR15 bolt. If there wasn't .025" taken off the tips they would catch the 30 degree shoulder on the cartridge in the mag. Where the root of the lug attaches to the body of the bolt is where the strength is not out on the tip. The reason it is mentioned is so anyone seeing the flat spot on those 2 lugs may understand why it is there.
277? The company that does the deep hole drilling is running 3 shifts around the clock drilling 5.56 and 6.8 barrels. They do not want to stop and retool to drill 6.5 or 308 barrels. I've been waiting over a year for 300 264LBC barrels. All manufactures are running at max capacity with most having 18 month waits. I have production spots in line and can get 5.56 and 6.8 barrels in 4 months. The 277 bullets have better BC than the 308 or 7mms until the 7mm gets up to 160gr which is too heavy for a case this size. Same with the 308s by the time you get to a decent BC they are too heavy. The 155s ogives are too long so the case would need to be very short reducing case capacity and velocity. All in all this .277 will work in a AR and give those that want to shoot 130s the vehicle to do it.
It will push a 120gr to apx the same velocity as a 25 WSSM factory load out of the same length barrel. The problem with a wssm in an AR15 is a special receiver, carrier, extension, barrel and bolt must be used and a .550 dia case in a .980 dia barrel makes a very thin chamber wall. A .215" thick wall around a cartridge making 65000psi.

Good advice!

I hunt in the woods, will it kill a deer at 100 yards which is 25 yards further then I've ever killed one of the 30 or so deer I've killed.

Mike

the old 270 Savage from the P.O. Ackley days...
nothing new here...

Yawn

This bears repeating. Only a mofo as dumb as locoweed could be silly enough to think that the number of deer a poster has killed (of unknown size) would be, in any way, applicable to the discussion on a new cartridges' ballistics. What a simpleton. Be advised montanans, this dumbass might build a YOUR house next.

You were pretty far in the bottle with that one.. Good job!

New here, aren't you...well have fun making new friends.


ps, and for what it is worth, cross' word is good.

Now YOU can stay, we could do with more posts from you.

FWIW an ogive inside the case neck is no big deal, UNLESS you can't get enough bullet and tension to hold it in place in the neck.

A bit OT but thought I"d toss that out there.

There are a few of us running 75 amax in 223 at 2.250 mag length... doesn't look right, but I"ve shot some snug groups, order of 1 inch give or take at 300 yards with such loaded...out of an AR.

What some of the curmudgeons are missing, is a round like this shouldn't be compared to your favorite bolt action round and dismissed as nothing new. It should be considered for the platform in which it is intended.

Kind of like comparing a 302 Ford to a 460, which wouldn't mean shyt if you're intending to slap it in a 4000lb truck. However, that 302 suddenly looks real good when the platform you're discussing is a 2800lb mustang, and the 460 won't fit without heavy modification and turning that nimble pony into a front heavy plow.

This 270AR is pushing the envelope of an unmodified AR-15. That is where it is of interest to those who are interested in getting everything out of an AR that they can. As Constructor said, it's just a wildcat, but wildcats are cool, especially when they are viewed within the constraints of the platform for which they are intended.

That they are, and free information from the fellow doing the work is always interesting.