Long chamber AR

[mmcnx2]

I've got my 223 AR done for some time and am thinking about a larger caliber in the AR platform. A few questions:

1. What caliber would you go with? I've been looking at the traditional 308 or something more wild like 6.5. Any other to consider and why?

2. What is the best source for parts, I've noticed there seems to be a few different platforms and parts are not interchangeable. Any pro's cons?

And yes I've read just about every post on AR15.com

[dsm2nr]

300 AAC Blackout is what I will be building when I move up calibers.

It really depends what your point of use will be for the gun.

[farmerj]

300 AAC Blackout is what I will be building when I move up calibers.

It really depends what your point of use will be for the gun.

same here or else the .300 or .338 whisper.

[Erud]

In my opinion, the Blackout is really only worthwhile if you can suppress it. Otherwise, it's just a slow and weak .30 caliber.

In a small frame AR, the 6.5 grendel is tough to beat for almost any application, from long-range target shooting, to hunting, etc. Mild recoil, excellent ballistics with all of the great 6.5 bullets out there and almost total interchangeability with standard AR parts, aside from mags, barrel and bolt. If you reload, the 6mm Turbo 40 Improved(6.5 Grendel necked down to 6mm and fire-formed to blow the shoulder to 40 degree) performs even better, but is a bit more work. I've shot about 3500 rounds of 6T40 in the last year and I am completely sold on it's capabilities. From 600 yards and in it's as good as anything and better than most and it holds it's own out to 1k if the wind isn't too bad. It is my go-to round for NRA Highpower competition.

If you're looking for a large frame, .308's are plentiful and can be had pretty reasonably. I've got a DPMS LR308 with a 24" upper that is a 3/4 MOA shooter and a 16" AP4 upper that will shoot about 1.5 MOA out to 600 yards with a 6x scope shooting off a backpack. IF you are looking for more performance out of the 308 sized platform, rifles can be had in .243 and .260, as well as other calibers.

If I were you, Id just buy this, from me:

viewtopic.php?f=49&t=25258

Though I admit, I'm a little biased....

Good luck!

[timwarner]

Companies make .416 and .50BMG single shot bolt action uppers for an ar-15 lower.
So why not a 308 or 300win mag, similiar bolt action single shot upper for a small frame lower?

[MnHornet]

My 450 kick butt. A buddy of mine has a 6.8 that is a sweet shooter.

[rukwikenuf]

so what's the argument between the 6.5 Grendel and the 6.8 SPC? i'd personally like to go with a 6.8 SPC when i have the money, but is it a better performer than the 6.5 Grendel? or is the Grendel better? why?

and BTW, those are serious questions, serious responses would be appreciated

[MnHornet]

I think it comes down to popularity and availability of ammo, or ammo components. Pretty sure my buddy uses Pmags for his 6.8, not sure if the 6.5 uses special mags or not. I don't think one has a "major" ballistic advantage over the other. This could easily turn into a ford chevy debate.

[Erud]

so what's the argument between the 6.5 Grendel and the 6.8 SPC? i'd personally like to go with a 6.8 SPC when i have the money, but is it a better performer than the 6.5 Grendel? or is the Grendel better? why?

and BTW, those are serious questions, serious responses would be appreciated

It's an argument that has gone on since the beginning of time. They are similar in a lot of ways and it does come down to personal preference for most. Either will require a different bolt and mags, though standard .223/5.56 mags can be modified to work with either. Either is a step up from .223 in stopping power and ballistics. Factory ammo is available for both, but is fairly expensive and can be hard to find. Either cartridge will be most effective if you load your own(as with most any cartridge...).

The 6.8 was designed to be a harder-hitting alternative to the 5.56 out of a 16-20" barrel yet still fit in an AR-sized platform. It does that.

The Grendel has the advantage of better bullet selection in 6.5 caliber over 6.8. There are some great, high-BC choices in the 120-ish grain neighborhood, like the 123 SMK and 123 Lapua Scenar that will beat any of the 6.8 bullets available. The differences get more noticeable out past 400 yards or so. The short case length of the Grendel allow long bullets to be seated long and still fit in a standard 223-sized mag. The Grendel also uses Lapua brass, which is a big advantage if you are a reloader.

I am not looking to get into a big argument with anyone over the merits of either, the info is all out there to make your own decision. I prefer the Grendel for the above reasons.

Good luck,
Erik

[JJ]

Personally I am leaning strongly towards a 6x45 because I can still use standard mags for my next build.

That said it would all depend on price for me. 6.8SPC would be fun, but the mags are outrageous. The Blackout/300/221/fireball is cool as well, but without a can it seems like a worthless investment. 6mmAR 40deg Improved has some promise, as does it's parent case 6.5Grendel. http://www.6mmbr.com/gunweek068.html

[Erud]

Personally I am leaning strongly towards a 6x45 because I can still use standard mags for my next build.

That said it would all depend on price for me. 6.8SPC would be fun, but the mags are outrageous. The Blackout/300/221/fireball is cool as well, but without a can it seems like a worthless investment. 6mmAR 40deg Improved has some promise, as does it's parent case 6.5Grendel. http://www.6mmbr.com/gunweek068.html

The 6x45 does not compare well to the 6T40, aside from the mags and cheap brass. It holds about 5 grains less powder and the case is too long to use the heavier 6mm bullets without seating them way below the donut, thus reducing charge capacity even more. With the light 6mm bullets, you really are not getting the benefits of 6mm ballistics and will be limited similarly to a standard .223. That's giving up a lot, just to be able to use the mags you already have.....

[JJ]

The 6x45 does not compare well to the 6T40, aside from the mags and cheap brass. It holds about 5 grains less powder and the case is too long to use the heavier 6mm bullets without seating them way below the donut, thus reducing charge capacity even more. With the light 6mm bullets, you really are not getting the benefits of 6mm ballistics and will be limited similarly to a standard .223. That's giving up a lot, just to be able to use the mags you already have.....

Not telling me anything I don't know. But my next "build" is taking my 5.56 pistol to something else. Not really sure I want to spend a ton on brass, dies, new bolt, and such on something that may not work, and 6x45 won't cost me chit.

But if money wasn't an issue, i might eff with any of the above just because I could.

[Erud]

The 6x45 does not compare well to the 6T40, aside from the mags and cheap brass. It holds about 5 grains less powder and the case is too long to use the heavier 6mm bullets without seating them way below the donut, thus reducing charge capacity even more. With the light 6mm bullets, you really are not getting the benefits of 6mm ballistics and will be limited similarly to a standard .223. That's giving up a lot, just to be able to use the mags you already have.....

Not telling me anything I don't know. But my next "build" is taking my 5.56 pistol to something else. Not really sure I want to spend a ton on brass, dies, new bolt, and such on something that may not work, and 6x45 won't cost me chit.

But if money wasn't an issue, i might eff with any of the above just because I could.

Then you are golden.

Good luck,
Erik

[rsilvers]

In my opinion, the Blackout is really only worthwhile if you can suppress it. Otherwise, it's just a slow and weak .30 caliber.

Just because it suppresses well does not mean it is any less useful unsuppressed than anything else. It is more powerful than 5.56mm. From a 9 inch barrel, 300 BLK matches an M4 for muzzle energy.

At 300 meters, Remington 125 grain Match 300 BLK ammo is 16.7% more energy than even the hot Lapua 7.62x39mm ammo which is $62 per box at Midway.

300 BLK is simply the most powerful 30 cal cartridge that can be shot from an AR15 using normal magazines with full 30 round capacity.

It has caught on, and over 75 companies have announced products for it and that seems to be growing weekly.

http://www.youtube.com/watch?v=hRw-ypBgrKo

And the ammo is way cheaper than 6.5 or 6.8, and only 10-25 cents a case if you reload (depending on who you get it from) - 1/5 to 1/2 the price of 6.8 brass.

http://www.midwayusa.com/product/547535 ... -box-of-20

[mmcnx2]

Guys maybe I should add I'm looking to something tht can reach out and touch in the +500yd range. So talk of a 9 inch barrel make me wonder why I just would not use my 45 1911 and be done with it. So with teh rnage requirement what are the thoughts on calibers?