Tired of 556 ARs, what caliber for a DMR

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adcoch1

adcoch1

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I want to build a long range AR with some hitting power but I don't want to deviate from a standard ar-15 lower. If it were you and you wanted a reasonably priced build for hard hitting long range what would you pick? I don't want to build an AR-10 but I am not opposed to hand loading some super short magnum that single stacks in a mag either. Just need opinions, so fire away! Btw I like 30 Cal projectiles but this might need to be a departure from that. I also may hunt deer with it but that is my last consideration, mostly want accuracy and dependability and flexibility in differing weather conditions.
 
.25-45 Sharps and .277 Wolverine are both supposed to use everything but the barrel on a 5.56 AR if you are looking to maintain parts compatibility. I have no personal experience with either caliber though.
 
The AR-15 and "hard hitting long range" are antithetical. It can do loopy, low energy long range but that's it. None of the long range wildcats really do much for me, but 6.5-6.8 SPC (not a typo) is IMO about the right idea.
 
WhoMe? said:
I had very similar criteria and built a 6.5 Grendel. It met the need and I have been very happy with it.
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This has been my kind of idea too, anyone have any crono data for a pet load for the grendal out of an AR for ideas for load recipes? Also any other wildcats that use the same or similar rim diameter as 556? I forgot to mention that was one of my desires also, to keep costs down. I would love to find something I missed over the years of reading about builds that could give 243 to 7mm-08 type performance in an AR platform. I have heard great things about the 6.8 hybrids and the Grendel, just wanted to try for some hard data and opinions before I start barrel shopping...
 
Hard hitting long range isn't what intermediate cartridges are designed to do. At a minimum the .308 was once used for that. The military moved to .338 Magnum for that application now, if and when .50 BMG isn't available.

Stretches the perspective, doesn't it? We need to know what the OP considers "long range" and just how hard it needs to hit. THEN we can make recommendations about which cartridge - and knowing that, whether or not it will even load into the restricted magazine length of the AR15 at all. There's a limit to that, about 2.300" and why so many different alternate cartridges have been designed to take advantage of case and bullet diameter.

But case length has a finite limit when you try to put a bullet on the top of it and keep it under 2.300." Simple math.

If, by long range, it's meant to still carry about 1,000 foot pounds, how far out is it needed? 1,000 foot pounds is a somewhat arbitrary figure but was calculated some time back as an ethical floor on the necessary force to down game reliably. Not a guarantee - because shot placement is MORE important, but at least it delivers enough that a marginal shot can dispatch the game.

OP, how far out do you need 1,000 foot pounds of force? That determines bullet mass, and therefore, diameter. It also determines case capacity of powder, and that determines a window of case diameter and length. With the bullet on top, you get a relative idea of the maximum overall loaded length.

In a vague determination, "long range hard hitting" isn't going to happen with AR15's. The military abandoned the guns that did that because they weren't suited for the realities of combat. To shoot those larger cartridges, noted as being the better choice for long range and extended power, it's going to take an AR10 with .308 as one example of a minimum power requirement. None of the typical AR15 alternates with a maximum 2.300" length can do it - regardless of the claims of some fan boys.

And a few will trot out reams of ballistics to make their point. I only have to read where the limit of ethical force stops to understand their effective range, not their theoretical fantasy application. And a "major power" cartridge will do better every time.

We can do a lot with a 3 1/2" pocket knife, but it won't do what a 6" fixed blade can do. It's about size, mass, and how much applied power it can exercise. And those 6" knives can't do what a tomahawk does better.

Define "long range" and "hard hitting" or the thread will simply deteriorate into a series of "Mine's best!" chest thumping.
 
But case length has a finite limit when you try to put a bullet on the top of it and keep it under 2.300." Simple math.
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The exception is going bigger diameter to fill the mag side to side. .458 SOCOM does this, but bullets are heavy and have a large cross section

I hunt with an AR .358 WSSM. It also fills the mag but has better ballistics. Just took a 200#+ buck last weekend. Have taken deer to 279 yards. Dunno if that is long range for you but it is in Indiana. Holds 49 grains with a 200 grain bullet. If you would neck that case to 6.5 I would think it should crank pretty well. Dunno how it compare to the Grendel

Upper was $950 plus dies. You could get uppers in standard WSSM calibers in the past. Runs normal AR lower

I'd be inclined to go with the Grendel since it is factory standard

Edit to add.....the Grendel only uses +/- 28 grains where the WSSM takes about 50
 
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I appreciate the input and I should have clarified hard hitting. I would like to get accuracy out to around 1000 yds with "hard hitting" power within 400. The mag length is the real problem and I think a 6-6.5mm bullet is really the only realistic diameter that can carry the weight to knock stuff down and still fly fast enough far enough to be accurate at range. Not looking for a 308,already have that in a decent platform, just want a precision rifle with as much reasonable energy as I can fit in a reliable AR-15.
 
I just recently sold my Remington 700 SPS Tactical in .308 and sold all of my. 308 ammo. I have two AR's both in 6.8spcII and two SLR-95's. I am completely sold on the 6.8spcII and am heavily invested in it.

For me bolt actions, although accurate, are clumsy and awkward to operate, load and unload, .308 semi-auto rifles are larger and heavier. Sure you have more energy at 500 yards, but in reality, I have no need or desire to shoot at 500 yards. I wouldn't take a shot on a game animal at 500 yards, I just don't feel comfortable doing it.

Keeping my shots around 300 yards, no animal will survive a good hit with the 6.8spcII.
So my thinking is that I have a "carbine" in a substantial caliber that I can hunt with, defend with and target shoot with. It is light, short, handy, accurate, reliable, uses hi-cap mags and it's semi-auto.

What makes the 6.8spcII so appealing as well is that it was designed to get maximum performance from shorter barrels, where other suggested cartridges need more barrel length to get their numbers, your not gaining much with more barrel length in the 6.8spcII.

I'm sure you've heard all this before, but terminal effects were one of the priorities when choosing the caliber to use in designing the 6.8spc and the .270 caliber offered the best terminal performance.

The cost and availability always comes up when other calibers are suggested for the AR, but any non-5.56 caliber is going to be more expensive than 5.56. I can find plenty of 6.8spc for $.70 a round now, but it's not prohibitive considering what I'm getting in an overall package.

For me it was hard to ignore the utter versatility of the 6.8spcII in the AR platform. It just makes too much sense for me.

Sticking with a standard AR lower, we are really limited in range and energy options considering what can fit into it's magazine well.

I'll just throw this pic up for my own personal gratification :)
20151117_163017_zpstqtuu9s0.jpg
 
6.5 Grendel load data I use

I built my 6.5 Grendel upper in June of 2014 and did work ups in several powders and bullets, I finally found the ultimate load for my upper. I need to say my upper has a 24 inch barrel with the 5R rifling, the barrel is a mid weight version in an attempt to keep the weight down. I tried free floating the barrel and never did hit the accuracy marks I desired so I went back to the standard hand guards and a Yankee Hill Machine gas block. I am guessing the 24 inch mid weight barrel being free floated allowed the harmonics to rob this set up`s accuracy, again this is my guess.

The most accurate load I found is using 123 grain Hornady SST bullets and Ramshot TAC powder 28.2 grains with overall length of 2.250. The average over the chronograph was 2502fps and produced 1/2 inch groups at 100 yards shooting from the bench. DISCLAIMER: this load may not work in your rifle and I strongly suggest you use a starting load lower than the load data listed above and work up in a safe manner to avoid any damage or injury to yourself and others nearby. 28.2 grains of Tac is the maximum load indicated in the Accurate Load Data listed for 6.5 Grendel, also the OAL is .010 shorter than listed on the Load Data information by Accurate. In my work up the 2.260 OAL did not result in the accuracy I got by shortening the OAL by .010. Be safe and good luck with your search for the desired caliber.
 
crazysccrmd said:
7mm Valkyrie AR will get you to almost 7mm-08 performance in a standard AR15. It's a neat wildcat based on the 6.5x47 Lapua.

http://www.7mmvalkyrie.com

3442547_orig.jpg
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Wow this is cool. And this is why I started this thread. I know quite a bit but I have learned a ton from reading up on other peoples opinions. Thanks THR! So 7mm Valkyrie or 6.5 Grendel..... hmmm what to do...
 
The Valkerie looks good, but compare similar barrel lengths to get true similar performance. I didnt look closely at the info on the web page to see what the barrel lengths were in the comparisons. Comparing a 24" Valkerie to a 16 or 18" 6.8 or whatever isnt really a direct comparison.

When comparing 6.5 Grendel to 6.8 spc, you also have to account for actual barrel lengths to get true comparisons of performance. Either would probably work for hunting medium game, the Grendel more likely for longer range shooting.

ETA: just looked at some info, the Valkerie looks like a strong contender for a useful round in the standard size AR. The 6.5 Grendel has Wolf ammo available for very reasonable prices for practice and plinking ammo. Adds some definite utility to the round, affordable shooting without having to reload.
 
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If I copied the right thing that should be a small spreadsheet showing velocities from the same loads and different barrel lengths.

2887096_orig.jpg
 
That 7mm Valkyrie looks pretty stout. From their charts it looks like you could hit 2,700 with 140's from a 20 in barrel. Pricey to get into though, $435 for a barrel and bolt, $140 for basic dies, $1.50 per case for brass. I guess if you want something high performance/low production like that you need to be willing to pay. If I were the OP I would probably skip all that and go with a 6.5 Grendel or 6.8 SPC, both are a step up from 5.56, while being fairly ubiquitous. If you want to veer away from the common rounds, you might as well go with some really high performance options like all of the WSSM's and WSSM derivatives (6.5 WSSM, .300 OSSM, .358 WSSM) offered by Dtech uppers.
 
My .358 WSSM upper came from D-Tech. Shilen barrel, obviously hand loads. When I got mine lead time was about a year.

After using mine my hunting partner got his. Both shoot sub 1/2"
 
The .277 Wolverine and the 7mm Valkyrie tie for best named rounds ever!!! I'd go with either for the names alone...

Greg
 
I vote for the Grendel also. I built mine from ground up. Black rain receivers with a Saturn barrel. It loves nosler ballistic tips with Tac powder. Tack driver. My thunderbeast can tightened the group up even more. It's my go to gun
 
adcoch1 said:
I think 6.5 Grendel it is... now to find the best barrel and bolt on a budget...
Click to expand...

The Grendel is probably the best bet for a simple AR15 LR setup. Not as capable or cool as some of the wildcats but has easy to find parts and ammo.
 
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