Second rifle/upper after 556 - 6.5 Grendel, 300 Blackout, or ... ?

[Sblzrd65]

Looking for some advice and perspective. For one getting into ARs more, after the first 556 (16" barrel, normal stock), what's a good option for the next upper? Not looking to go SBR, not looking to add a pistol brace (assuming the alphabet agencies will be cracking down on them.) Have shot 300 Blackout before and enjoyed it so that'd be my first thought. Added bonus of using the same magazines as well. Currently though, the ammo is neigh impossible to find so it's got me looking around at other options. The 6.5 Grendel caught my eye as something for more long distance as an add on. Are there any other options to consider? Thinking the plan is to just buy completed uppers instead of tinkering around.

[Ronin]

I don't see a point to a .300BLK rifle. The cartridge was designed to work with a 9" barrel. Almost anything factory shot from a 16"+ .300BLK will be supersonic, even subsonic ammo, so it defeats the point of suppressing it. 6.5 Grendel is an excellent alternate rifle upper, though some barrels are more picky about ammo than others. Still it can hit out to 1k yards with the right ammo and barrel.

[DucatiRon]

6.5 Grendel or 6 ARC from Hornady are the two most capable calibers you can get in an AR-15. I personally have the 6.5 G but since the 6 ARC came out that would be my my choice on a new build.

[Boo Vuccla]

Ditto on 6.5 Grendel. The ARC is very capable also and has some backing from the industry so it isn't going to go away but I have Grendels and just love them. Very accurate but I handload. Not sure between both the Grendel or ARC if I would plunge into it with the current state of affairs if I didn't already have what I need to feed one or the other. Hard decision right now though as long as there is demand, the industry will try to fill it. But......remember that when that same industry is draining your wallet at the same time!

[Ecclectic Collector]

The nice thing is you have so many options. You can consider going the route of multiple calibers, or dedicated uppers for specific roles.

Think like this: your 5.56mm is your self defense/military compatible upper. A 6mm ARC, 6.5 Grendel or 6.8m SPC gives you a medium game/long range capable gun. Adding a third in one of the big bore options like .350 Legend, or one of the .450s and even .50 caliber gives you a serious brush gun for hogs and the like.

Since uppers are not technically firearms you can mix and match all on the same lower as your interest/role demands. You can also purchase or sell uppers without needing anybody's say so.

[wanneroo]

I'm a big proponent of 300 Blackout as I have discussed in other threads.

First thing you need to do with that is dispense with the commonly told wisdom of "300 Blackout is only optimized for 9 inch barrels". Maybe that was case at some point but no more.

300 Blackout has more ammo choices than 6.5 Grendel. Of course Grendel is more of a medium range cartridge and 6 ARC even longer.

Really to save money with any of these choices, reloading/handloading is where it is at.

[Emptymag]

9mm AR15 carbines are a lot cheaper to shoot.

Oh, wait.


I love my 7.62x39 AR15s.

Here's a long, long, LONG list of potential AR15 calibers...
https://en.wikipedia.org/wiki/List_o...orm_cartridges

[red dog]

Here*s a thought, with times as they are how about a dedicated .22 upper? Lower ammo costs, more likely to practice more. Better accuracy than the conversions out there. Great for a critter glitter. And the best part it*s just plain fun.

[aubie515]

Some good suggestions in this thread. I own a few 6.5G and 300BO guns, so I'd say both are capable and it will depend on your usage. Honestly, with ammo availability where it's at, I'd stick with 223 or 22LR. Even if you reload, primers, powder and bullets are tough to get and that doesn't seem to have an end date. If you already had the reloading components, we would be having a different conversation.

The big pro with 300BO is it's very quiet if you are using subsonic ammo with suppressor. I gave my 300BO bolt rifle to my daughter since she's petite and hunts with it and it's the perfect caliber for her since it's so damn quiet.

The big pro for 6.5G is that it will shoot further in an AR15 sized frame. It's nice to have a smaller rifle capable reaching 1k yards in a light weight package, but you can do the same thing with an AR10 if you dump enough money to make it light weight.

[MMH]

You are getting good advice in this thread. Two things that you should consider:

1.) Do you reload?
With either cartridge you better, or things will get expensive and you will not have the flexibility to do what you want to do. If you do not reload, I think that the 300blk will have more availability, options, and be cheaper (is is getting more popular). Another advantage of 300blk is brass availability. And, if you cannot find any, you can always make some by fire forming 5.56 brass, and you always find 5.56 stuff. Also, while not related to reloading, but along the same lines of SHTF reasoning, with the exception of the barrel, all parts in a 300blk rifle are identical to the 5.56 rifle. The Grendel will need its own special bolt and magazines.

2.) What are your objectives: short/intermediate range (up to 400 yards) or intermediate /long range (400 to 1000 yards).
This gets into what kind of rifle you plan to shoot (CQB M4 type or long range precision rifle). If shooting a small CQB carbine, then I would lean towards the 300blk. Sure the Grendel is ballistically superior, but the 300blk can really do anything that the Grendel can at these ranges. One exception is if you intend to hunt deer size game. Personally, I wouldn't shoot at a deer w/ a 300blk past 250 yards or so. The Grendel has more energy and I would be comfortable out to 400 yards.
If shooting long range, then clearly the Grendel would be a better choice. At 600 yards, it would perform as well as a 5.56 but we are talking about precision rifle here - big heavy guns. Also, with the 5.56 my assumption is that you are shooting handloads & heavy match bullets (75 grain or so). My 600 yard AR has a 22" heavy barrel and weighs 11 lbs. I would expect the Grendel to do about as well as the 5.56, but not better. The 300blk can be taken to 600 yards (maybe more?), but the Grendel could go to 1000. Sometimes I shoot my 5.56 at 1000 yards, I do OK, but do much better with even a meager .308. Again, I would expect the Grendel to perform similarly to the 5.56. It would be fun for sure, but there are better choices if shooting 1000 yards.

There is good information in the 5.56 vs. 300blk thread: http://forum.pafoa.org/showthread.php?t=364152
Unfortunately the thread devolved into a pissing contest, but still, there is a lot of good info.