So I have a very cool AR-15 Saint Edge pistol in 223.  It's a blast to shoot.  The only problem is I want to take it on a hog hunt with my buddies and I want something with more power to take down the big hogs.  So I started researching and I found that the 300 Blackout is great in these shorter barrel configurations and has the power I need.  Then I found great information on the 6.5 Grendel which sounds like a superior hunting round.  

Can someone orient me one way or another?  Is there any reason to go with the 300BLK over the 6.5 Grendel or vice versa in the shorter barrel configuration I am going to continue using?  (I'm not interested in suppressing the gun or subsonic ammo)

I appreciate your opinions!

With a 16" barrel, assuming a 110 @ 2350 from the blackout and a 123 @ 2450 from the Grendel, and a 4-inch "point blank" target, the blackout is point blank out to about 205 yards, the Grendel to about 215.  A shorter barrel you'll have even less noticeable difference.

If you *WANT* a Grendel go for it (hell, I did....and I hunt with my blackout a LOT )  But you won't see a huge difference given equal barrel lengths between the two at MOST hunting ranges.

That being said the Grendel would be a much better 400-500 yard hunting setup than the Blackout.  But if we're talking quick shots, stalking to within a couple hundred yards, not perched somewhere dialing in your dope....you'll not see much if any difference between the two.

So I ended up getting the PSA 10.5" upper in 300BLK.  

I put it on my Saint Edge Pistol lower with some iron sights and a Romeo5 red dot...looks amazing.  

The only issue I have with the PSA upper is that the barrel identification is obscured by the handrail so I cannot visually confirm the caliber of the barrel.  It's not an issue because my 223 has clear labeling and looks quite different but a little bit annoying since I know how important it will be to keep ammo separate in this gun.  I have to trust the box it came in from PSA and that's a little unnerving but the barrel is definitely larger than my 223.

I grew up hunting in GA with a Marlin 3030 and had always been fascinated by the AR platform but never took the time to learn about it.  Now with all this time on my hands, all I do is read and learn.  

I'm wondering...Will the Saint Edge Pistol lower work well with the PSA 10.5" upper?  It seems to be a perfect fit.  The quality of the PSA upper looks very good.

Any thoughts on mixing and matching a Springfield lower with a PSA upper or other issues I need to be aware of?

Your SE lower should be fine.
Mix upper/lower as you want you should have no issue.  Mark your mags so they are unique to the 300bo, and for gods sake keep your ammo separated.  Don't let others load up unless you are eagle eyeing them, to the untrained and even the trained distracted this is how one puts a 300bo in 5.56 chambered gun and gets unintended consequences.  

Topic Moved

Go with the 6.8spc 10.5-12.5”barrel
Flatter shooting and more energy than 300

Place the upper and mags on piece of cardboard and lay  a sniper veil scarf over them and hit it with your favorite color of Krylon.
Dry, reverse sides, repeat.

OP-your Springfield lower should work just fine for your PSA upper

The other guy had it right concerning your ammo:

1) buy a cheap dust cover marked .300blk for your upper
2) buy some lancer .300 blk mags.  They're also clearly marked. OR, buy some of those rubber band indicators that list .300 blk on them that slide around your mag.

You'll be doubly reminded on your ammo caliber that way.

Cool idea on color coding. Might hafta do something like that when I start adding 6mmARCs to my Grendels.

I second this. Never understood why people build 6.5 Grendel pistols/SBRs when 6.8 SPC does better out of the shorter barrel. The Grendel can't use the long, heavy bullets that made the Creedmoor successful either.

Mute point, OP went the blackout route, but the 6.5 or 6.8 both dust the BO in performance unless you can it and go for hollywood quiet.

6.8 and 6.5 both do just fine out of short barrels.  But OP went Blackout, so this info is mostly for others going through similar dilemmas.

Not true.  Johnny's Reloading Bench has had very good results with 140 grain Hornady BTHP Match.  I'll be trying the 140 grain Speer Gold Dots in my rifle in a few weeks hoping for similar results.

Here's the video of his loads which showed exceptional accuracy out of his rifle.


https://www.youtube.com/watch?v=OGj7J6Dnw2w&list=PLTTrjvDib94lsYdUzKqlh4cjTRb-JJmto&index=22

Because 6.8 doesn't do better out of a shorter barrel, just like a 16" or 18" barrel.

Sure, you can hot-load it for more muzzle velocity, but that muzzle velocity will not translate to the same retained energy downrange because the projectiles are not anywhere near as efficient.

If you hand-load for one, then you need to compare hand-loading for the other.

Even without hand-loading, I'm getting 2400fps mv with 120gr Federal factory ammo from my 12" Grendel, and 2700fps with 90gr TNT factory ammo.

Also, Grendel was developed with use of the 6.5mm long, heavy bullets before 6.5 Creedmoor even existed, and the data for those loads was published well before 6.5CM was introduced.

These include 130gr Berger VLD, 130gr Norma Golden Target, 140gr Lapua Naturalis, 140gr Berger VLD, 139gr Scenar, 144gr Lapua FMJ, and 156gr Lapua Mega.

You won't shoot them anywhere near the same speeds as 6.5CM or .260 Rem, but they do a lot better than you might think.

When I compare my 22" .260 Rem to my 22" 6.5 Grendel, I lose about 175-225yds of supersonic reach, no matter what bullet it is.  With any of the higher BC bullets like the 130gr VLDs and longer, both rifles are supersonic well past 1300yds for me.  Shooting at 1000yds with either rifle using higher BC bullets like the Bergers isn't a challenge unless the wind exceeds 15mph full value, then your hit probability on man-sized silhouettes starts to drop and the effective range pulls back to around 800yds even with the .260 Rem or 6.5CM for 1st-round connect.  In 10mph or less winds, both are surprisingly-capable out to 1300yds at 4400ft elevation.  Once you get higher in the 6000ft or more bands, it gets even better.  Down at sea level, you're fine to 1000yds and will have a hard time finding ranges that go out to 1000yds in your area.

The question for me then was, "Is it worth having to go up to the larger frame, low brass life, must trim brass, heavy weight, more recoil, less sight picture stability AR10?"

The answer for me was, "Sometimes, though not often."  I haven't shot my .260 Rem in a long time now.

I honestly haven't shot 22" Grendel in a long time either, because 18" and shorter do really well for me even out to 1000yds.

The same things that make this possible also work at closer range when looking at velocity loss, so the velocity loss with the Grendel is flatter if you were to graph the 2 out.

For hunting within 200yds, I doubt you'd be able to see much difference, other than with 6.5mm, you have a lot more projectile selection and a lot of loads that are above 120gr, whereas with 6.8, the average projectile weight with factory ammo is 102gr.  

Most of the .277" bullets on the market can't be used inside the 6.8's COL and case length/magazine length limitations in the AR15, since they were made for the .270 Winchester, .270 Weatherby, and .270 Winchester Short Magnum.

Just like the claims about 6.8 being better in 16" barrels were erroneous, the claims about short barrels are incorrect as well.

It's not bad, but you aren't gaining any practical advantages over short barreled 6.5 Grendels.

Then there is the issue with ammunition costs.

With PPU and S&B Grendel ammo now, along with the 90 other factory options that also include Wolf, it's becoming harder to make a case for the 6.8 SPC.

2 areas that I've seen people mention that still make it a better option for them are local gun store ammo availability and magazines.

Those are usually determined by what area you live in and how cheap you went on a DIY build.

Being that the OP went with the .300blk...the 6.8 vs 6.5 debate can now be summed up in two gifs.

I think the OP made the right choice for his needs.
I shoot 6.5g out of 20” & 12” barrels and .300bo out of 16” & 8”.
Beyond steel case 6.5G most commercial loads are a buck a round.
Then there’s bolts & mags, I’ve run lots of different commercial loads thru 5.56 PMAGs, Lancers, E-landers, Surefeed, Brownells GIs, D&H and those Bulgarian steel mags, no feed issues. Got a spare 5.56 bolt? It’s your spare .300bo too.
There’s only a few good mag options for 6.5G.

I run tan furniture on both of my .300bos and keep dedicated .300bo mags marked with tan spray paint and ‘300bo’. Ammo & mags are stored in separate ammo cans.