12.5 Grendel vs 14.5 6mm ARC your opinion counts

justagunguy13 · Apr 10, 2024

Hi everyone, i hope i can get some opinions from all the great minds that frequent this forum. I want to build a short do it all AR, by that I mean target shoot out to 800 maybe 1000yd longest local range is 700, hunt in oregon so maybe 300-400 yd max for white tail maybe elk @ 200-300 yd max, shtf self defense and mildly cqb capable.

I've always wanted a 6.5 Grendel and lately I've just been really infatuated with the ballistics out of 12.5 Grendel. Of course then comes the 6mm ARC and throws a wrench in the works.
My setup would be

Radian 10" ar15 builders Set
Triggertech diamond adjustable 2 stage
Sig tango 1-10 / nightforce nx8 1-8 / primary arms 1-10
Barrel
12.5" rainier ultramatch 6.5 Grendel
Or
14.5" proof carbon 6mm ARC
Sentry 7 gas block
Maxim pdw / HBPDW
I have multiple suppressors i can use

So here is where I want to ask for everyone's opinion, please let me know which one you would choose and why. I have read everything I could find and just want to try and get any input I can before taking this on. Thank you everyone !

oldrifleman · Apr 10, 2024

I had to vote for the Proof as I have had 2 556 Ultramatch uppers from Rainier and have long decided that if it says Rainier I will stay away.

LRRPF52 · Apr 10, 2024

I’ve been shooting Grendel since 2009, and shooting 12” since 2017. Just had it out last week with the kids, the month before, the month before that, etc.

What I’m finding is that the 100gr ELD-VT new load from Hornady really gives you close to or overlapping 6mm ARC performance. The fact that there are 124 factory loads in-production/distribution for 6.5 Grendel from a wide range of manufacturers also is really hard to overcome.

For target work, there are boat loads of different options, with my main one being 123gr ELD-M, but now I’m looking more at getting 100gr ELD-VT for target as well. It’s meant for slaying yotes, but puts down hogs as well.

For big game, 129gr ABLR, 105gr Cavity Back, 123gr SST, 85gr TREX, and a bunch of other factory loads will work within 200yds, especially on cow elk and mule deer. This is from a 16” with 123gr SST on a cow elk at 75yds, DRT, (not my kid):

For CQB, you have faster killing power with much larger wound channels with most of the 6.5mm bullets.

It really checks off all the boxes. My 12” Grendel is my most-preferred AR-15 I’ve ever owned, and I’ve been panic-buying AR-15s since the late 1980s.

LRRPF52 · Apr 10, 2024

For barrels, I would also look at Precision Firearms if you want a nice Criterion for a decent price, or want to step up to Krieger or Bartlein.

I’ve had great results with those, as well as many Lilja drop-in AR barrels.

I have 2x Criterion, 3x Lilja, 1x Faxon, 1x LaRue, 1x Rexus 14.5”, and something else I’m not remembering right now.

No matter what outdoor activity I’m doing, the 12” Grendel with TBAC suppressor gets thrown in the SUV because of how useful and compact it is. 2nd and 3rd ones to go with me for range trips and courses are the 17.6” Lilja and 18” LaRue.

For optics, I think that new Primary Arms 1-10x24 FFP looks really good, but I have no hands-on with it yet.

I’m using Vortex Razor Gen 3 1-10x on the 18” LaRue, and a GRSC Norden Performance 1-6x24 on the 12”.

I just wish I could get the new Vortex Razor AMG 1-10x that is part of the UK Contract KAC KS-1 carbines.

I have used a NF 1-8x NX8 on another 12” Grendel I built for a friend, and it’s a nice combo as well. Very compact and appropriate for the size. Seemed like it was easy for us to both shoot 1 MOA or less groups with it.

justagunguy13 · Apr 10, 2024

LRRPF52 said:
I’ve been shooting Grendel since 2009, and shooting 12” since 2017. Just had it out last week with the kids, the month before, the month before that, etc.

What I’m finding is that the 100gr ELD-VT new load from Hornady really gives you close to or overlapping 6mm ARC performance. The fact that there are 124 factory loads in-production/distribution for 6.5 Grendel from a wide range of manufacturers also is really hard to overcome.

For target work, there are boat loads of different options, with my main one being 123gr ELD-M, but now I’m looking more at getting 100gr ELD-VT for target as well. It’s meant for slaying yotes, but puts down hogs as well.

For big game, 129gr ABLR, 105gr Cavity Back, 123gr SST, 85gr TREX, and a bunch of other factory loads will work within 200yds, especially on cow elk and mule deer.

For CQB, you have faster killing power with much larger wound channels with most of the 6.5mm bullets.

It really checks off all the boxes. My 12” Grendel is my most-preferred AR-15 I’ve ever owned, and I’ve been panic-buying AR-15s since the late 1980s.

Thanks for taking the time and sharing your experience, this is exactly the type of information I was hoping for

justagunguy13 · Apr 10, 2024

oldrifleman said:
I had to vote for the Proof as I have had 2 556 Ultramatch uppers from Rainier and have long decided that if it says Rainier I will stay away.

Thank you for input. I was trying to find a proof carbon 12.5 in 6.5 Grendel, i even called them but its no longer in production.

justagunguy13 · Apr 10, 2024

LRRPF52 said:
For barrels, I would also look at Precision Firearms if you want a nice Criterion for a decent price, or want to step up to Krieger or Bartlein.

I’ve had great results with those, as well as many Lilja drop-in AR barrels.

I have 2x Criterion, 3x Lilja, 1x Faxon, 1x LaRue, 1x Rexus 14.5”, and something else I’m not remembering right now.

No matter what outdoor activity I’m doing, the 12” Grendel with TBAC suppressor gets thrown in the SUV because of how useful and compact it is. 2nd and 3rd ones to go with me for range trips and courses are the 17.6” Lilja and 18” LaRue.

For optics, I think that new Primary Arms 1-10x24 FFP looks really good, but I have no hands-on with it yet.

I’m using Vortex Razor Gen 3 1-10x on the 18” LaRue, and a GRSC Norden Performance 1-6x24 on the 12”.

I just wish I could get the new Vortex Razor AMG 1-10x that is part of the UK Contract KAC KS-1 carbines.

I have used a NF 1-8x NX8 on another 12” Grendel I built for a friend, and it’s a nice combo as well. Very compact and appropriate for the size. Seemed like it was easy for us to both shoot 1 MOA or less groups with

Thank you for taking the time, I will check into precision for sure. I have been reading mixed things on rainier ultramatch but they are supposedly criterion barrels. As to optics yeah there are alot of options I guess.

justagunguy13 · Apr 10, 2024

Does anyone here know what this scope is?

LRRPF52 · Apr 10, 2024

justagunguy13 said:
Does anyone here know what this scope is?

Looks like US Optics to me, but I can’t be sure.

Yup. FDN 10X

LRRPF52 · Apr 10, 2024

I’ve been using tree reticles on my 12” Grendel for shooting 2-3 MOA steel from mostly 400-900yds.

Anything closer is really boring for me, unless shooting small plates, but I really get the most fun out if it center-punching steel in those intermediate-to-long ranges.

For the 17.6” Lilja Wasp Grendel (really lightweight), I’ve been using a Vortex Viper PST 2.5-10x32 and dialing for elevation at distance, which is more precise for sure. It has tracked spot-on for 10 years straight, still holds like it did when I got it.

I’m not a big fan of target knobs without a locking mechanism though.

I’ve been looking at the March 1.5-15x42 for the 17.6” and 18” guns just because my eyes aren’t getting any younger.

The Vortex Razor Gen 3 or a Primary Arms PLxC 1-8x24 would be great on the 12”.

I’m also looking for glass for my 10.5” and 8.5” Grendels.

justagunguy13 · Apr 10, 2024

LRRPF52 said:
Looks like US Optics to me, but I can’t be sure.

Yup. FDN 10X

You are spot on thank you

justagunguy13 · Apr 10, 2024

LRRPF52 said:
I’ve been using tree reticles on my 12” Grendel for shooting 2-3 MOA steel from mostly 400-900yds.

Anything closer it really boring for me, unless shooting small plates, but I really get the most fun out if it center-punching steel in those intermediate-to-long ranges.

For the 17.6” Lilja Wasp Grendel (really lightweight), I’ve been using a Vortex Viper PST 2.5-10x32 and dialing for elevation at distance, which is more precise for sure. It has tracked spot-on for 10 years straight, still holds like it did when I got it.

I’m not a big fan of target knobs without a locking mechanism though.

I’ve been looking at the March 1.5-15x42 for the 17.6” and 18” guns just because my eyes aren’t getting any younger.

The Vortex Razor Gen 3 or a Primary Arms PLxC 1-8x24 would be great on the 12”.

I’m also looking for glass for my 10.5” and 8.5” Grendels.

Great input thank you for all the info. I will look into those, just now I have been looking at US Optics very intriguing.

Shoreglide · Apr 10, 2024

I just installed a Gen3 1-10 on my 12” Grendel. Hope to get some range time with it over the next couple weeks.

MSTN · Apr 11, 2024

In March of 2022 I chronographed three 12.5" 6.5 Grendel, 6.8 SPC, and 6mmARC uppers with factory loads.

6.5 Grendel - Hornady 123 SST - 2280 FPS

6.8 SPC - Remington 115 MatchKing - 2502 FPS (!!!)

6mmARC - Hornady 108 ELD-M - 2509 FPS

These were all new barrels that will speed up a tad with use.

My own 14.5" 6mmARC with a well seasoned Proof CF barrel produced 2560 FPS with that same lot of Hornady ELD-M.

I'm using a Kahles K18i on mine:

It is my #1 do-everything rifle.

LRRPF52 · Apr 11, 2024

Shoreglide said:
I just installed a Gen3 1-10 on my 12” Grendel. Hope to get some range time with it over the next couple weeks.

Did you get the MOA BDC reticle or the Mil Grid tree?

LRRPF52 · Apr 11, 2024

12” Grendel real world velocities for me have been:

2698fps with 90gr TNT Federal factory load
2393fps with 120gr Federal OTM

80gr Hammer HTs do 2750-2840fps from a 12” 6.5 Grendel barrel. That’s better than 20” 5.56 performance, with 8-12ksi less chamber pressure. You have to single load to even shoot 80gr from 5.56 NATO, at 2.390” COL or longer.

I still need to chrono the new 100gr Hornady ELD-VT factory load.

Shoreglide · Apr 11, 2024

LRRPF52 said:
Did you get the MOA BDC reticle or the Mil Grid tree?

It’s an MOA grid. I have Mil for everything else, but I took it in a trade where the deal was well worth it.

TonyTheTiger · Apr 12, 2024

Shoreglide said:
It’s an MOA grid. I have Mil for everything else, but I took it in a trade where the deal was well worth it.

Technically it's not an MOA grid. The horizontal hashes off of center are, but the tree is a BDC not correlated to any measuring system.

Shoreglide · Apr 12, 2024

Doh! You’re right. I probably should have looked a little closer at what was going on.

SBRSarge · Apr 12, 2024

LRRPF52 said:
For barrels, I would also look at Precision Firearms if you want a nice Criterion for a decent price, or want to step up to Krieger or Bartlein.

I’ve had great results with those, as well as many Lilja drop-in AR barrels.

I have 2x Criterion, 3x Lilja, 1x Faxon, 1x LaRue, 1x Rexus 14.5”, and something else I’m not remembering right now.

No matter what outdoor activity I’m doing, the 12” Grendel with TBAC suppressor gets thrown in the SUV because of how useful and compact it is. 2nd and 3rd ones to go with me for range trips and courses are the 17.6” Lilja and 18” LaRue.

For optics, I think that new Primary Arms 1-10x24 FFP looks really good, but I have no hands-on with it yet.

I’m using Vortex Razor Gen 3 1-10x on the 18” LaRue, and a GRSC Norden Performance 1-6x24 on the 12”.

I just wish I could get the new Vortex Razor AMG 1-10x that is part of the UK Contract KAC KS-1 carbines.

I have used a NF 1-8x NX8 on another 12” Grendel I built for a friend, and it’s a nice combo as well. Very compact and appropriate for the size. Seemed like it was easy for us to both shoot 1 MOA or less groups with it.

I second the Precision Firearms barrel suggestion. I have the 13” Criterion in 6mm ARC and it am very happy with it. That, along with my 18” Odin barreled 6ARC does all I’ll ever need from an AR15.

But then I keep reading LRRP’s posts about his short Grendels and start feeling the compulsion to build a Grendel.

Damn you LRRP!

Shoreglide · Apr 12, 2024

LRRPF52 · Apr 13, 2024

I’ve been asking for someone to check my work on this, but really would like a second-look, preferably from someone that’s been shooting LR for 10 years or more and knows their way around ballistics programs and real-world results.

From 18” barrels, Grendel with the 100gr ELD-VT really beats the 6mm ARC 108gr ELD-M, even if we hand-load the 6mm 75fps faster than Hornady’s data up to 24” velocities from Hodgdon’s.

I’m using Hodgdon’s 6.5 Grendel load data for the 100gr Partition (which is harder to drive into the lands) with an average between their CFE223 and LVR data from 24” barrel (2873-2900fps), then run down to 18” velocity of 2750fps through a Grendel internal ballistics engine. I’ve personably loaded the 100gr NBT to 2675fps from a 16” Grendel as well before we had CFE223 or LVR data.

6.5 Grendel 18” barrel, 100gr ELD-VT, 2750fps, .226 G7 Hornady program, 6300ft elevation, 59˚F

600yds 3.7 mils drop 1.1 drift
800yds 6.0 mils drop/ 1.6 drift (592ft-lbs)
1000yds 8.8 mils drop/ 2.1 drift (436ft-lbs)

6mm ARC 24” barrel, 108gr ELD-M, 2650fps hand load, Hornady Doppler Radar Data, 6300ft elev, 59˚F

600yds 4.1 mils / 1.3 drift
800yds 6.8 / 1.9
1000yds 10.2 / 2.6

18” ARC data shows 2575fps max in Hornady’s manual. Seems about right if Hodgdon’s is showing 2650fps from a 24”.

That really kills the ARC in that weight class. ARC is still relevant with the 55-87gr bullets for varmint, but I’m just not seeing the attraction in the 100-110gr class. Let me switch to the 110gr 6mm A-TIP to see if it will do it....

24” 6mm ARC, 110gr 6mm A-TIP, 2650fps Hodgdon’s max data, Hornady Doppler program, same conditions:

600yds 3.9 drop / 1.1 drift
800yds 6.4 drop / 1.6 drift
1000yds 9.5 drop / 2.2 drift 433 ft-lbs

justagunguy13 · Apr 13, 2024

MSTN said:
In March of 2022 I chronographed three 12.5" 6.5 Grendel, 6.8 SPC, and 6mmARC uppers with factory loads.

6.5 Grendel - Hornady 123 SST - 2280 FPS

6.8 SPC - Remington 115 MatchKing - 2502 FPS (!!!)

6mmARC - Hornady 108 ELD-M - 2509 FPS

These were all new barrels that will speed up a tad with use.

My own 14.5" 6mmARC with a well seasoned Proof CF barrel produced 2560 FPS with that same lot of Hornady ELD-M.

I'm using a Kahles K18i on mine:

View attachment 8394073

It is my #1 do-everything rifle.

Thats one nice looking setup. Thank you very much for all the information. I have to admit that 14.5 arc proof keeps calling me more and more.

Goin'Hot · Apr 13, 2024

I just put together a grendel 12.5 rainer ultramatch. The weather has sucked lately so I haven't had a chance to shoot it yet.

LRRPF52 · Apr 13, 2024

The weather you say?

justagunguy13 · Apr 15, 2024

Goin'Hot said:
I just put together a grendel 12.5 rainer ultramatch. The weather has sucked lately so I haven't had a chance to shoot it yet.

View attachment 8396055

Oh wow thats awesome hope you get to go out soon and report back if you wouldn't mind. I'm still as torn back and forth Grendel vs arc what made you choose Grendel?

Macht · Apr 15, 2024

LRRPF52 said:
I’ve been asking for someone to check my work on this, but really would like a second-look, preferably from someone that’s been shooting LR for 10 years or more and knows their way around ballistics programs and real-world results.

From 18” barrels, Grendel with the 100gr ELD-VT really beats the 6mm ARC 108gr ELD-M, even if we hand-load the 6mm 75fps faster than Hornady’s data up to 24” velocities from Hodgdon’s.

I’m using Hodgdon’s 6.5 Grendel load data for the 100gr Partition (which is harder to drive into the lands) with an average between their CFE223 and LVR data from 24” barrel (2873-2900fps), then run down to 18” velocity of 2750fps through a Grendel internal ballistics engine. I’ve personably loaded the 100gr NBT to 2675fps from a 16” Grendel as well before we had CFE223 or LVR data.

6.5 Grendel 18” barrel, 100gr ELD-VT, 2750fps, .226 G7 Hornady program, 6300ft elevation, 59˚F

600yds 3.7 mils drop 1.1 drift
800yds 6.0 mils drop/ 1.6 drift (592ft-lbs)
1000yds 8.8 mils drop/ 2.1 drift (436ft-lbs)

6mm ARC 24” barrel, 108gr ELD-M, 2650fps hand load, Hornady Doppler Radar Data, 6300ft elev, 59˚F

600yds 4.1 mils / 1.3 drift
800yds 6.8 / 1.9
1000yds 10.2 / 2.6

Those velocities should probably be switched. I chronoed the factory ELD-VT at 2630 out of my 18" Grendel and data @Ledzep has posted for the factory 108 ELD-M shows 2750 for a 24" ARC.

LRRPF52 · Apr 15, 2024

I used the data from Hodgdon’s and Hornady for AR-15 pressures.

For 6mm ARC, Hodgdon’s lists 14 powders under the 107gr SMK from a 24” barrel, the fastest being CFE223, AA2520, and LVR.

Hodgdon

CFE 223

2.260"

25.8

2,450

40,300 PSI

28.8

2,687

51,400 PSI

Buy Now

Accurate

2520

2.260"

25.0

2,395

39,700 PSI

28.5

2,672

51,300 PSI

Out Of Stock

Hodgdon

LVR

2.260"

25.4

2,400

37,700 PSI

28.2

2,669

51,800 PSI

For 110gr A-TIP, same thing:

Accurate

2520

2.260"

26.5

2,449

40,100 PSI

28.4

2,656

51,400 PSI

Out Of Stock

Hodgdon

CFE 223

2.260"

25.3

2,397

38,200 PSI

28.2

2,649

50,500 PSI

Buy Now

Hodgdon

LVR

2.260"

25.4

2,410

38,600 PSI

28.2C

2,660

51,200 PS

Those are the speeds I got from my 16” Grendel with 100gr 14 years ago without ever exceeding published max book data at the time. I’ve actually been chasing lower pressure with CFE223 and getting even faster speeds.

Here’s Hodgdon’s 24” data for 6.5 Grendel under 107gr SMK:

Hodgdon

CFE 223

2.250"

29.3

2,489

37,200 PSI

32.2C

2,740

47,500 PSI

Buy Now

Hodgdon

LVR

2.250"

28.8

2,525

35,900 PSI

31.7C

2,753

44,300 PSI

Here it is for the 100gr Nosler Partition (which is harder to drive into the rifling due to the partition wall inside, acts more like a monolith in that regard):

Hodgdon

CFE 223

2.240"

29.5

2,625

39,800 PSI

32.9

2,873

49,500 PSI

Buy Now

Hodgdon

LVR

2.240"

28.2

2,680

42,600 PSI

32.2

2,900

49,800 PSI

LRRPF52 · Apr 15, 2024

Short story is Grendel has more case capacity and more piston area behind the bullet, more bore volume to evacuate pressure at a reasonable rate.

6mm ARC has less case capacity, less piston area, a tighter bore, builds pressure faster, so the window will be narrower for velocity but the same weight bullets have slightly-higher BCs. Advertised BCs seem to be optimistic across a lot of the SKUs and don’t match up with actual Radar data from Hornady.

Once you compare the Radar data with real world data, you see there isn’t much of a difference between 100-110gr between the two, especially with the Grendel’s additional mv at less chamber pressure.

You can also cut and paste the Grendel gas port diameters and locations from 5.56 when setting up a barrel, whereas you want the port farther from the chamber in 6mm due to bore ratio and resulting port pressure.

Goin'Hot · Apr 16, 2024

Finally took it out last night. Shoot a box of Black 123 eldm. It shows promise. They're all moa or better. I was adjusting the bleed off gas block between groups. One thing is for certain. This thing is NOT hearing safe...

Triple D · Apr 16, 2024

LRRPF52 said:
I used the data from Hodgdon’s and Hornady for AR-15 pressures.

For 6mm ARC, Hodgdon’s lists 14 powders under the 107gr SMK from a 24” barrel, the fastest being CFE223, AA2520, and LVR.

Hodgdon CFE 223

2.260" 25.8 2,450 40,300 PSI 28.8 2,687 51,400 PSI Buy Now
Accurate 2520 2.260" 25.0 2,395 39,700 PSI 28.5 2,672 51,300 PSI Out Of Stock
Hodgdon LVR

2.260" 25.4 2,400 37,700 PSI 28.2 2,669 51,800 PSI

For 110gr A-TIP, same thing:

Accurate 2520 2.260" 26.5 2,449 40,100 PSI 28.4 2,656 51,400 PSI Out Of Stock
Hodgdon CFE 223

2.260" 25.3 2,397 38,200 PSI 28.2 2,649 50,500 PSI Buy Now
Hodgdon LVR

2.260" 25.4 2,410 38,600 PSI 28.2C 2,660 51,200 PS

Those are the speeds I got from my 16” Grendel with 100gr 14 years ago without ever exceeding published max book data at the time. I’ve actually been chasing lower pressure with CFE223 and getting even faster speeds.

Here’s Hodgdon’s 24” data for 6.5 Grendel under 107gr SMK:

Hodgdon CFE 223

2.250" 29.3 2,489 37,200 PSI 32.2C 2,740 47,500 PSI Buy Now
Hodgdon LVR

2.250" 28.8 2,525 35,900 PSI 31.7C 2,753 44,300 PSI

Here it is for the 100gr Nosler Partition (which is harder to drive into the rifling due to the partition wall inside, acts more like a monolith in that regard):

Hodgdon CFE 223

2.240" 29.5 2,625 39,800 PSI 32.9 2,873 49,500 PSI Buy Now
Hodgdon LVR

2.240" 28.2 2,680 42,600 PSI 32.2 2,900 49,800 PSI

I’m a bit confused. Why would the comparison not include the 6mm 80gr eld-vt??

LRRPF52 · Apr 16, 2024

Triple D said:
I’m a bit confused. Why would the comparison not include the 6mm 80gr eld-vt??

Because I haven’t recorded my 80gr 6.5 Grendel velocities yet.

18” Grendel will be 3009fps with 80gr Hammer HT.

Looks like 14.5” Grendel will do 2940fps with 80gr.

12” Grendel should do 2782-2880fps with 80gr. My 12" averages 2698fps with 90gr TNT.

10.5” will be at ~2700fps (2654-2753) with 80gr.

Hammer bullets load data for 24” Grendel with 80gr Hammer HT is 3150fps.

Hornady 6mm ARC bolt gun data with 80gr GMX is showing max loads with the fastest powder at 3100fps.

Hornady factory ammo 80gr ELD-VT is showing 3020fps from a 24” test barrel at AR-15 pressures.

justagunguy13 · Apr 16, 2024

Goin'Hot said:
Finally took it out last night. Shoot a box of Black 123 eldm. It shows promise. They're all moa or better. I was adjusting the bleed off gas block between groups. One thing is for certain. This thing is NOT hearing safe...

View attachment 8397981 View attachment 8397982 View attachment 8397983 View attachment 8397984

Thank you very much for sharing that that's awesome valuable information.

LRRPF52 · Apr 16, 2024

I’ve mainly been shooting 123gr ELD-M from my 12” Grendel suppressed as well. Shoots like that, 5rd groups into an inch off rear bag and bipod-supported. I prefer to just take it out to 400 or farther out of the gate and just hit steel at the same ranges I shoot the 18” Grendels. There’s not a lot of difference other than the 12” is a lot shorter and more easy to pack.

Goin'Hot · Apr 16, 2024

@LRRPF52 you're the reason I put this one together...

st1650 · Apr 16, 2024

LRRPF52 said:
I’ve been shooting Grendel since 2009, and shooting 12” since 2017. Just had it out last week with the kids, the month before, the month before that, etc.

What I’m finding is that the 100gr ELD-VT new load from Hornady really gives you close to or overlapping 6mm ARC performance. The fact that there are 124 factory loads in-production/distribution for 6.5 Grendel from a wide range of manufacturers also is really hard to overcome.

For target work, there are boat loads of different options, with my main one being 123gr ELD-M, but now I’m looking more at getting 100gr ELD-VT for target as well. It’s meant for slaying yotes, but puts down hogs as well.

For big game, 129gr ABLR, 105gr Cavity Back, 123gr SST, 85gr TREX, and a bunch of other factory loads will work within 200yds, especially on cow elk and mule deer. This is from a 16” with 123gr SST on a cow elk at 75yds, DRT, (not my kid):

For CQB, you have faster killing power with much larger wound channels with most of the 6.5mm bullets.

It really checks off all the boxes. My 12” Grendel is my most-preferred AR-15 I’ve ever owned, and I’ve been panic-buying AR-15s since the late 1980s.

Also there’s Lapua brass for 6.5 Grendel

st1650 · Apr 16, 2024

LRRPF52 said:
I’ve mainly been shooting 123gr ELD-M from my 12” Grendel suppressed as well. Shoots like that, 5rd groups into an inch off rear bag and bipod-supported. I prefer to just take it out to 400 or farther out of the gate and just hit steel at the same ranges I shoot the 18” Grendels. There’s not a lot of difference other than the 12” is a lot shorter and more easy to pack.

Bastard, now I want a 12in Grendel

LRRPF52 · Apr 17, 2024

If I was told I had to standardize all my AR-15s into one configuration, it would be 12” 6.5 Grendel suppressed.

If I could go back in time for my first Grendel, it would have been 12” instead of 16”. There is no practical difference between them downrange.

justagunguy13 · Apr 17, 2024

LRRPF52 said:
If I was told I had to standardize all my AR-15s into one configuration, it would be 12” 6.5 Grendel suppressed.

If I could go back in time for my first Grendel, it would have been 12” instead of 16”. There is no practical difference between them downrange.

Im pretty decided on the Grendel at this point especially out of the 12.5. Now its just a question which barrel will be good. The rainier ultramatch mod2 is an option I guess a custom krieger is an option from precision firearms. Just big price difference.

st1650 · Apr 17, 2024

LRRPF52 said:
If I was told I had to standardize all my AR-15s into one configuration, it would be 12” 6.5 Grendel suppressed.

If I could go back in time for my first Grendel, it would have been 12” instead of 16”. There is no practical difference between them downrange.

What do you get with 123 factory eldm with the 12in ? 2400 FPS ?

Triple D · Apr 17, 2024

justagunguy13 said:
Im pretty decided on the Grendel at this point especially out of the 12.5. Now its just a question which barrel will be good. The rainier ultramatch mod2 is an option I guess a custom krieger is an option from precision firearms. Just big price difference.

If you’re on the fence for a 6arc, the Rainier Arms 12” shoots the factory 105/108’s at 2365-2390fps iirc.

I’m not exactly a grendel fan. The performance didn’t match my expectations. I sold mine and built a 224Valkyrie. I’ve since added a 12” and 22” 6arc and a 22” 22ARC. I’ve been happy with the decision and downrange performance.

rlsmith1 · Apr 17, 2024

LRRPF52 said:
Because I haven’t recorded my 80gr 6.5 Grendel velocities yet.

18” Grendel will be 3009fps with 80gr Hammer HT.

Looks like 14.5” Grendel will do 2940fps with 80gr.

12” Grendel should do 2782-2880fps with 80gr. My 12" averages 2698fps with 90gr TNT.

10.5” will be at ~2700fps (2654-2753) with 80gr.

Hammer bullets load data for 24” Grendel with 80gr Hammer HT is 3150fps.

Hornady 6mm ARC bolt gun data with 80gr GMX is showing max loads with the fastest powder at 3100fps.

Hornady factory ammo 80gr ELD-VT is showing 3020fps from a 24” test barrel at AR-15 pressures.

The way I compare projectiles between calibers is to try to match BC rather than weight. This allows the larger calibers to take advantage of their larger bore diameter and vice versa for the smaller calibers. There are certainly times where unique bullets in a given caliber can push the envelope, but it's only a matter of time until those designs are available in other calibers with essentially the same performance (the biggest change being made to energy on target).

Personally, I would compare the 100 ELD VT in 6.5G to the 80 ELD VT in 6arc because they are similar bullets driven at the upper end of the velocity range. Will the ARC give up long range performance? Sure, but that's already understood as energy on target is less with the ARC (due to lighter bullet weight). Therefore, I would expect the ARC to be a better performer at closer ranges while the Grendel does better further out. It is up to the shooter which range is more important to them.

For me, I would rather a slightly flatter bullet inside 400 yds for coyotes at night, but you seem to prefer the performance at 700+ which lends better to the Grendel. This is not to say the Grendel is not a good performer at 400 (it has more energy for sure), but it may not be as flat which is more important to me as both cartridges will have enough energy on target for yotes.

LRRPF52 said:
Short story is Grendel has more case capacity and more piston area behind the bullet, more bore volume to evacuate pressure at a reasonable rate.

6mm ARC has less case capacity, less piston area, a tighter bore, builds pressure faster, so the window will be narrower for velocity but the same weight bullets have slightly-higher BCs. Advertised BCs seem to be optimistic across a lot of the SKUs and don’t match up with actual Radar data from Hornady.

Once you compare the Radar data with real world data, you see there isn’t much of a difference between 100-110gr between the two, especially with the Grendel’s additional mv at less chamber pressure.

You can also cut and paste the Grendel gas port diameters and locations from 5.56 when setting up a barrel, whereas you want the port farther from the chamber in 6mm due to bore ratio and resulting port pressure.

Totally agree here, and as a general rule of thumb I try to set up my shorter barreled rifles with larger caliber cartridges to minimize velocity loss

Goin'Hot · Apr 17, 2024

st1650 said:
What do you get with 123 factory eldm with the 12in ? 2400 FPS ?

This is what I got out of my 12.5". 70° 1000' altitude.

LRRPF52 · Apr 17, 2024

Triple D said:
If you’re on the fence for a 6arc, the Rainier Arms 12” shoots the factory 105/108’s at 2365-2390fps iirc.

I’m not exactly a grendel fan. The performance didn’t match my expectations. I sold mine and built a 224Valkyrie. I’ve since added a 12” and 22” 6arc and a 22” 22ARC. I’ve been happy with the decision and downrange performance.

My initial experience with 6.5 Grendel was not impressive. I was shooting .260 Rem primarily at the time, so I was used to pretty high velocities with 130gr VLDs. I thought I would land on sixes as a special snowflake and immediately get great results with 123gr Scenars from a 16 Grendel hand-loading for it out of the gate using Vihtavuori powders.

Once I got on the Grendel Forum and got some advice from guys who had been reloading for it from the start, I started seeing MV I was looking for, but I still didn’t realize its potential at distance yet. I was mainly listening to those who said it was good out to 600yds and that’s about it, so I really didn’t even shoot it much past 300-400yds.

Some yahoos came out to one of the spots I liked shooting in the West Desert and told me they would be shooting over our heads with Glocks out to 800yds, not to worry, “the guy who trains all the Marine snipers is teaching us long range". I said don’t do that, let us pack up and get out of here before they commenced their madness. I stopped by to see what kind of shenanigans they were doing, and there was some guy behind a spotting scope trying to walk guys into a target at 1200yds. They were shooting 30-378 Weatherby, 300 Win Mag, .308, things like that in Fudd set-ups with 3-9xs, Uncle Mike’s shell holders, you get the picture.

They asked if I wanted to take a swing at it, so I made some excuses, then pretended to acquiesce, got in the back of the truck to pull out the 16” Grendel. I plugged in 1200yds into Strelok to see what my drop and drift would be, and it was something like 14.4 mils.

I set-up on some guy’s truck hood with my rear bag, maxed out my elevation to 12 mils and then used the mil hashes in the reticle for the rest, 1st round was barely off the left edge based on my wind call, and I put the rest on-target as fast as I could re-index and break the shots. They hadn’t been hitting it at all of course since nobody among them had any formal LR experience.

I went home thinking I need to re-look at this cartridge, get an upper-tier barrel and build it up, so when the Lilja group buy came along, I ended up with my 17.6” pipe and built off that. I spent the next 3 years shooting it for anything where I was doing LR work and got to know the performance even more with that set-up. I did the 16” in 2009, and the Lilja 17.6” in 2014.

If you want 6mm performance, the 100gr ELD-VT and 105-107gr Sierras are really close/overlap 6mm. Hand-loaded, they exceed what 6mm can do, especially using LVR and CFE223. They also will do that with 5,000-8,000psi less chamber pressure.

LRRPF52 · Apr 18, 2024

justagunguy13 said:
Im pretty decided on the Grendel at this point especially out of the 12.5. Now its just a question which barrel will be good. The rainier ultramatch mod2 is an option I guess a custom krieger is an option from precision firearms. Just big price difference.

You can also do a Criterion for $425 from PF.

Someone had a complete PF Bartlein 12” Grendel with billet receivers for a great price not too long ago. I just checked and the listing is gone now.

justagunguy13 · Apr 18, 2024

LRRPF52 said:
My initial experience with 6.5 Grendel was not impressive. I was shooting .260 Rem primarily at the time, so I was used to pretty high velocities with 130gr VLDs. I thought I would land on sixes as a special snowflake and immediately get great results with 123gr Scenars from a 16 Grendel hand-loading for it out of the gate using Vihtavuori powders.

Once I got on the Grendel Forum and got some advice from guys who had been reloading for it from the start, I started seeing MV I was looking for, but I still didn’t realize its potential at distance yet. I was mainly listening to those who said it was good out to 600yds and that’s about it, so I really didn’t even shoot it much past 300-400yds.

Some yahoos came out to one of the spots I liked shooting in the West Desert and told me they would be shooting over our heads with Glocks out to 800yds, not to worry, “the guy who trains all the Marine snipers is teaching us long range". I said don’t do that, let us pack up and get out of here before they commenced their madness. I stopped by to see what they kind of shenanigans they were doing, and there was some guy behind a spotting scope trying to walk guys into a target at 1200yds. They were shooting 30-378 Weatherby, 300 Win Mag, .308, things like that in Fudd set-ups with 3-9xs, Uncle Mike’s shell holders, you get the picture.

They asked if I wanted to take a swing at it, so I made some excuses, then pretended to acquiesce, got in the back of the truck to pull out the 16” Grendel. I plugged in 1200yds into Strelok to see what my drop and drift would be, and it was something like 14.4 mils.

I set-up on some guy’s truck hood with my rear bag, maxed out my elevation to 12 mils and then used the mil hashes in the reticle for the rest, 1st round was barely off the left edge based on my wind call, and I put the rest on-target as fast as I could re-index and break the shots. They hadn’t been hitting it at all of course since nobody among them had any formal LR experience.

I went home thinking I need to re-look at this cartridge, get an upper-tier barrel and build it up, so when the Lilja group buy came along, I ended up with my 17.6” pipe and built off that. I spent the next 3 years shooting it for anything where I was doing LR work and got to know the performance even more with that set-up. I did the 16” in 2009, and the Lilja 17.6” in 2014.

If you want 6mm performance, the 100gr ELD-VT and 105-107gr Sierras are really close/overlap 6mm. Hand-loaded, they exceed what 6mm can do, especially using LVR and CFE223. They also will do that with 5,000-8,000psi less chamber pressure.

Thank you very much for sharing all that it just kind of reinforces my decision to go with the grendel

LRRPF52 · Apr 18, 2024

rlsmith1 said:
The way I compare projectiles between calibers is to try to match BC rather than weight. This allows the larger calibers to take advantage of their larger bore diameter and vice versa for the smaller calibers. There are certainly times where unique bullets in a given caliber can push the envelope, but it's only a matter of time until those designs are available in other calibers with essentially the same performance (the biggest change being made to energy on target).

Personally, I would compare the 100 ELD VT in 6.5G to the 80 ELD VT in 6arc because they are similar bullets driven at the upper end of the velocity range. Will the ARC give up long range performance? Sure, but that's already understood as energy on target is less with the ARC (due to lighter bullet weight). Therefore, I would expect the ARC to be a better performer at closer ranges while the Grendel does better further out. It is up to the shooter which range is more important to them.

For me, I would rather a slightly flatter bullet inside 400 yds for coyotes at night, but you seem to prefer the performance at 700+ which lends better to the Grendel. This is not to say the Grendel is not a good performer at 400 (it has more energy for sure), but it may not be as flat which is more important to me as both cartridges will have enough energy on target for yotes.

Totally agree here, and as a general rule of thumb I try to set up my shorter barreled rifles with larger caliber cartridges to minimize velocity loss

What I’m seeing is that for short range with lighter bullets of the same weight, Grendel also has more mv and flatter trajectory, it’s just that the 6mm has factory bullet options ranging in weights from 55gr-75gr that don’t exist in 6.5mm. Lowest 6.5mm weight is 80gr Hammer HTs.

In the 6mm ARC, COL is really short with the lightweight bullets, as it’s meant more for the 103-110gr class. I’ve always liked 6mm AR with 107s (simple neck-down from Grendel), but once I started seeing more what 100-110gr do in Grendel, my plans for a 6mm faded away.

For the yote hunters, you’re not going to see much difference as a shooter between 80gr Hammer HTs or 95gr V-MAXs in 6.5 Grendel vs 75-87gr in 6mm. Trajectories are going to be mostly academic at that point. In fact, you can match or exceed the 6mm mv from shorter barrels in 6.5 Grendel using LVR or CFE223, but the 6mms will make up for it at 400yds with BC. This comes into play for me when shooting suppressed and not wanting a lot of extra length on the carbine. We’re talking a spread in BCs between .365 to .406 G1, if advertised BCs mean anything.

A 14.5” Grendel with 80gr Hammers will do ~2900fps.

An 18” ARC will do 2800fps with the 80gr GMX and 2850fps with the 90gr ELD-X, per Hornady’s 18” AR max load data.

That 6mm 90gr ELD-X is a great bullet for short range hunting and long range target, supersonic out to 900yds from an 18” ARC.

The main varmint bullets for Grendel are:

90gr TNT
95gr V-MAX
95gr Varmageddon
100gr ELD-VT

Each one of those has a factory ammo option as well.

For 6mm ARC, you can hand-load a lot of varmint bullets ranging from 55-87gr. Factory ammo for varmints in the ARC include:

58gr V-MAX
75gr V-MAX
80gr ELD-VT
87gr V-MAX

justagunguy13 · Apr 18, 2024

LRRPF52 said:
What I’m seeing is that for short range with lighter bullets of the same weight, Grendel also has more mv and flatter trajectory, it’s just that the 6mm has factory bullet options ranging in weights from 55gr-75gr that don’t exist in 6.5mm. Lowest 6.5mm weight is 80gr Hammer HTs.

In the 6mm ARC, COL is really short with the lightweight bullets, as it’s meant more for the 103-110gr class. I’ve always liked 6mm AR with 107s (simple neck-down from Grendel), but once I started seeing more what 100-110gr do in Grendel, my plans for a 6mm faded away.

For the yote hunters, you’re not going to see much difference as a shooter between 80gr Hammer HTs or 95gr V-MAXs in 6.5 Grendel vs 75-87gr in 6mm. Trajectories are going to be mostly academic at that point. In fact, you can match or exceed the 6mm mv from shorter barrels in 6.5 Grendel using LVR or CFE223, but the 6mms will make up for it at 400yds with BC. This comes into play for me when shooting suppressed and not wanting a lot of extra length on the carbine. We’re talking a spread in BCs between .365 to .406 G1, if advertised BCs mean anything.

A 14.5” Grendel with 80gr Hammers will do ~2900fps.

An 18” ARC will do 2800fps with the 80gr GMX and 2850fps with the 90gr ELD-X, per Hornady’s 18” AR max load data.

That 6mm 90gr ELD-X is a great bullet for short range hunting and long range target, supersonic out to 900yds from an 18” ARC.

The main varmint bullets for Grendel are:

90gr TNT
95gr V-MAX
95gr Varmageddon
100gr ELD-VT

Each one of those has a factory ammo option as well.

For 6mm ARC, you can hand-load a lot of varmint bullets ranging from 55-87gr. Factory ammo for varmints in the ARC include:

58gr V-MAX
75gr V-MAX
80gr ELD-VT
87gr V-MAX

Thank you again very much for sharing so much information and experience, Being honest with myself I'm working a lot these days and don't have much time for reloading at the moment but plan to in the future so the Grendel Definitely seems to fit what I want Definitely seems to fit what I want. Especially with those 100 gr eldvt. I have Pretty much all the lower grain stuff up to 75gr covered in various 223 rifles. I want this one to be Contact suppressed And I want to be able to grab it to shoot some hugs To shoot a deer little bit far away potentially To shoot some coyotes on occasion And as Defense role That crosses into dmr. So I think That's gonna hit the mark for me.

rlsmith1 · Apr 18, 2024

LRRPF52 said:
What I’m seeing is that for short range with lighter bullets of the same weight, Grendel also has more mv and flatter trajectory, it’s just that the 6mm has factory bullet options ranging in weights from 55gr-75gr that don’t exist in 6.5mm. Lowest 6.5mm weight is 80gr Hammer HTs.

In the 6mm ARC, COL is really short with the lightweight bullets, as it’s meant more for the 103-110gr class. I’ve always liked 6mm AR with 107s (simple neck-down from Grendel), but once I started seeing more what 100-110gr do in Grendel, my plans for a 6mm faded away.

For the yote hunters, you’re not going to see much difference as a shooter between 80gr Hammer HTs or 95gr V-MAXs in 6.5 Grendel vs 75-87gr in 6mm. Trajectories are going to be mostly academic at that point. In fact, you can match or exceed the 6mm mv from shorter barrels in 6.5 Grendel using LVR or CFE223, but the 6mms will make up for it at 400yds with BC. This comes into play for me when shooting suppressed and not wanting a lot of extra length on the carbine. We’re talking a spread in BCs between .365 to .406 G1, if advertised BCs mean anything.

A 14.5” Grendel with 80gr Hammers will do ~2900fps.

An 18” ARC will do 2800fps with the 80gr GMX and 2850fps with the 90gr ELD-X, per Hornady’s 18” AR max load data.

That 6mm 90gr ELD-X is a great bullet for short range hunting and long range target, supersonic out to 900yds from an 18” ARC.

The main varmint bullets for Grendel are:

90gr TNT
95gr V-MAX
95gr Varmageddon
100gr ELD-VT

Each one of those has a factory ammo option as well.

For 6mm ARC, you can hand-load a lot of varmint bullets ranging from 55-87gr. Factory ammo for varmints in the ARC include:

58gr V-MAX
75gr V-MAX
80gr ELD-VT
87gr V-MAX

I hear you on reloads, but I'm trying to stay away from that if possible. Which thread did you post all the factory loadings for the 6.5G in?

LRRPF52 · Apr 18, 2024

justagunguy13 said:
Thank you again very much for sharing so much information and experience, Being honest with myself I'm working a lot these days and don't have much time for reloading at the moment but plan to in the future so the Grendel Definitely seems to fit what I want Definitely seems to fit what I want. Especially with those 100 gr eldvt. I have Pretty much all the lower grain stuff up to 75gr covered in various 223 rifles. I want this one to be Contact suppressed And I want to be able to grab it to shoot some hugs To shoot a deer little bit far away potentially To shoot some coyotes on occasion And as Defense role That crosses into dmr. So I think That's gonna hit the mark for me.

If you want an easy button in 2 different loads, you could do 100gr ELD-VT and 123gr ELD-M, done.

100gr ELD-M seems like it would be nasty in close quarters, since it’s a varmint round.

It has already been used to take hogs and exhibits explosive results as designed, but I think it’s meant more for yotes.

123gr ELD-M has been used a lot for medium game hunting and does a good job of it since it’s a bit softer than a 123gr SST, but jacket separation is common from longer barrels/closer shots. Still plows through the vitals.

123gr ELD-M hits the steel hard even from the 12”. It has more energy at 400yds than a 20” .30-30 Winchester does at 200yds.

Another premium load that does really well on larger game is the 129gr Nosler Accubond Long Range. PF and Nosler both load it but it sells out within 24hr usually.

For bolts, the Rexus bolts are my go-to.

Bootleg Bolt Carrier allows you to dial-in the gas setting to prevent early unlocking. I expected to have problems with 12” CLGS, but that Bootleg carrier really works at taming the little gun.

I also use an extra power action spring with standard carbine buffer. 12” guns run great with these components. I shoot it exclusively suppressed.

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