Grendel Advice...

jamcoconut1097

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Minuteman
Nov 10, 2013
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Formulating a plan as to what I'm gonna do with my AR-15 build. I know I want to do 6.5 Grendel because I want a longer range AR-15 to take to the range but I may want to take it hunting as well. I want accurate but light. All I have right now are the upper and the lower so any suggestions would be helpful. Barrel length, contour, fluting...all up in the air. Scope & mount/rings are too. Handguards...everything. Looking forward to the responses!
 
How far will you be shooting and do you reload?

I went with a Lilja 20" ar740 contour, fluted, with a Ross Schuler muzzle brake and have been extremely happy with it. Topped it off with a Nightforce nxs 5.5-22. It's not light weight by any means though.

The grendel is a great little cartridge and one of my favorite to shoot. I've had great success with 8208 xbr behind 123 grain amax.
Now if I only knew where to get more 123 grain amax bullets.....
 
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The 123 grain amax and sst factory ammo both shoot well in mine, not as good as hand loads , but still pretty good. Like BC83 said, check out Precision Firearms. They do make some good loads for the Grendel.

I chose the 20" barrel because I don't hunt with it and most times I am shooting steel at 400-1000 yards. So, no, 18" barrel is not too short. Even a 16" barrel will likely meet your needs.
 
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Haven't read much about 6mm. How well does it do when hunting deer?

I'm pretty sure plenty of deer have been killed with .243 Remington. Killing them with a 6mm AR-15 of some kind would probably have the same result, but the effective range might be shorter due to lower powder capacity.

6mm puts you in with the Big Block AR's, I would stick with the Grendel it's an awesome round..

Im a Huge fan of the Grendel ill do my best to help you, but i need to know your budget???

Also what upper and lower are you working with??

Wrong. Grendel is effectively a 7.62x39 necked down to 6.5 mm. There are a number of 7.62x39-based cartridges that use a 6 mm bullet. It's basically the same idea as the 6.5 Grendel, but the 6mm bullet makes better use of the available powder capacity.

Don't get me wrong--6.5 Grendel is basically a .308 in an AR-15. But 6mm bullets in the same brass is a better fit.

You are correct that you can get a .243 in the DPMS LR series of rifles, but that is not what I was talking about. I am talking about an AR-15 length cartridge with a 6mm bullet.

There is also the 6x45 cartridge, which I do not think is all that useful because, like with Grendel, the powder capacity is too low for the bullet diameter, but its existence also negates your suggestion that one needs to have a big AR to shoot a 6mm bullet. A 6x45 is just a .223 rem necked up.

Rather than posting this, I should just build one myself and not tell anyone....but if you search back through some posts for 6mm AR stuff there was a guy building some uppers a few years ago.
 
I'm a Grendel nut too. I'm on my second build. I'm running a 20" Satern 1:8 twist. Shoots the 123 Amax at 2450. By far my favorite rifle. Planning to hunt whitetail with it in Nov. I ran it out to 750 yards with no issues. Consistent hits on ISPC sized plates. Tan out of elevation so I had to get a 20 MOA mount. Now I figure I'm good out to 1k.

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I'm a Grendel nut too. I'm on my second build. I'm running a 20" Satern 1:8 twist. Shoots the 123 Amax at 2450. By far my favorite rifle. Planning to hunt whitetail with it in Nov. I ran it out to 750 yards with no issues. Consistent hits on ISPC sized plates. Tan out of elevation so I had to get a 20 MOA mount. Now I figure I'm good out to 1k.

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That is a sick rifle. Details?
 
Having built three and tested extensively, I can say this:

Whatever you get, get a barrel with a rifle length gas path. I had to back off my load one grain to accommodate a mid-length gas path in an 18" barrel. I'm getting nearly the same velocity though in my mid length gas/18" barrel as I did with my 24" barrel with rifle gas path. The drop in velocity is about 80 fps and is expected.

A couple notes here:
Once the bullet goes past the gas port, the gasses pushing on it do very little. So, the most important thing is gas path length. The 2" from rifle to mid-length are basically the same as having a shorter barrel in a bolt gun.

The Grendel/6mmAR/6PPC all have about 20 percent more capacity than does the .223/5.56 NATO, Which the AR-15 platform was designed around. This needs to be dealt with so as not to produce too much pressure back on the BCG. Too short of a gas path this will produce too much pressure at the BCG, causing it to open too soon. This causes case head swipe. Because of too high/too soon pressure coming back through the gas path. Why I suggest the long length platform. Also having a controllable gas port, or smaller gas port, helps. Another thing that cause case head swipe is too slow of a powder charge. AA2520 is notorious for this in widely changing temps. The best powder to run IMO is IMR 8208XBR.

As far as the 6mm's go, R. Whitley is the one who developed the 6mm AR, and the 6mm AR Turbo (40 deg shoulder). They fit just as well as the 6.5 G in the AR-15 size platform. It is a question of speed vs. bullet efficiency as to what you like. You like speed, go with the 6mm, You prefer a little more efficiency go with the 6.5. Added: When you get apples to apples with these, the 6.5 wins. Without maximizing the 6.5 (i.e. best B.C) the 6mm will usually win.

Which brings me to the .308 vs. 6.5G. The .308 flat out has more power and will wipe a 6/6.5's ass inside 600 yds. Outside 600 the .30 cal bullet is way less efficient than either the 6/6.5, so they will win past about that mark. The best shooter is the one who will really do it though. I will say, we had three shooters on my last 24" Grendel. We dialed the rifle up to hit @ 1k yds. Each of us put three hits on a 4 moa gong, center mass, within five seconds. For recoil control, the 6.5 (comped) is way easier to handle than the .308 (comped).

It's more about bullet efficiency than power. The 6.5 G will kill anything a .308 will....and then it will reach farther out with enough ability to kill.

Added:

Love the rifle Danco411!
 
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I'm a Grendel nut too. I'm on my second build. I'm running a 20" Satern 1:8 twist. Shoots the 123 Amax at 2450. By far my favorite rifle. Planning to hunt whitetail with it in Nov. I ran it out to 750 yards with no issues. Consistent hits on ISPC sized plates. Tan out of elevation so I had to get a 20 MOA mount. Now I figure I'm good out to 1k.

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I'm running the same optics setup you are..but I got the 30 MOA AD mount..how do you like that reticle???
 
I like the Vortex scopes. I ended up selling the 6-24 PST and am now running a 4-16 HS-T which is much better for hunting. I love the EBR reticles.

My build list

Spikes Enhanced Gen2 billet Ambi Lower
Hiperfire Competition Trigger (LOVE IT)
Luth-AR stock
JP silent captured spring
Cross Hill Tech ambi side charge upper
Satern 20" SS Match barrel
MI 15" SS Gen2 Keymod rail
3 port custom compensator
Rifle length gas with Seekins adjustable gas block
Viper 4-16 HS-T in AD Recon 20 MOA mount
Using AA Grendel Mags
 
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I like the Vortex scopes. I ended up selling the 6-24 PST and am now running a 4-16 HS-T which is much better for hunting. I love the EBR reticles.

My build list

Spikes Enhanced Gen2 billet Ambi Lower
Hiperfire Competition Trigger (LOVE IT)
Luth-AR stock
JP silent captured spring
Cross Hill Tech ambi side charge upper
Satern 20" SS Match barrel
MI 15" SS Gen2 Keymod rail
3 port custom compensator
Rifle length gas with Seekins adjustable gas block
Viper 4-16 HS-T in AD Recon 20 MOA mount
Using AA Grendel Mags


I'll have to hit you up soon, swap some ideas
 
Jealousy is unbecoming, but...

Nice set up...love the look, especially the ambidextrous charge from Cross Hill

My own humble offering in the Grendel...

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I like the Vortex scopes. I ended up selling the 6-24 PST and am now running a 4-16 HS-T which is much better for hunting. I love the EBR reticles.

My build list

Spikes Enhanced Gen2 billet Ambi Lower
Hiperfire Competition Trigger (LOVE IT)
Luth-AR stock
JP silent captured spring
Cross Hill Tech ambi side charge upper
Satern 20" SS Match barrel
MI 15" SS Gen2 Keymod rail
3 port custom compensator
Rifle length gas with Seekins adjustable gas block
Viper 4-16 HS-T in AD Recon 20 MOA mount
Using AA Grendel Mags
 
Sorry guys...life happens. Kids and driving to work. Now that I am at work, I can be on the internet hahaha!

Danco 411...sick rifle bro!

BC83...If I had to put a number on it I would like to stay under $2k but that's not a hard number. I will spend the money if the options are worth it to me. I am looking at either the Mark 6 3-18 or the March 3-24 for glass.
 
Sorry guys...life happens. Kids and driving to work. Now that I am at work, I can be on the internet hahaha!

Danco 411...sick rifle bro!

BC83...If I had to put a number on it I would like to stay under $2k but that's not a hard number. I will spend the money if the options are worth it to me. I am looking at either the Mark 6 3-18 or the March 3-24 for glass.

check out that Lilja barrel i found I think you will like it, also what upper receiver do you have?
 
Looking right now...
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the only problem i see is that it's a mid length gas system, and i agree with sandwarrior, rifle length is best..you could call lilja and see if they will cut their AR24 barrel down to 20". I've seen that barrel in action and it's a shooter! sold my JP that only that had 20rds down the pipe after seeing the groups that barrel will print..
 
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the only problem i see is that it's a mid length gas system, and i agree with sandwarrior, rifle length is best..you could call lilja and see if they will cut their AR24 barrel down to 20". I've seen that barrel in action and it's a shooter! sold my JP that only that had 20rds down the pipe after seeing the groups that barrel will print..

I was just typing that I was actually looking at a rifle length gas system on Sandwarrior suggested. I will have to get in contact with Lilja.
 
My lower and upper are just PSA blems. I am not opposed to using those for another build though if you guys have better suggestions.

While you'll probably be fine, I wouldn't chance it especially with the upper. If the face of the receiver isn't squared, the problems that can come from that will be amplified. A lot of great lighter weight billet uppers out there, that I'd suggest you go with.

The gas ports in the Lilja 18" barrels are sized specifically for an 18" barrel. I'm the one that ran the original group buy that got Lilja in the Grendel game. I'm the one who gave them the gas port sizes after getting the correct specs from the appropriate sources. (That group buy was an incredible learning experience for me.)

That being said, I always suggest adjustable gas blocks, particularly the SLR blocks.

On top of that, 18" do benefit from longer gas systems. However, an 18" with a rifle length gas system can be very finicky. Precision Firearms sells an 18" barrel with intermediate gas system, which will come with the appropriate gas tube.

I think you'll be very happy with either a PF or Lilja barrel.

IMHO an 18" Fluted barrel sounds like it would be perfect for you. I'd suggest a light weight 2.5-10x scope.

Here's my latest build.

PF Bartlein Barrel 16" Fluted, Spikes billet Upper forged Lower, NF 2.5-10x24 mil/mil in an ADM Recon mount.


I'm currently working on another group buy with Lilja, as I've got a serious itch for a Grendel SBR.
Grendel Short Barrel Group Buy Orders
 
U can save weight with a lightweight handguard. I really like the Midwest industries ss series, about 6 ozs lighter then alot of other handguards. I went with a 16 inch barrel but my compensator is 3 8 inches and 6 ozs, it's good made by wci, but I would love to use a shorter lighter one. I run a swfa ss 3-15 scope, and with bipod and monopod on a magpul ctr the rifle is right at 10 lbs, nice and handy for hunting and the factory hornady ammo slams deer hard in my experience with excellent accuracy for factory ammo. Selwayarmory.com seems to have the best prices and availability for factory grendel ammo. I luv the grendel and am building a 7.5 inch pistol as an experiment super lightweight rig. You also might consider the jp enterpises low mass bolt I believe that will save 6 ozs. For what you want any 16 to 20 inch barrel will be fine and I think the 18 inch barrel is the perfect length for the cartirdge. If I was considering a longer barreled grendel I would probably step up to the 6.5 creedmoor in an ar 10....
 
While you'll probably be fine, I wouldn't chance it especially with the upper. If the face of the receiver isn't squared, the problems that can come from that will be amplified. A lot of great lighter weight billet uppers out there, that I'd suggest you go with.

The gas ports in the Lilja 18" barrels are sized specifically for an 18" barrel. I'm the one that ran the original group buy that got Lilja in the Grendel game. I'm the one who gave them the gas port sizes after getting the correct specs from the appropriate sources. (That group buy was an incredible learning experience for me.)

That being said, I always suggest adjustable gas blocks, particularly the SLR blocks.

On top of that, 18" do benefit from longer gas systems. However, an 18" with a rifle length gas system can be very finicky. Precision Firearms sells an 18" barrel with intermediate gas system, which will come with the appropriate gas tube.

I think you'll be very happy with either a PF or Lilja barrel.

IMHO an 18" Fluted barrel sounds like it would be perfect for you. I'd suggest a light weight 2.5-10x scope.

Here's my latest build.

PF Bartlein Barrel 16" Fluted, Spikes billet Upper forged Lower, NF 2.5-10x24 mil/mil in an ADM Recon mount.


I'm currently working on another group buy with Lilja, as I've got a serious itch for a Grendel SBR.
Grendel Short Barrel Group Buy Orders

Nice lookin...dog! Ha! You have the Ace stock I am leaning towards!
 
U can save weight with a lightweight handguard. I really like the Midwest industries ss series, about 6 ozs lighter then alot of other handguards. I went with a 16 inch barrel but my compensator is 3 8 inches and 6 ozs, it's good made by wci, but I would love to use a shorter lighter one. I run a swfa ss 3-15 scope, and with bipod and monopod on a magpul ctr the rifle is right at 10 lbs, nice and handy for hunting and the factory hornady ammo slams deer hard in my experience with excellent accuracy for factory ammo. Selwayarmory.com seems to have the best prices and availability for factory grendel ammo. I luv the grendel and am building a 7.5 inch pistol as an experiment super lightweight rig. You also might consider the jp enterpises low mass bolt I believe that will save 6 ozs. For what you want any 16 to 20 inch barrel will be fine and I think the 18 inch barrel is the perfect length for the cartirdge. If I was considering a longer barreled grendel I would probably step up to the 6.5 creedmoor in an ar 10....

Looking at the AP Customs carbon fiber handguards...only around 6oz!
 
I put an Ace on a JP lower that I had, and I didn't like it at all. It felt like I was laying my face on a cheap piece of foam, which I was. I tried a friends Vltor, and now all of my ARs have them except my long range rig which has a PRS. I know the way stocks feel is a personal thing, but after using the Vltor, I don't understand why anyone would even consider the Ace.
 
I put an Ace on a JP lower that I had, and I didn't like it at all. It felt like I was laying my face on a cheap piece of foam, which I was. I tried a friends Vltor, and now all of my ARs have them except my long range rig which has a PRS. I know the way stocks feel is a personal thing, but after using the Vltor, I don't understand why anyone would even consider the Ace.

Good point on the foam. I like the looks of it though. I have a vltor on another ar15 and love it...it's just heavy and I'm looking for a lighter build.
 
So I just finished my friends Grendel build and he of course wanted Titanium Cerakote too. One of the major man rules is never have matching rifles so I had to redo mine. Hunting season is starting and I plan to hunt with my Grendel so I figured something more "natural" was in order. This is a blend of 40% OD Green, 40% Burnt Bronze and 20% Patriot Brown. The pics have a hard time showing the greenish tint but it's really cool. Whatchyall think?

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So I just finished my friends Grendel build and he of course wanted Titanium Cerakote too. One of the major man rules is never have matching rifles so I had to redo mine. Hunting season is starting and I plan to hunt with my Grendel so I figured something more "natural" was in order. This is a blend of 40% OD Green, 40% Burnt Bronze and 20% Patriot Brown. The pics have a hard time showing the greenish tint but it's really cool. Whatchyall think?

IMG_21081_zpsb0b40533.jpg


imagejpg9_zps320b2535.jpg


imagejpg8_zps1d4e6b32.jpg


imagejpg7_zpsc3bf6a91.jpg


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Those look awesome man! How long are the barrels and how do they shoot?
 
I dont see the point in the 6mm when you can run the 108 lapua scenars past 2800fps just fine.

If shooting paper the lighter and faster 6mm bullets will out perform the 6.5 bullets. That is why there has been a big surge in 6mm rifles in tactical shoots over the last 5 years. 6mmCM, 6x47, 6mm Creedmoor, 243.