Building an AR for Deer....

hal9000 · February 1, 2017, 06:44 PM

I've got an itch to build an AR 15 based light hunting rifle that can be loaded up for deer/antelope, and loaded down far enough for rabbit if I want. To me that means something in the .243-260/6-6.5mm range.

I know there are now a handful of chamberings based on Grendel and BR Brass. And I'm not familiar with any of them. I've found plenty of threads among paper punchers about accuracy, but that hardly seems like a good starting point for a hunting rifle.

I'm limiting myself to a 20-22" barrel length, relatively light contour barrel. And as much as I'd like to pretend that I'll be taking 1000 yard shots, 500 is a more realistic limit (and thats only if I manage to get drawn for Antelope, which doesn't happen often in AZ). And of course feeding/cycling is going to be an important factor.

Sooooo... Opinions? 6.5 Grendel? 6mmAR? 6mm or 6.5 BR? What's going to to best out of a short barrel? Feed out of an AR mag with some amount of consistency? Have a good variety of hunting bullets in a variety of weights? Deliver enough energy to take down a deer reliably? Etc...

Thanks all

MarkCO · February 1, 2017, 07:06 PM

The next one I want to try is the 6mmAR-Turbo Improved.

lockedcj7 · February 1, 2017, 09:08 PM

After doing a lot of research, I bought a 6.8 SPC for my son to deer hunt with. It is near MOA accurate and seems to be powerful enough out to at least 150 yds. I would not attempt a 500 yd shot on game with any AR chambering.

You can buy a special 6.8 SPC magazine but a standard 5.56 magazine will feed fine as long as it's not loaded to capacity. It uses standard .277 bullets like .270 win. so there are plenty of choices.

The downside is that it requires a specific bolt. You might as well buy a dedicated upper, and as cheap as lowers are, a complete rifle.

UncleEd · February 1, 2017, 09:34 PM

I was drawn to this thread because, frankly, I know nothing about ARs except they seem more expensive than a decent light wight bolt action rifle.

Seems like the good old bolt action rifle is just the ticket for deer, antelope hunting.

USCS · February 1, 2017, 10:40 PM

I've had good results with my 6.8 out to 200 yards.

kozak6 · February 2, 2017, 02:01 AM

6.5 Grendel is probably your best bet.

6.8 does better closer in, but 6.5 Grendel does better further out. Cheap practice ammo is also available.

FrankenMauser · February 2, 2017, 03:35 AM

My personal preference is for:

6.8 SPC
.25-45 Sharps
6x45mm

...In that order.

6.8 SPC is easier to live with, and has much more ammunition available.
.25-45 Sharps and 6x45mm are fairly expensive to deal with, if only buying factory ammo. And, even if reloading, have severe overall length limitations, which, in turn, limits bullet selection significantly.

But if I wanted a deer/antelope-specific AR, I'd be stepping up to .308-class ARs, rather than dealing with the 'little' AR-15.

MarkCO · February 2, 2017, 08:29 AM

Quote:

Seems like the good old bolt action rifle is just the ticket for deer, antelope hunting.

I would agree with you. Cheaper, lighter, more accurate in general. But it is fun to hunt with an AR once in a while.

Iwanttoshootbettter · February 2, 2017, 10:09 AM

What USCS said that 6.8 kicked all 6 of uses butts 2 weeks ago on a MLD hunt he was shooting head shots at 100-130 yards choosing nostrils ears eyes for very clean ethical shots this caliber has My attention

DubC-Hicks · February 2, 2017, 01:58 PM

6.5 Grendel seems to be catching on very well right now. People have been taking it to 1000yds on paper with pretty good success. I've seen a white tail doe taken at 275 yards with it and the Hornady SST. Easy 5 foot tracking job. And very impressive damage.

When I build a hunting/long range AR, it'll be in the Grendel.

michaeldarnold · February 2, 2017, 02:47 PM

If you're a handloader, there is another AR caliber in development. 7mm Valkyrie. I'm interested in this caliber as I already hand load for my 7mm Rem Mag.

It's all proof of concept right now but testing is positive.

Check this page out for more info.
http://www.7mmvalkyrie.com/about.html
I don't have anything invested in this yet other than research time but it looks really cool.

Mike in STL.

surveyor · February 2, 2017, 03:27 PM

The next one I'm thinking about is a 6 mm fat rat or 6 mm ar turbo improved.

Mainly on common 6.5 grendel brass, bolts and mags.

It will be awhile, still in research stage.

Mobuck · February 2, 2017, 09:59 PM

Grandson has killed 4 deer with 4 shots using a 6x45mm 20" barrel AR. It does work although it seems to have bullet performance issues I have yet to solve. I wouldn't recommend it for ranges over 200 yards.
I used a 6.8 this year and found it to be well suited for deer at 150-200 yards.

I'm giving serious thought to 6mm or 257 on either a 6.8 or 22 Nosler case. Even that won't be a 500 yard medium game round.

tahunua001 · February 2, 2017, 11:19 PM

I have a 20 inch 6.5 grendel build. it's my favorite deer rifle of all time, but it's in no way light. I heavily recommend it, but be warned that if you walk long distances, it'll really be weighing you down by the end of the day.

CarJunkieLS1 · February 3, 2017, 03:21 AM

Are you a handloader? If you are then I'd definitely be looking st the 7mm Valkyrie mentioned earlier in this thread. The caliber is the KING for deer/ antelope, hogs, etc. inside the AR-15 platform. It was mentioned that the caliber is in development thats not completely accurate as there are more than 50 rifles in the wild that are up and running. I've used my Valkyrie the last 2 deer seasons and results have been stellar.

The Valkyrie beats the Grendel in every ballistic there is from the muzzle to as far as anyone can care to shoot. If you reload choose the Valkyrie if going to the store for ammo is important go with the Grendel.

jmr40 · February 3, 2017, 07:24 AM

One chambered in 223 will do everything you want to do with a lot less drama. You can show where some of the other rounds look somewhat better on paper, but at the end of the day a 223 loaded with good 65-75 gr bullets kills deer just as well at 200-300 yards.

If you want more punch you need to go up to the AR-10 platform and start shooting 308, or 308 based rounds such as 243 or 260. Or better yet buy a bolt rifle.

Mobuck · February 3, 2017, 08:15 AM

"6.8 does better closer in, but 6.5 Grendel does better further out."

Comparing 6.5 Grendel velocities to "real long range cartridges" will give you some thought provoking information. By the time you get into a "long range" bullet weight, the Grendel's MV is too low to give you much real world range.

In my book, there's a BIG difference between walking bullets onto a static target with the only goal of making a hole in that target and making a solid first round hit at an unknown range with enough authority to call it a hunting round.

hal9000 · February 3, 2017, 11:44 PM

Hey guys, thanks for all the feedback: Regarding these two little tidbits....

"But if I wanted a deer/antelope-specific AR, I'd be stepping up to .308-class ARs, rather than dealing with the 'little' AR-15. "

"Seems like the good old bolt action rifle is just the ticket for deer, antelope hunting. "

... What I DIDN'T say was that my motivation here is to use up a spare set of AR15 receivers that have been sitting around for a few years. My "normal" deer rifle is my 25-06 bolt gun. This is just a fun project. But I still need to be able to tell myself that it's a useful tool.

I'd previously been leaning heavily towards the 6.8 SPC, but now I'm leaning away from trying to push anything bigger than .260 cal out of an AR15. As a few people have pointed out, I think that's getting into AR-10 territory, and the smaller cal bullets that are more suited to the -15 should be more than adequate for deer/antelope. I might make an exception for the 6.8 SPC.

If I were building on an AR-10 platform the 7mm -08 would probably be my top choice. I haven't heard of the 7 Valkyrie, what case is is based on and what kind of MV's are you getting with them?

And yes, I do reload. Don't even mind forming my own brass if that's what it takes (NOT that I'm going for a wildcat round... I'm just not limited that way)

michaeldarnold · February 4, 2017, 12:33 AM

It is based on the 6.5x47 Lapua case with the shoulder pushed back to allow it to run in the ar15 at-2.295 oal-and necked up to 7mm.

Sent from my HTC 10 using Tapatalk

CarJunkieLS1 · February 4, 2017, 03:38 AM

Hal9000 if you use google and search 7mm Valkyrie you'll find the information you are looking for. The velocities that you'll see is real world velocities from actual users. My personal Valkyrie 20" barrel pushes a 120 Nosler Ballistic Tip to 2782fps and its not a max load or using the optimum powder for velocity. With a 140 I could get 2700-2750 but I haven't used them very much.

jetinteriorguy · February 4, 2017, 08:22 AM

How about good old 7.62x39 in the AR platform. Years ago when the Mini 30 first came out I grabbed one for deer hunting. This was back in North Dakota with pretty large northern deer. I had no problem taking deer out to 250 yards, never had one run over 50 yards, usually less than 10 if they didn't drop in their tracks. Don't have the Mini anymore but just built a 7.62x39 with a Stoner upper on an AeroPrecision lower and it shoots MOA no problem, about half the size of my old Mini at just sub 2MOA. Fast becoming a favorite of mine.

stagpanther · February 4, 2017, 08:53 AM

I have faced this same "dilemma" for years and have arrived at my own conclusions--just my opinions.

1) Basically, you are going to be forced to stay within performance limits of case capacities for either 5.56 or grendel/6.8 spc flavors (and are widely available and supported with SAAMI specs) or you are going to push the boat out in pursuit of exotic wildcats which increase the case capacity limits but are not "time tested" and will necessarily involve committing to wildcat limitations--which include, but are not limited to, hard to find brass/ammo, lack of load testing data, unknown long-term stability/reliability issues in an AR15 platform etc.

2) IMO, if you want to remain relatively conservative (a good idea when the moment of decision arrives in either a hunting or SD situation) I would limit my choices to the 5.56/gredel/6.8spc world of calibers.

3) I've spent considerable time on various ballistics programs, and while they don't tell the full story of how a cartridge will ultimately perform, I've found that most of the time the most effective performance combination regardless of the bullet/caliber choice between 5.56/grendel/6.8spc (and their wildcat dirivitaves necked up or down) usually ends up in the neighborhood of 2400 to 2600 fps with a muzzle energy maxed out in the range 1400 ftlbs +/-. IMO, this is a good formula for most any of the AR15 derivatives when used inside of 200 yds. There is only one notable exception to this that I have found in my playing around with QL data--and that's when driving a 130 gr 6.5 grendel cartridge through a 20" or better barrel--under those circumstances that cartridge is a clear winner in retaining energy out well past 200 yards over all the other common derivatives IMO.

I've built several 6.8 spc and grendel/264 lbc carbines, and while the performance perameters of the newer wildcats are very attractive in an AR carbine type weapon for hunting, I've decided my next build is going to be a grendel with a "top-shelf" 20" barrel because of brass and ammo limitations of the more exotic choices.

Just my armchair opinion--not intending to insult anyone's "cartridge de jour."

ed308 · February 4, 2017, 11:00 AM

Ok...., we need add 270AR to the mix for the wildcat options. .277 (or 6.8) .277 bullets up to 130 gr or even 140 grs sitting on top of a necked up 6.5x47 Lupua case. 130 gr bullets at 2700-2800 fps is sweetness. The 270AR and 7mm Valkyrie are probably the most powerful AR15 cartridges currently available for the AR15 frame. Both have similar performance and range. And both will smoke the Grendel. Hopefully one of them becomes SAAMI approved at some point. (If forming the brass for either of these wildcats turns you off, Bruce Finnegan (developer of the 7mm Valkyrie) will form it for you. And you'll get 10 shots out of it if you don't load hot.)

AR15 Performance has 270AR barrels, bolts and dies in stock:

http://www.ar15performance.com/inc/sdetail/38016/36220

Of course I'm also partial to the 6.8. If you like hunting and carrying a short barreled AR, 6.8 is the way to go. If lugging a long barreled AR around is your thing, then 6.5 Grendel is probably a better choice. Both will work and would be a good choice. I went the AR10 route initially for hunting but quickly dumped it for the 6.8. I'm too lazy to carry weight while hunting. For the bench it's fine. But my preference is a light weight 16" barrel when I hunt. That's where the 6.8 SPC II shines.

MarkCO · February 4, 2017, 11:08 AM

If you want power, look at the .450Bushmaster or .458 SOCOM.

My .450Corvette (.450BM modified to allow higher pressures) pushes 300 grain slugs at 2500 fps and prints 4" 300 yard groups.

hal9000 · February 4, 2017, 07:09 PM

Thanks again guys.

Regarding the .308 based cartridges (Valkyrie, 6.5x47 and BR variants), how much of a problem will breakage be? As I recall, once upon a time, AR-15's had breakage problems when chambered in the smaller 6.5grendel, and case diameter was consistently called out as the culprit. Have those issues been resolved, or will parts breakage still be an occasional problem with any of these rounds?

In all honesty, I have at least 6-8 weeks before I even think about starting my build. It won't happen until I finish my masters thesis (which I should be working on as we speak!), and have a little bit of free time. Hopefully I'll know what I want by then.

On a related note, what do you all think about wood furniture for the AR? To me it seems more appropriate than the normal milspec stuff for a hunting rifle.

February 1, 2017, 06:44 PM	#1
hal9000 Member Join Date: October 15, 2010 Location: AZ Posts: 82	Building an AR for Deer.... I've got an itch to build an AR 15 based light hunting rifle that can be loaded up for deer/antelope, and loaded down far enough for rabbit if I want. To me that means something in the .243-260/6-6.5mm range. I know there are now a handful of chamberings based on Grendel and BR Brass. And I'm not familiar with any of them. I've found plenty of threads among paper punchers about accuracy, but that hardly seems like a good starting point for a hunting rifle. I'm limiting myself to a 20-22" barrel length, relatively light contour barrel. And as much as I'd like to pretend that I'll be taking 1000 yard shots, 500 is a more realistic limit (and thats only if I manage to get drawn for Antelope, which doesn't happen often in AZ). And of course feeding/cycling is going to be an important factor. Sooooo... Opinions? 6.5 Grendel? 6mmAR? 6mm or 6.5 BR? What's going to to best out of a short barrel? Feed out of an AR mag with some amount of consistency? Have a good variety of hunting bullets in a variety of weights? Deliver enough energy to take down a deer reliably? Etc... Thanks all

February 1, 2017, 07:06 PM	#2
MarkCO Senior Member Join Date: October 21, 1998 Location: Colorado, USA Posts: 4,308	The next one I want to try is the 6mmAR-Turbo Improved. __________________ Good Shooting, MarkCO www.CarbonArms.us

February 1, 2017, 09:08 PM	#3
lockedcj7 Senior Member Join Date: February 15, 2007 Posts: 1,215	After doing a lot of research, I bought a 6.8 SPC for my son to deer hunt with. It is near MOA accurate and seems to be powerful enough out to at least 150 yds. I would not attempt a 500 yd shot on game with any AR chambering. You can buy a special 6.8 SPC magazine but a standard 5.56 magazine will feed fine as long as it's not loaded to capacity. It uses standard .277 bullets like .270 win. so there are plenty of choices. The downside is that it requires a specific bolt. You might as well buy a dedicated upper, and as cheap as lowers are, a complete rifle. __________________ To a much greater extent than most mechanical devices, firearms are terribly unforgiving of any overconfidence, complacency or negligence. Last edited by lockedcj7; February 1, 2017 at 10:18 PM.

February 2, 2017, 03:35 AM	#7
FrankenMauser Senior Member Join Date: August 25, 2008 Location: In the valley above the plain Posts: 13,427	My personal preference is for: 6.8 SPC .25-45 Sharps 6x45mm ...In that order. 6.8 SPC is easier to live with, and has much more ammunition available. .25-45 Sharps and 6x45mm are fairly expensive to deal with, if only buying factory ammo. And, even if reloading, have severe overall length limitations, which, in turn, limits bullet selection significantly. But if I wanted a deer/antelope-specific AR, I'd be stepping up to .308-class ARs, rather than dealing with the 'little' AR-15. __________________ Don't even try it. It's even worse than the internet would lead you to believe.

February 2, 2017, 01:58 PM	#10
DubC-Hicks Senior Member Join Date: December 20, 2009 Location: Backwoods, Northern MI Posts: 1,031	6.5 Grendel seems to be catching on very well right now. People have been taking it to 1000yds on paper with pretty good success. I've seen a white tail doe taken at 275 yards with it and the Hornady SST. Easy 5 foot tracking job. And very impressive damage. When I build a hunting/long range AR, it'll be in the Grendel. __________________ ”Gun control is like trying to reduce drunk driving by making it tougher for sober people to own cars.” ~Unknown

February 1, 2017, 09:34 PM	#4
UncleEd Senior Member Join Date: April 13, 2013 Location: N. Georgia Posts: 1,150	I was drawn to this thread because, frankly, I know nothing about ARs except they seem more expensive than a decent light wight bolt action rifle. Seems like the good old bolt action rifle is just the ticket for deer, antelope hunting.

February 1, 2017, 10:40 PM	#5
USCS Senior Member Join Date: September 9, 2009 Location: South Carolina Posts: 114	I've had good results with my 6.8 out to 200 yards.

February 2, 2017, 02:01 AM	#6
kozak6 Senior Member Join Date: June 16, 2005 Location: AZ Posts: 3,113	6.5 Grendel is probably your best bet. 6.8 does better closer in, but 6.5 Grendel does better further out. Cheap practice ammo is also available.

February 2, 2017, 10:09 AM	#9
Iwanttoshootbettter Member Join Date: November 16, 2016 Location: Laporte Texas Posts: 79	What USCS said that 6.8 kicked all 6 of uses butts 2 weeks ago on a MLD hunt he was shooting head shots at 100-130 yards choosing nostrils ears eyes for very clean ethical shots this caliber has My attention

February 2, 2017, 02:47 PM	#11
michaeldarnold Senior Member Join Date: April 8, 2016 Location: St. Louis Suburbs Posts: 137	If you're a handloader, there is another AR caliber in development. 7mm Valkyrie. I'm interested in this caliber as I already hand load for my 7mm Rem Mag. It's all proof of concept right now but testing is positive. Check this page out for more info. http://www.7mmvalkyrie.com/about.html I don't have anything invested in this yet other than research time but it looks really cool. Mike in STL.

February 2, 2017, 03:27 PM	#12
surveyor Senior Member Join Date: April 13, 2007 Posts: 770	The next one I'm thinking about is a 6 mm fat rat or 6 mm ar turbo improved. Mainly on common 6.5 grendel brass, bolts and mags. It will be awhile, still in research stage.

February 2, 2017, 09:59 PM	#13
Mobuck Junior member Join Date: February 2, 2010 Posts: 6,846	Grandson has killed 4 deer with 4 shots using a 6x45mm 20" barrel AR. It does work although it seems to have bullet performance issues I have yet to solve. I wouldn't recommend it for ranges over 200 yards. I used a 6.8 this year and found it to be well suited for deer at 150-200 yards. I'm giving serious thought to 6mm or 257 on either a 6.8 or 22 Nosler case. Even that won't be a 500 yard medium game round.

February 2, 2017, 11:19 PM	#14
tahunua001 Senior Member Join Date: July 21, 2011 Location: Idaho Posts: 7,839	I have a 20 inch 6.5 grendel build. it's my favorite deer rifle of all time, but it's in no way light. I heavily recommend it, but be warned that if you walk long distances, it'll really be weighing you down by the end of the day. __________________ ignore my complete lack of capitalization. I still have no problem correcting your grammar. I never said half the stuff people said I did-Albert Einstein You can't believe everything you read on the internet-Benjamin Franklin

February 3, 2017, 03:21 AM	#15
CarJunkieLS1 Senior Member Join Date: October 1, 2013 Posts: 686	Are you a handloader? If you are then I'd definitely be looking st the 7mm Valkyrie mentioned earlier in this thread. The caliber is the KING for deer/ antelope, hogs, etc. inside the AR-15 platform. It was mentioned that the caliber is in development thats not completely accurate as there are more than 50 rifles in the wild that are up and running. I've used my Valkyrie the last 2 deer seasons and results have been stellar. The Valkyrie beats the Grendel in every ballistic there is from the muzzle to as far as anyone can care to shoot. If you reload choose the Valkyrie if going to the store for ammo is important go with the Grendel.

February 3, 2017, 07:24 AM	#16
jmr40 Senior Member Join Date: June 15, 2008 Location: Georgia Posts: 10,810	One chambered in 223 will do everything you want to do with a lot less drama. You can show where some of the other rounds look somewhat better on paper, but at the end of the day a 223 loaded with good 65-75 gr bullets kills deer just as well at 200-300 yards. If you want more punch you need to go up to the AR-10 platform and start shooting 308, or 308 based rounds such as 243 or 260. Or better yet buy a bolt rifle. __________________ "If you're still doing things the same way you were doing them 10 years ago, you're doing it wrong" Winston Churchill

February 3, 2017, 08:15 AM	#17
Mobuck Junior member Join Date: February 2, 2010 Posts: 6,846	"6.8 does better closer in, but 6.5 Grendel does better further out." Comparing 6.5 Grendel velocities to "real long range cartridges" will give you some thought provoking information. By the time you get into a "long range" bullet weight, the Grendel's MV is too low to give you much real world range. In my book, there's a BIG difference between walking bullets onto a static target with the only goal of making a hole in that target and making a solid first round hit at an unknown range with enough authority to call it a hunting round.

February 3, 2017, 11:44 PM	#18
hal9000 Member Join Date: October 15, 2010 Location: AZ Posts: 82	Hey guys, thanks for all the feedback: Regarding these two little tidbits.... "But if I wanted a deer/antelope-specific AR, I'd be stepping up to .308-class ARs, rather than dealing with the 'little' AR-15. " "Seems like the good old bolt action rifle is just the ticket for deer, antelope hunting. " ... What I DIDN'T say was that my motivation here is to use up a spare set of AR15 receivers that have been sitting around for a few years. My "normal" deer rifle is my 25-06 bolt gun. This is just a fun project. But I still need to be able to tell myself that it's a useful tool. I'd previously been leaning heavily towards the 6.8 SPC, but now I'm leaning away from trying to push anything bigger than .260 cal out of an AR15. As a few people have pointed out, I think that's getting into AR-10 territory, and the smaller cal bullets that are more suited to the -15 should be more than adequate for deer/antelope. I might make an exception for the 6.8 SPC. If I were building on an AR-10 platform the 7mm -08 would probably be my top choice. I haven't heard of the 7 Valkyrie, what case is is based on and what kind of MV's are you getting with them? And yes, I do reload. Don't even mind forming my own brass if that's what it takes (NOT that I'm going for a wildcat round... I'm just not limited that way)

February 4, 2017, 12:33 AM	#19
michaeldarnold Senior Member Join Date: April 8, 2016 Location: St. Louis Suburbs Posts: 137	It is based on the 6.5x47 Lapua case with the shoulder pushed back to allow it to run in the ar15 at-2.295 oal-and necked up to 7mm. Sent from my HTC 10 using Tapatalk

February 4, 2017, 03:38 AM	#20
CarJunkieLS1 Senior Member Join Date: October 1, 2013 Posts: 686	Hal9000 if you use google and search 7mm Valkyrie you'll find the information you are looking for. The velocities that you'll see is real world velocities from actual users. My personal Valkyrie 20" barrel pushes a 120 Nosler Ballistic Tip to 2782fps and its not a max load or using the optimum powder for velocity. With a 140 I could get 2700-2750 but I haven't used them very much.

February 4, 2017, 08:22 AM	#21
jetinteriorguy Senior Member Join Date: April 28, 2013 Posts: 3,182	How about good old 7.62x39 in the AR platform. Years ago when the Mini 30 first came out I grabbed one for deer hunting. This was back in North Dakota with pretty large northern deer. I had no problem taking deer out to 250 yards, never had one run over 50 yards, usually less than 10 if they didn't drop in their tracks. Don't have the Mini anymore but just built a 7.62x39 with a Stoner upper on an AeroPrecision lower and it shoots MOA no problem, about half the size of my old Mini at just sub 2MOA. Fast becoming a favorite of mine.

February 4, 2017, 08:53 AM	#22
stagpanther Senior Member Join Date: March 2, 2014 Posts: 11,801	I have faced this same "dilemma" for years and have arrived at my own conclusions--just my opinions. 1) Basically, you are going to be forced to stay within performance limits of case capacities for either 5.56 or grendel/6.8 spc flavors (and are widely available and supported with SAAMI specs) or you are going to push the boat out in pursuit of exotic wildcats which increase the case capacity limits but are not "time tested" and will necessarily involve committing to wildcat limitations--which include, but are not limited to, hard to find brass/ammo, lack of load testing data, unknown long-term stability/reliability issues in an AR15 platform etc. 2) IMO, if you want to remain relatively conservative (a good idea when the moment of decision arrives in either a hunting or SD situation) I would limit my choices to the 5.56/gredel/6.8spc world of calibers. 3) I've spent considerable time on various ballistics programs, and while they don't tell the full story of how a cartridge will ultimately perform, I've found that most of the time the most effective performance combination regardless of the bullet/caliber choice between 5.56/grendel/6.8spc (and their wildcat dirivitaves necked up or down) usually ends up in the neighborhood of 2400 to 2600 fps with a muzzle energy maxed out in the range 1400 ftlbs +/-. IMO, this is a good formula for most any of the AR15 derivatives when used inside of 200 yds. There is only one notable exception to this that I have found in my playing around with QL data--and that's when driving a 130 gr 6.5 grendel cartridge through a 20" or better barrel--under those circumstances that cartridge is a clear winner in retaining energy out well past 200 yards over all the other *common* derivatives IMO. I've built several 6.8 spc and grendel/264 lbc carbines, and while the performance perameters of the newer wildcats are very attractive in an AR carbine type weapon for hunting, I've decided my next build is going to be a grendel with a "top-shelf" 20" barrel because of brass and ammo limitations of the more exotic choices. Just my armchair opinion--not intending to insult anyone's "cartridge de jour." __________________ "Everyone speaks gun."--Robert O'Neill *I am NOT an expert--I do not have any formal experience or certification in firearms use or testing; use any information I post at your own risk!*

February 4, 2017, 11:00 AM	#23
ed308 Senior Member Join Date: November 5, 2016 Location: DFW, TX Posts: 1,147	Ok...., we need add 270AR to the mix for the wildcat options. .277 (or 6.8) .277 bullets up to 130 gr or even 140 grs sitting on top of a necked up 6.5x47 Lupua case. 130 gr bullets at 2700-2800 fps is sweetness. The 270AR and 7mm Valkyrie are probably the most powerful AR15 cartridges currently available for the AR15 frame. Both have similar performance and range. And both will smoke the Grendel. Hopefully one of them becomes SAAMI approved at some point. (If forming the brass for either of these wildcats turns you off, Bruce Finnegan (developer of the 7mm Valkyrie) will form it for you. And you'll get 10 shots out of it if you don't load hot.) AR15 Performance has 270AR barrels, bolts and dies in stock: http://www.ar15performance.com/inc/sdetail/38016/36220 Of course I'm also partial to the 6.8. If you like hunting and carrying a short barreled AR, 6.8 is the way to go. If lugging a long barreled AR around is your thing, then 6.5 Grendel is probably a better choice. Both will work and would be a good choice. I went the AR10 route initially for hunting but quickly dumped it for the 6.8. I'm too lazy to carry weight while hunting. For the bench it's fine. But my preference is a light weight 16" barrel when I hunt. That's where the 6.8 SPC II shines. Last edited by ed308; February 4, 2017 at 11:09 AM.

February 4, 2017, 11:08 AM	#24
MarkCO Senior Member Join Date: October 21, 1998 Location: Colorado, USA Posts: 4,308	If you want power, look at the .450Bushmaster or .458 SOCOM. My .450Corvette (.450BM modified to allow higher pressures) pushes 300 grain slugs at 2500 fps and prints 4" 300 yard groups. __________________ Good Shooting, MarkCO www.CarbonArms.us

February 4, 2017, 07:09 PM	#25
hal9000 Member Join Date: October 15, 2010 Location: AZ Posts: 82	Thanks again guys. Regarding the .308 based cartridges (Valkyrie, 6.5x47 and BR variants), how much of a problem will breakage be? As I recall, once upon a time, AR-15's had breakage problems when chambered in the smaller 6.5grendel, and case diameter was consistently called out as the culprit. Have those issues been resolved, or will parts breakage still be an occasional problem with any of these rounds? In all honesty, I have at least 6-8 weeks before I even think about starting my build. It won't happen until I finish my masters thesis (which I should be working on as we speak!), and have a little bit of free time. Hopefully I'll know what I want by then. On a related note, what do you all think about wood furniture for the AR? To me it seems more appropriate than the normal milspec stuff for a hunting rifle.