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jason41987
July 12, 2012, 01:41 PM
hey everyone.. im building an AR15 soon, and well, ill be investing in a couple different uppers for it.. one of these uppers id like to make would be for big game hunting, so id be looking for accuracy, range, and of course a cartridge better suited for the task.. so im thinking 18-20 inch barrel, free floating forearm, maybe invest in a good trigger group as well...

so any suggestions for individual components i should look into, and advice for a good large game cartridge that could fit in an AR-15 mag?... maybe 6.8 SPC, 6.5 grenel, 30 remington AR, 300 AAC blackout to name a few ive thought of

Wyosmith
July 12, 2012, 02:04 PM
How big is your big game?
If you have elk, moose or big bears on the list you'll want to look at a 458 SOCOM or a 50 Beowulf.

If you are going for deer, I'd recommend a 6.8SPC over about any of them.

If you are hunting mostly Pronghorn antelope I might give a nod to a 6.5 Grendal.

I have killed a lot of antelope and deer both with my 6.8 SPC and I find its ok out to about 400 yds, and has been excellent to 300 The Grendal is a bit better past 300 yds, but neither is going to kill super well past 400.

The bullets that fly so well in the grendal don’t perform well on game as a rule. So I am toild by my friends that hunt with them anyway.

The 458 and the 50 are both in the league of the old Sharps rounds, so they have LOTS of power --- but don't shoot flat.

If you must have a lot of power and a lot of range both the AR-15 is not the correct rifle. Look at the browning BARs in the bigger chamberings if you need a 400-500 yard elk rifle in an automatic.

jason41987
July 12, 2012, 02:12 PM
300 yards would be about the max limit for what i need.. what size bullets does the grendel use? the 6.8 uses standard 7mm bullets doesnt it?.. since id be reloading often, id want something that uses a common, easy to find bullet

tobnpr
July 12, 2012, 02:52 PM
For big game, short yardage, it's the .50 Beowulf or the .450 Bushmaster or .458 Socom from the AR platform.

The .300 has decent power with supersonic loads at short distances, but I wouldn't call it "big game".

The 6.5 Grendel (we own one) is unsurpassed for long range ballistics-target shooting- from the AR-15 platform, but not the best choice for your application.

Like the previous posted asked- what's "big game" to you...?

jason41987
July 12, 2012, 03:11 PM
well, deer for the most part.. maybe the occassional elk on trips, but mostly just white tail

10-96
July 12, 2012, 04:03 PM
the 6.8 uses standard 7mm bullets doesnt it?.. No, those are .270's in the 6.8 ctg.

RT
July 12, 2012, 04:22 PM
I'd go Grendel at longer ranges and 300 Blackout for inside 200 yards
http://www.ar15.com/forums/t_1_5/1326642_is_there_any_real_advantage_to_300blk__KILL_PICS_POSTED.html

Barnes 110 gr Vortex FTW
http://www.youtube.com/watch?v=9mXa5AiT0r4

jason41987
July 12, 2012, 06:11 PM
im reading up more right now on the 6.5mm grendel vs the 6.8mm SPC since these seem to be the front runners in more power and range in the AR15 platform, and the nature of the the 6.5mm grendel with even a slightly smaller diameter bullet is capable of carrying bullets of equal weight but with what seems to be about .100 more in ballistics coefficiency... hard to find a 6.5mm bullet that doesnt have over .500

really seems like it might be turning into a 6.8 vs 6.5 debate for me.. and i think i might have a bit more fun with this upper with some long range target shooting as well as hunting.. seems the 6.5 is the better cartridge ballistically but the 6.8 has a bigger market and more support.. tough choice, ill have to do more research on these

tobnpr
July 12, 2012, 07:19 PM
The 6.8 SPC is wholly inferior for long range shooting.

Alexander Arms has a couple of 6.5 Grendel factory loads for hunting, but you really need to handload until commercial ammo catches up as this caliber is rapidly getting the respect it deserves since SAAMI acceptance.

If you handload, want whitetail, and the best long range ballistics available from the AR-15 platform, the 6.5 Grendel is the clear choice.

http://www.rifleshootermag.com/2011/11/02/6-5-grendel-evolution/

jason41987
July 12, 2012, 07:46 PM
hmm, what size barrel length would the 6.5 grendel be best in?..

im thinking i could build a long range rifle with a heavy, or fluted barrel, free float forearm, quality bipod, stock with adjustable cheek comb, match trigger group and good optics

im also guessing for an absolute sharpshooter, im thinking direct impingement will be better.. i dont think a short-stroke piston would offer me any advantage, actually, i could be wrong, but i think it might decrease the accuracy vs DI

riggins_83
July 12, 2012, 08:50 PM
In my home state it's illegal to use anything under a 24 caliber 70 grain for Deer, 85 grain for big game. I'd go AR10 platform if you want something for larger game.

jason41987
July 12, 2012, 10:05 PM
i would be willing to get behind one of these new cartridges.. the 6.8SPC seems to be more suited as a general purpose role as an alternative to the 5.56.. grendel seems to be better suited as a long range target/sniper role.. its impressive to see either one putting out close to 2,000 ft/lbs of energy

what i can gather load wise is that both these cartridge have the same case capacity, grendel being a shorter, fatter case, spc being a but longer but skinner, which also restricts the length of the bullet

seems the max bullet lengths in an AR is about 140 grains in the grendel, about 130 in the spc.. can anyone confirm longer bullets can be used in either cartridge in the AR15?...

given both cartridges are fatter than the 5.56, im just curious how much ammo a standard 30-round size magazine would hold?.. i think teh grendel has to be single-stack?

jason41987
July 12, 2012, 10:14 PM
looking at load data for these two cartridges they put out the same amount of energy.. either one plenty for taking big game... so about these two cartridges itself, lets say you have one 6.8spc and one 6.5 grendel, equal amounts of kinetic energy, same type of bullet.. and for the sake of arguement, lets say the same bullet weight as well... how much of an energy difference would you guess there would be out to 1000 yards?

Sinlessorrow
July 13, 2012, 08:26 AM
I say 5.56, stick to 50gr barnes black hills TSX and 70gr TSX and trust me youll have no problems.

Nothing hitting a deer with a bullet that expands to .50 cal dimensions within 1" of tissue and twirls with 4 tearing petals of pure copper.

Another thing to note is 70gr TSX expands fully out to 300yrds out of a 14.5" M4

madcratebuilder
July 13, 2012, 08:55 AM
hmm, what size barrel length would the 6.5 grendel be best in?..

The local Grendel shooters I shoot with have everything from 16" up to 24". The short barrel guys have proven the 16" doesn't give up much at all. For a "hunting" Grendel 16-18" would be fine. Game is taken at much shorter ranges, 200-300yds max, the 6.8 or the 6.5 both do very well at these ranges. The Grendel shines past 600yds and well keep shining past 1200yds. In the AR15 platform the Grendel is the best for long range shooting. For hunting some of the larger .40cal+ rounds may do better.

If you think you may be hunting Elk then you should consider one of the 7.62 platform AR's. The 7.62/.308 allows much more flexibility for hunting big game.

jason41987
July 13, 2012, 01:10 PM
ive done some ballistics number crunching... finding the maximum length bullets for both 6.5 and 6.8 in the AR15 platform, and finding the average ballistics coefficiency for bullets offered in these sizes, increasing the velocity of each round to achieve the same amount of muzzle energy of 1900ft/lbs, both zeroed at 100, grendels using a 140 grain bullet with a BC of .520, grendel uses a 130 grain bullet with a BC of .460.. for the sake of eliminating variables, i used a hornady interlock SST boat tail bullet for each

what ive discovered is at 600 yards, grendel had 793ft/lbs energy and a drop of 118.5" - spc had 710 ft/lbs of energy and 115" drop

at 800 yards grendel had 584ft/lbs of energy and -249" of drop - spc had 503 ft/lbs of energy and 247" of drop

at 1000 yards grendel had 442 ft/lbs of energy and -455" of drop, spc had 374 ft/lbs of energy and and -458" of drop

so... to recap, i eliminated many unneccessary variables using the same bullets, the same kinetic energy at the muzzle, both cases have the same case capacity, and the only variables i left are those of the ballistic coefficiencies of the bullets, and the overall bullet weight (obviously, longer bullets give better coefficiencies in the same diameter and construction)

with all possible variables eliminated, only keeping the two variables that make these cartridges ballistically different, SPC has an edge out to 600, theyre about even at 800, and the grendel edges out at 1000, and none of these ranges are realistic for anything besides extreme-range target shooting, but even then i dont see enough of a different to base a decision on either of these on their individual ballistics, and i cant imagine the minute difference in kinetic energy

so i think im going to go for one which is going to have the largest support and backing by aftermarket and other shooters which at this point seems to strongly favor the 6.8SPC

jason41987
July 13, 2012, 01:19 PM
so i think this build will end up being a 20 or 22 inch heavy barrel, free float tube, bipod mounted to the tube, adjustable stock for comfort, larger grip for comfort (large hands) if anyone can confirm theres no accuracy loss with the short-stroke piston conversions, i would go that route, if not, it would remain direct impinged.. and i dont want to go with a hair trigger of 1 1/2 pounds, i think thats too light to remain practical for more than bench rest shooting, so im looking at a quality trigger with about a 3lb pull to it

could anyone recommend a good barrel, a trigger, and probably a good scope as well?... im thinking between a 6 and 8 times scope for hunting... something durable, rugged, and can take a bit of a beating, something thats can handle a little abuse?

tobnpr
July 13, 2012, 04:37 PM
I don't understand your methodology...

You determine the maximum velocity (on average) you can push the bullet based on it's weight- and the energy is whatever it is...

You say you "increased the muzzle velocity" to obtain a certain level of energy? That's not how load development is done....

I'll bet a case of beer of your choice that, whatever bullet you're using for the 6.8 SPC, your velocity is unrealistic- or flat out unobtainable.

Please state the specific bullets you're using, the muzzle velocity of each and the load you're basing it on...

I suspect you'll see the 6.8 SPC cannot compare to the 6.5 Grendel at 1000 yards if you use realistic bullet weights and obtainable velocities.

The bullet of choice for most Grendel shooters is the 123 Amax, pushed at about 2350 fps.

What bullet, and what velocity are you estimating for the 6.8?

The 6.8 can hang with the 6.5 Grendel only to about 500 yards- then the higher BC, 6.5 bullets walk away.

I have never heard of anyone building a 6.8 SPC with 1000 yard shooting in mind.

jason41987
July 13, 2012, 04:58 PM
both cartridges fire projectiles at similar weights, and have the same cartridge capacity, so muzzle energy isnt going to be very different, ive looked into some numbers from handloads fired from the AR15 platform and only fine-tuned the velocities to match the muzzle energy to eliminate just another variable that didnt need to be in there... also, since the loads used were on the upper end of the pressure limits i also tested a 120 grain 6.5 bullet against a 110 grain 6.8 bullet, and i was only testing bullets that i can find a manufacture that makes the bullet in both sizes at the bullet weights im testing

so.. for the 120 vs 110 grain test i used the ballistic coefficiencies in the barnes tipped triple-shock X spitzer boat tail bullets...

to answer the question above i used around 2,560fps for the 6.8 in both bullet sizes, so the more standard pressure tests put the 6.5 and 6.8 at 1600ft/lbs of energy, which is more common

the results of this test were roughly the same, though a tad more pronounced, the 6.8 had a SLIGHT edge at 600, about even at 800 and the grendel pulled ahead after that, but not by much

tobnpr
July 13, 2012, 05:40 PM
The Barnes TSX, 6.8 mm, 110 grain has a BC of .323

The Hornady Amax, 6.5 mm, 123 grain has a BC of .510

At 2560 fps, the Barnes has a drop of 135 inches at 600 yards, and 627 inches at 1000...

At 2350 fps, the Hornady Amax has a drop of 128 inches at 600, and 508 at 1000.

So, despite the lower MV and heavier bullet, the 6.5 is moving away at 600.

The 6.8 SPC goes subsonic (1129 fps) beyond 700 yards- which makes it pretty much useless- with that bullet at least, beyond that range. At 1000, it has only 922 fps and 208 lbs. of energy.

The 6.5 Grendel is still humming at 1117 fps at 1000, with 341 ft. lbs.

I'm not going to argue the point further, your ballistic calcs. are incorrect.

There is no way on earth the 6.8 SPC can carry 374 lbs of energy at 1000 yards as you maintain.

jason41987
July 13, 2012, 05:51 PM
tobnpr, the barnes TSX boat tail hollow point has a BC of .323, the spitzer boat tail with the plastic tip has a BC of .377, both are 110 grains though.. and i didnt use the a-max in the comparison because i wanted to eliminate bullet type and construction as a variable, and couldnt find an a-max for the 6.8, which is what i was trying to find first before using a barnes, and none of these cartridges are ballistically fantastic after 800 yards, even if i was the type to take these extremely long range shots at a deer, which i dont, and usually hunt sub 200 yard ranges, i seriously doubt the 100ft/lbs difference at beyond 100 yards is going to do much with bullets made to expand at much higher velocities

i love the a-max bullets, ive been a user of hornady bullets for a while and the a-max are very efficient in long range ballistics, unfortunately without them making a 110 grain 6.8mm a-max bullet it just wouldnt have been a fair comparison

TMD
July 13, 2012, 06:06 PM
You say your thinking of a 22" heavy barrel for a hunting rifle.... Yeah, your gonna enjoy carrying that in the woods all day.

jason41987
July 13, 2012, 06:51 PM
i was actually thinking more of a 20, and im used to carrying my 28" 12 gauge around all day

MLeake
July 13, 2012, 07:21 PM
Shotgun barrels have a lot less steel per inch of length than do centerfire rifle bull barrels.

jason41987
July 13, 2012, 08:03 PM
yeah, thats true, but the overall weight was still roughly the same as such an AR15 would be, and ive carried heavier things than either of them and it doesnt concern me much... when i hunt i have a few places i go to, and do more waiting than traveling on foot, so even if i had a 24 inch heavy barrel it still wont weigh as much as other rifles ive carried before

Stargazer
July 13, 2012, 10:21 PM
https://dl.dropbox.com/u/10728824/GunStuff/458SOCOM/size_matters_1639.jpg

The bottom caliber almost made the Buffalo extinct. That's pretty big game. :)

jason41987
July 14, 2012, 12:37 AM
i like that photo.. its almost artistic.. however, for the game we have around here that would be overkill... but if i ever run into bison ill give it a try

Baylorattorney
July 14, 2012, 04:18 AM
For elk I'd say 308 minimum. I take s tex white tail all season with 5.56.

jason41987
July 14, 2012, 04:29 AM
well, where i live there is no elk, i was thinking maybe future hunting trips, but eeh.. not so important, ive decided to go with the 6.8SPC though.. offers me a great middle ground between the 5.56 and .308 and seems to really be taking off in the aftermarket, out of all the other AR15 caliber conversions... also, it seems like i wont find myself in a situation where i cant find ammo in almost any gun shop

Acc371
July 14, 2012, 06:47 PM
The 6.8 SPC is wholly inferior for long range shooting.

Alexander Arms has a couple of 6.5 Grendel factory loads for hunting, but you really need to handload until commercial ammo catches up as this caliber is rapidly getting the respect it deserves since SAAMI acceptance.

If you handload, want whitetail, and the best long range ballistics available from the AR-15 platform, the 6.5 Grendel is the clear choice.

http://www.rifleshootermag.com/2011/...del-evolution/

We're catching up fast!
http://www.ssarmory.com/6.8_spc_ammo_140gr_VLD_Berger.aspx
Not too shabby for a 16" pipe. Where the 6.8's sweet spot is.
So, 'wholly', I wouldn't say that.
Yes, it is SPC II (or equivalent) ammo only.
I see barrel length hasn't been mentioned in in all the stats mentioned up to now..... Very curious??
6.8 is usually measured with a 16" barrel.

Jason, your only going to gain about 25-35fps per inch of barrel length past 16" in a 6.8. With no change in accuracy.
FWIW- My 18" SPR barrel is about 2.4lbs with a muzzle devise.
Also, like you eluded to, I can shop around at LGSs & find 6.8 ammo. I haven't found any Grendel ammo yet.

One good thing about both. Both have(& are capable) taken larger than deer big game! So, in the end - It just a matter of a person's preference & parameters.:)

jason41987
July 14, 2012, 07:19 PM
well i wouldnt neccessarily say its not going to do well with longer barrels... a 6.8mm sniper round might have a slower powder to make better use of longer barrels and deliver more velocity than a 20-30fps increase per inch, but for the most part i dont think factory ammo would gain much

why is it 6.5mm grendel users get so angry when you say something negative about it, but 6.8 SPC users dont seem to? ive been getting a lot of hate mail from the grendel users in saying theres too little difference to base a cartridge decision solely on 800+ yard ballistics and its true, and 99.99999% of the time only youre going to use 800+ yard ballistics if youre bench rest shooting anyway, and if that was my intent id be building a custom bolt action, not an AR15, the hate mail i seem to be getting for not thinking 6.5 grendel is useful enough to ignore the almost complete lack in after market vs 6.8 isnt going to help the case any

Acc371
July 14, 2012, 08:44 PM
well i wouldn't necessarily say its not going to do well with longer barrels... a 6.8mm sniper round might have a slower powder to make better use of longer barrels and deliver more velocity than a 20-30fps increase per inch, but for the most part i dont think factory ammo would gain much

Why is it 6.5mm Grendel users get so angry when you say something negative about it, but 6.8 SPC users don't seem to? I've been getting a lot of hate mail from the Grendel users in saying there's too little difference to base a cartridge decision solely on 800+ yard ballistics and its true, and 99.99999% of the time only you're going to use 800+ yard ballistics if you're bench rest shooting anyway, and if that was my intent id be building a custom bolt action, not an AR15, the hate mail i seem to be getting for not thinking 6.5 Grendel is useful enough to ignore the almost complete lack in after market vs 6.8 isn't going to help the case any.
Well, It's a similar case with Mathews bows. Everybody has to compare themselves to it. How many shooters out there take 800yard shots regularly? Yeah, there are places out west. But, the .308 has longer bullet expansion range than both.
True about the 6.8 after market. With Federal & Tula coming on board next year (Winchester & PMC looking closely) it will expand more.

I don't know why they would be sending that mail. Except, maybe buyer's regret?

PS Float Pilot has some number on 6.8 & a 24" BHW barrel & AA2200 powder.

http://www.blackholeweaponry.proboards.com/index.cgi?board=68speccaliber&action=display&thread=861

jason41987
July 14, 2012, 08:49 PM
buyers regret eh?.. probably why im not so quick to jump on new cartridges or new rifle designs, i like to wait and see if the aftermarket and manufacturer support takes off first and for all the wrinkles to be ironed out before i buy in.. seems like the 6.8 has already done all that

Acc371
July 14, 2012, 09:13 PM
I don't jump on too many bandwagons out of the gate either & like to see how things pan out too

I was jumped on for that about suggesting to a guy with A kid on the way to hold off on the 300 BO until the dust settled. Fortunately, the guy's comeback wasn't that good. Was easy to counter.
Just trying to help a guy out w/o bashing & another jumps my case. I know how you feel.
But, I don't really know why. I can only guess.

jason41987
July 14, 2012, 09:34 PM
well i hear a lot of people jumping on the .300 AAC blackout bandwagon as well, ballistically im not very impressed, its going to have a very low BC, and low velocity as well so i dont see a purpose for it outside of suppressed fire, which of course i dont see too many civilians getting into enough for it to really take off in my opinion

i just think for the action size we have to work with, there just isnt enough length to get a good BC in a 30-caliber round without seriously reducing the case capacity and losing the velocity needed to make it effective for more than suppressed operation

gun nut
July 15, 2012, 11:22 PM
I've got a 6.8 with a leupold. I'm very satisfied with it. Mine is 16" with 6 position stock. Great for getting around in the brush.

Milsurplover
July 16, 2012, 07:53 PM
Have you guys seen the new SSA 6.8 load with the 140gr Berger VLD? It requires a PRI mag that can hold 2.300 coal rounds to feed from the mag, but they have a ballistic table for it that shows it supersonic at 1000 yards from a 16 inch barrel. VERY impressive imo.

Edit: Sorry, didn't see the above link :D next time I will read more thoroughly before posting, my apologies!

jephthai
July 16, 2012, 08:45 PM
I can't tell if you've already bought your rifle yet, but I had a thought for you on barrel length. 22" is unheard-of long in the 6.8SPCII world. I have a 20", and that's considered on the fringe. The efficiency of the cartridge means that a 16-18" barrel is plenty, and the improvement for longer is quite marginal.

You said earlier that you expect your shots to be no more than 300 yards -- if so, you might really consider the 18" 6.8SPCII.

Why is it 6.5mm Grendel users get so angry when you say something negative about it, but 6.8 SPC users don't seem to?

I hear you -- I noticed the same when I was on the fence. I wanted the Grendel for the high BCs. But when I started to read the hunting stories, it seemed like the 6.8SPCII would be a better choice for me, since I do want to use mine for both range and woods duty. I still believe the Grendel has great advantages... it's just that no single caliber is "best" for everything.

Sometimes I wish there was a little more fairness in some of the debates you see around. Most Grendels are 20" barrels or more, and they do get benefit out of the length. Most 6.8s are 18" or less -- there's a lot of apples and oranges going on.

jason41987
July 16, 2012, 08:56 PM
ive already seem some hand loads using 130 grain bullets that were capable of similar performance than that, and the bullet these hand loads used were in my opinion, much better to hunt with, i really like the plastic tipped hunting bullets they have out now

anyway.. im going to go with a 16" carbine first, build something for more long range later on.. but i think ill focus for now on a 16" build first...

been doing more reading on the different chamber ratings, and barrel options and i think ill give one of the 16" ARP chamber barrels with nitro carburized finish a try in 6.8mm... and i usually hunt inside 200 yards, so i could wait on optics as well.. maybe get a 4x or 6x at some point when i need more range.. but... but itll definitely be a 6.8mm SPC rifle with a 16 inch barrel for my new hunting rifle

jason41987
July 16, 2012, 09:04 PM
no, i havent purchased my rifle yet.. since im usually a sub 200 yard hunter im just going to build an AR15 with a 16 inch barrel, and build a 20" upper later on for target shooting... but for an outdoor rifle i think a light weight 16" model would be best

jephthai
July 16, 2012, 09:22 PM
Cool, sounds like you're thinking it through and have a plan.

Sent from my DROID4 using Tapatalk 2

jason41987
July 16, 2012, 09:41 PM
yeah.. id really like to do something special with this though.. make it different than all others out there.. so ive been looking at some accessories i can use, such as side charging modifications, monolithic uppers, etc...

jephthai
July 16, 2012, 09:52 PM
I have a buddy who did the monolithic upper. Very nice equipment. In my 600yd prone matches, I've occasionally wished for the side charger, due to scope position wrt the charge handle.

Sent from my DROID4 using Tapatalk 2

jason41987
July 17, 2012, 07:05 AM
problem with the charging handle where it is, and a rifle you want to eventually use for longer ranges is you cant put a cheek rest there, it would block the charging handle.. and im not entirely sure what the purpose of a monolithic upper is... is it just appearance? or the full length rail on top? because ive seen stocks that offered full top rails without it

jason41987
July 17, 2012, 09:19 AM
i guess at this point this thread could be closed, since i did decide on a 16" 6.8SPC rifle ill build from parts, and will get around to start a thread relating to that later on when i need more assistance on that aspect