Which AR round for whitetail deer?

[Tirod]

I don't believe anyone said the 6.8 was the same as the .308, just shot similar in trajectory. The 6.5 is, too.

A simple look at the ballistic tables with foot pounds of force and drop will show which fits the best. 7.62 X 39 is nothing more than a Russian copy of the .30-30. It drops yards at 300, 250 is about it's effective limit.

6.5 and 6.8 are much flatter shooters out to 400 yards. At that point the 6.8 begins losing it's edge in foot pounds of force due to the shorter bullet. The 6.5 maintains it's velocity and ft pounds out further, which is nice.

Either will do out to 250, so logistics becomes the decider. 6.8 has broad industry support, more makers involved with barrels, uppers, etc. White Oak, Bison, Noveske, almost two dozen will get you shooting for nearly any price range you want. Same for ammo. No, it's not a Fudd round in boxes at the 'Mart. Yet. Do you want to buy in volume from Silver State or Cabela's, you can, as with others. It's not a cheap plinker, but what is? Shoot .22 for that.

6.5 has been helped by Les Baer introducing the .246 LBC, which will feed and fire the same. He will have barrels and uppers, plus has ordered 700,000 cases to open up the bottleneck (stranglehold?) Alexander Arms was experiencing. Nonetheless, 6.8 has about 5 times the support and sources.

Whatever caliber you use, shoot a magazine designed for it. Magazines for 6.8, 6.5, and 7.62X39 exist, about in that order and availability. Cramming the wrong rounds into whatever just causes problems. They are different case diameters and shapes, the followers need to tilt the first round in at the proper angle, the feed lips are likewise different. If they were all the same, they would be.

For more info, go to 68forums.com where you will get data and sources on everything 6.8, including which rounds will shoot 3000 fps from a 16" barrel, something the other two calibers require a 20"+ barrel to do. That makes a difference on weight and handling when deer hunting. Having used a Win 94, Rem 700, and HK91, the AR in 6.8 is the best combination of them all.

 

[R.W.Dale]

A simple look at the ballistic tables with foot pounds of force and drop will show which fits the best. 7.62 X 39 is nothing more than a Russian copy of the .30-30. It drops yards at 300, 250 is about it's effective limit.

This is a MASSIVE over exaggeration, all of the rounds in question have the same thing in common they're all MID powered assault rifle cartridges and the all perform as such cartridges do. None of the rounds in question

A shoot particularly flat, none of these offer a MAX PBR much beyond 250yds NONE
or
B significantly outperform the others in this category

from a 200yd zero to 300yds
factory loads
6.5 Grendel-120grn Nosler B tip from AA-----------------9.9"
6.8SPC-110grn BanesDPX from CorBon------------------12.6"
7.62x39mm- 123grn Hornady V-max from DoubleTap-----13.9"
handloads
.30HRT-125 Sierra ProHunter by ME---------------------10.6"
7.62x39mm-125grn Nosler B-tip by me-------------------11.3

a REAL RIFLE cartridge for comparison
30-06-150grn Nosler B tip from Federal----------------7.2"

and that's just factory loads, keeping in mind the 6.X cartridges are new enough and loaded in such a way that the handloader cannot improve them much. 7.62x39 on the other hand can be transformed by a good hand load shooting the right bullet

 

[Kernel]

Did a OGW analysis of some possible AR-15 chamberings. The OGW method is a terminal ballistic performance indicator. It's one of the better, if not the best, formula based predictive tool. For a baseline I tossed in a .223 Rem. Looking at the graph above, the vertical axis is game weight in pounds. The horizontal axis is range in yards out to 500 yds. The six cartridge/bullet combinations I looked at were:

.223 Rem, 69 gr, at 3,000 fps.
.25 WSSM, 90 gr, 3,250 fps.
6.5 Grendel, 120 gr, 2,700 fps.
6.8 SPC, 115 gr, 2,630 fps.
7.62x39, 125 gr, 2,500 fps.
.30 Rem AR, 125 gr, 2,800 fps.

One of the most interesting findings is how close the 7.62x39 and the 6.8 SPC are. The model predicts near identical performance on game animals. The up shot to a potential buyer, if it comes down to a choice between the two, pick whatever is cheaper and easier - most likely the Russian. The difference between them would be indiscernible.

The .30 Rem AR has the highest OGW performance. Slightly better than factory .30-30. No surprise. It has the largest case and holds the most powder. It’s also “vaporware”, as someone mentioned, so take that into account. We also have to take Remington’s word on exterior ballistics, which may, or may not, prove out in the real world.

On paper the 6.5 Grendel is a hair better than the SPC and the Russian. Not enough to really make a difference. Perhaps some of this small advantage can be attributed to some very optimistic velocity figures that are being published for this cartridge. Maybe they are using some of that new "foo-foo" powder to put up these numbers. IMO, looking just at the case capacity and cartridge dimensions it shouldn’t be as fast as they say it is. My prediction is handloaders will not be able to duplicate factory muzzle velocities. The same could be said for the .30 Rem AR.

The .25 WSSM has high OGW performance and, by far, the best ballistic trajectory. This is the one to go with if you might be taking shots over 300 yds (which I‘d personally rarely, if ever, do). I didn’t bother to compare the trajectory numbers (wasn‘t really concerned with trajectory at this point - you can get that anywhere), but I can tell just by looking at it the point-blank-range for a 6-inch target is going to be around 275 yds.

Bottom line - the Grendel, Russian, SPC, and WSSM would all have about the same predicted performance on game animals. In other words, there’s not a dime’s difference between the four (from the standpoint of terminal performance). The .223 is significantly inferior, and the .30 Rem AR is slightly superior.

To me, the findings were kind of surprising. I thought there would be more differentiation. If I was looking for a AR-15 platform to hunt deer I’d likely go with a 7.62x39 because of the ease and lower cost to purchase, shoot, and handload. Knowing I’d give up nothing to the newer cartridges from the standpoint of effectiveness on game animals. With the exception of the .30 Rem AR which won’t be mainstream for at least a couple of more years, if ever.

Apologies in advance to all the High Roaders that get their panties in a bunch whenever someone speaks of mathematics or any attempt to apply science or logic to our sport. And to you guys, “Yes”, if the range is 1 yard further, and/or the deer 1 pound heavier, the bullet will just bounce off. :banghead:

 

[R.W.Dale]

I Must say Kernel that your well thought out and worded post not only Jives totally with mine and what I was trying to say but also blows it outta the water

 

[essayons21]

Krochus/Kernel,

What load data are you looking at for the 7.62x39? Are you using .308 or .310 bullets? My Hornady and Speer manuals show a .310 123gr bullet at 2500 as being a bit over max charge.

Are the AR 7.62x39 barrels .310" or .308" caliber?

 

[Lloyd Smale]

if the 762x39 is loaded to the same pressures as the 6.8 or the .30 rem it can do 2500 fps. Factory ammo isnt loaded to those pressure levels but theres sure no reason why it cant be. loaded to 50000 psi chamber pressure like the.30, .223 or 6.8 you can run a 125 to nearly 2600 fps. Im sure the powder makers are leary about some of the old worn out guns chambered for it. But in the ar platform its easily done. As a matter of fact i have loads for my ruger bolt gun (that im very careful to keep seperated from my ar ammo) that will do, Well lets just say a tad more then that

 

[MJR007]

Just wanted to say again, my 24" barrel AR15 25wssm (or maybe should call it Ar12.5) will push a 120 pill almost 3000fps without pushing pressure signs.

 

[R.W.Dale]

You can't load x39 for an AR quite as stout as you'd think. You push much beyond 2450 fps and you brass life will fall through the floor and you start to run into potental bolt breakage issues.

As to bbl & bullet dia. Any production x39 will have a .310" bore. HOWEVER this does not mean that the much better selection .308" bullets won't still shoot damn good.

For propellants there are TWO and only two you need to look at for 125g bullets. That's AA1680 or n120. If someone is telling you otherwize that person doesn't know what they're talking about.

 

[R.W.Dale]

We know you like your wssm

unfortunately if we wanted one we'd have to wait over a year to get it

 

[Kernel]

Essayon21,

You are very observant. I did give the Russian a small “boost“. My analysis above was based on a 24” barrel and what should be possible with a carefully developed handload. 2,500 fps is what my interior ballistics program says this cartridge is capable of. (Actually, if loaded to the same pressures as these other cartridges, IMO, it could probably even better that by a small margin).

Remington’s published velocities for the 7.62x39 is 2,365 fps for a 125 grain bullet. That’s laughably slow. Perhaps they’re concerned about some POS commie bloc SKS or AK coming apart at the seams. SAAMI spec on this cartridge is 45,000 psi. Which is not real high. But there’s no reason a handloader would have to download the 7.62x39 for use in an AR. You could safely approach the same pressure level as all these other cartridges.

I see in one of Krochus's other posts he was getting 2,400 fps with a 125 grain bullet in a 20” barrel. I’ll stand by my predicted 2,500 fps in a 24”. Even if I missed the mark by 25 or 50 fps it would hardly effect the OGW numbers at all. OGW is not hyper sensitive to velocity. One of the things I like about it.

MRJ007,

If that's true (.25 WSSM. 3,000 fps and 120 gr) then you would have performance very similar to the .30 Rem AR. Better, in fact. Identical at the muzzle, but slightly better as we go out to 500 yds due to the superior ballistic coefficient of .25 caliber bullets. My interior ballistics program say’s your numbers are in the range of possibilities, but, IMO, you are really pushing the pressure envelope. What’s your case life been like and what powder are you using? (Don’t need to know the charge wieght).

 

[MJR007]

I have been playing with H414 and H4350 in the 25wssm lately. My AR is rough on the shoulder of my cases. Case life has been around 6x. I am sure it would be better in a nonAR but the wssm makes no sense in any other rifle (to me). I find my rifle likes the mid 2900fps range best.

 

[R.W.Dale]

This appearently needs to be repeated

you CAN NOT load 7.62x39 to the same pressure as 223/6.5g/spc

the bolts are not strong enough to handle that much pressure on a .440" casehead unless you custom chamber one using a Grendel style bolt

 

[R.W.Dale]

http://www.c16/762/all.jpg

 

[Kernel]

H414 and H4350

Yep. Right in there is where I'd go. Maybe try some RL-19, too.

you CAN NOT load 7.62x39 to the same pressure as 223/6.5g/spc

Point taken. Kroke, why so many broken bolts? Slow learner? I think I'd change my underwear and stop at the first one.

 

[R.W.Dale]

On the ar a 7.62x39 bolt is thinned out as much as is practical for the platform due to the larger casehead. Now this isn't a problem unless you're either pushing the pressure envelope or shooting full auto like the bolts in the above pic

 

[Lloyd Smale]

Ill buy the bolt breakage as i know its been a problem in the ars but the brass life dosent fly. Ive loaded my ruger 77 up to 50000 psi chamber pressure and have brass thats on its 5th loading now and is still fine. I would think if you did it in something with very large cut chambers like some aks and skss the brass life would be a consern but a newer ar should be cut to spec. I have a question about the bolt breakage problem. Has anyone really determined the cause. Has anyone docmented a case that it was caused by running real high pressures? I would think just the oposite. A high pressure round causes the brass to grab the chamber walls and not come back against the bolt. that is why you get stuck cases with high pressures. I would think that if anything would pound on a bolt it would be low pressure rounds. Id just like to know if YOU have had this problem and it happened while shooting high pressure rounds or are you just passing on internet info. Ive heard of it happening with wolf ammo and my thoughts there are that the bottom line is wolf is crap ammo. I would have to guess theres just as much chance of gettting an occasional round that is underloaded as there is of getting a case that overloaded using it. In all my years of loading and ive probably done more of it then anyone here ive never seen a powder measure dump an overcharge. Ive seen them bridge over and though light ones many times though. I would think on wolfs machines the chance of an over charge would be about nil compared to an undercharge. My guess is these bolt are breaking because of bolt back thrust aginst the locking lugs not from the extractor getting overworked pulling out the cases. I would think in that case the extractors would be breaking. Bottom line is Kernels estimate of 2500 fps is still obtainable with the right powders ie 1680 or re7 at pressue levels around 44000 psi which is very little if anything over what some factory ammo is loaded to. If this level of ammo is going to break my bolt locking lugs then there going to break eventually anyway. Its just a matter of time. So who is suppose to make the best bolt for these things without a rechambering? Where do i get one?

 

[MetalHead]

Brass life in an autoloader is shorter than in a bolt gun.
First thing is if the ARs gas system is set for factory rounds it's way overgassed for hot hand loads, use a 16 inch barrel and carbine gas system and you are asking for trouble, run a mid-length or rifle length gas system. Check the play of your bolt between the barrel and barrel extension, I've heard High_Power shooters like .0015 to .003 clearance, a bolt with a lot pf slack will set the cases shoulder back and them hammer the lugs, this is all bad and sadly not easy to fix.
On the topic of bolt lugs, checking that all bear evenly is a good idea, some have polished the lug across from the extractor so it barely touches, this is supposed to reduce the load of the lugs on each side of the extractor. I have seen a bolt being sold by AR Proformance that looks good but have not seen any feedback on them, they have a radius where the lug transistions into the bolt face to spread the load, they even have a bolt and barrel extension for cases of .473 dia. it still will NOT LET YOU SHOOT 308 in a small frame AR, 308BR might work but I'd want something like 358BR! As is I plan on one for my DPMS upper and then sell my spare no-name bolt.
I also think these "cures" for extractor proablems don't help bolt life, first don't open the bolt till the preasure is down, longer gas systems and heaver bolts/bolt weights/heaver buffers.
Run a good sharp edged extractor and polish the ramp so the round slides in easier, run carbon silicon extractor springs, they deal with heat better and last longer.
Make sure the chamber has a good polish, this has been vital for good function of the AR from the first as it does not have a primary extraction cam to ease rounds out of the chamber.
Disclaimer: all this is my opinion.

 

[Dr. Tad Hussein Winslow]

krochus, please elaborate on what that picture teaches us.

And I change my vote to .25 WSSM - had forgotten about that one - definitely the best deer round from an AR.

 

[R.W.Dale]

Lloyd Smale

but the brass life dosent fly. Ive loaded my ruger 77 up to 50000 psi chamber pressure

Have you loaded for an AR15 chambered for 7.62x39mm? In this respect an auto loader differs GREATLY from your ruger.

I would think just the oposite. A high pressure round causes the brass to grab the chamber walls and not come back against the bolt. that is why you get stuck cases with high pressures.

You are missing the FUNDAMENTALS on bolt thrust completely, you can load 7.62x39 and .223 to the same pressure and the larger case head of x39 will put much more stress on the bolt. The tapered case on 7.62x39 only serves to exacerbate the increased pressure acting like a wedge on the bolt. Then to top it all off a 7.62x39 bolt has a lot of material relieved from the web between the lugs and breachface

This issue is well known in AR15 circles and is also why real AA 6.5Grenedl ar15 uppers use a completely different and much stronger bolt barrel extension from 7.62x39 even though the case heads are the same.

Am I saying a 7.62x39 AR15 is a piece of crap? NO But I am saying it's an ill suited platform for the velocitycentric handloader to use to turn 7.62x39 into a 300savage

Id just like to know if YOU have had this problem and it happened while shooting high pressure rounds or are you just passing on internet info.

NO because of my brass condition because it became obvious that that was time to stop adding powder at SAAMI max, who do you think I am Clark? I had another platform for thermonuclear pressure 7.62x39 loads
http://thehighroad.org/showthread.php?p=5111739#post5111739

My guess is these bolt are breaking because of bolt back thrust aginst the locking lugs not from the extractor getting overworked pulling out the cases.

really??? since the extractor is a thin piece of spring steel and the locking lugs are solid Carpenter No. 158® Steel

Bottom line is Kernels estimate of 2500 fps is still obtainable with the right powders ie 1680 or re7 at pressue levels around 44000 psi which is very little if anything over what some factory ammo is loaded to.

from a longer bbl say 24" yes (see above link) but that would be a completely custom order

So who is suppose to make the best bolt for these things without a rechambering? Where do i get one?

ARPerformance superbolt is supposed to be quite good as are a couple of the other bolts from the pic above
http://www.ar15performance.com/inc/sdetail/339

 

[R.W.Dale]

krochus, please elaborate on what that picture teaches us.

In a nutshell all the pic does is shows the non believers that a 7.62x39 bolt WILL NOT do things a .223 bolt will all week long. You put a lot of stress on a 7.62x39 bolt either with high pressure loads or short gas systems and it WILL break.

BUT this is all MOOT in my opinion as you don't have to resort to stupid pressures (cough SPC cough!) to get 7.62x39 to kill the snot out of bambi inside 300yds


more
http://thehighroad.org/showthread.php?p=2274479#post2274479
http://thehighroad.org/showthread.php?p=5111739#post5111739
http://thehighroad.org/showthread.php?t=362501&highlight=7.62x39

 

[Skylerbone]

Are all gun forums alike? These continuous rants about which round is perfect are agonizing. Forget about attacking someone else's cartrige of choice lest it become a nine page thread on who's dad can beat up who's (mine CAN take your's by the way) and lets give Essay what he's asking for. Its fine to point out problems with particular setups but speaking from experience trumps theory and internet bs any day.

Essay, I'd go .308...on a Remington 700 and skip the new upper as its even money. That being said, and said just so I could suggest .308 AGAIN which STILL WON'T WORK with your lower my money's on a 6.8spc for RELIABILITY. You've expressed your desire to take Virginia whitetail with the rifle at 250yds or less and it will. I would suggest you purchase new magazines for it, 5 round (laws can change back and fourth) and mark them distinctly.

It may also be of help to note your preference in upper; barrel length, flat top, has to have OD green furniture, etc. for suggestions on manufacturers who might offer the most compatible choice for you. Also, if you decide on a 6.8, point yourself over to Silver State Armory (avail. through MidwayUSA, etc.) and consider small base resizing dies to avoid feed problems. You won't get as lengthy a brass life but it can make the difference on whether you get a second shot or not.

On a final note which does apply a bit of science and math (which I support albeit from a laymen's perch) overpressuring is NEVER a good idea. SAMMI applies the math and science for you and stakes their reputation to it. Hot loads that exceed the maximum recommended for the sake of trajectory tell you one thing: you chose the wrong caliber and didn't bring enough gun. Those who ignore specs ought to google CVA Apollo failures to find out what happens when too much pressure is applied. (short version: if the barrel isn't spec'd to the owner's manual's recommended powder charge, fingers, hands and eyes will be lost!). Ok, just one more thing, since I'm soapboxing here, I'm glad the original poster is choosing to remain legal on his choice of caliber. Those who suggested he disregard State law ought to look into your own state's penalties. In Iowa, home of Tom "I'm too liberal for liberals" Harkin and same sex marriage, the DNR may and will take the animal harvested and any tools used in harvesting it. That means your deer, your rifle, the quad runner you hauled it out of the woods with and the truck you used to transport it with. Then there's the fine and the prison time if the rest of it doesn't deter you. Sure you can take down a deer with a .22 short to the head but if DNR says you can't, you'd best take their word on it.

 

[MTMilitiaman]

I can't speak for handloads, nor do I have any experience with the cartridge through an AR. But I can tell you from experience that Wolf ammo from an AK or an SKS is not dropping "yards" at 300 yards. A foot and a half with a 200 yard zero is more accurate. At that range, I aim for the head and have no problem scoring COM hits.

The 7.62x39 may not shoot as flat as some or even most of the cartridges being compared here, and that really shouldn't surprise anyone. Its been well known since its inception that the cartridge shoots a light-for-caliber bullet with a low SD and BC at a very modest velocity. But it still deserves to be considered an intermediate range cartridge and whether it is an AK with an Aimpoint or an SKS with TechSights, I consider the cartridge legitimate for at least 300 yards.

Also, keep in mind that most of these cartridges are going to lack effectiveness increasingly as range get beyond 300 yards. But the diameter and mass of the stubby Russian 7.62 comes in handy. At 300 yards, it gives you about 1500 fps and 700 fpe, even from most steel cased ammo producing muzzle velocities of 2300 to 2400 fps. That's from a .31 caliber ~125 gr bullet, which gives it the energy and momentum of a factory defensive .357 Magnum load. That is still fairly effective. And like I said, you're only dealing with 14 to 16 inches of drop with a 200 yard zero, at that range, even with crappy cheap Russian ammo and guns. I know this from experience, because it's not unusual for us to stretch our AKs out to 300 yards or more. Anyone who thinks the AK or the 7.62x39 is not solid to at least that range is hereby invited to take a walk downrange...

 

[GPWASR10]

+1 on the 7.62 x 39. I mean with Handloads and Soft point hunting rounds your basically talking about a Semi Auto, more accurate, Win Model '94 in .30-30, a round that is sononimous with whitetail hunting.

 

[essayons21]

Skylerbone,

I posted this thread to provoke (some) of those caliber rants. Through these, I have learned a ton about different caliber options for the AR15. I didn't even consider 7.62x39 initially because I only had experience with it in an SKS and AK, whose accuracy is far too poor for the application. I learned that this can be an accurate round in the AR platform, and as a reloader I can push it a bit more. The 6.5 and 6.8 are still good options, so there is really no wrong answer... kinda like I expected.

I already have half a dozen rifles that will take whitetail in my area, most of which more effectively than any AR15 chambering (including a few Rem700s). The point is, as Krochus' signatures says, I want to take my poor EBR hunting. I am also thru military service far more familiar with the AR platform than any other weapon, so it makes sense to take a gun that points naturally and I am quick and accurate with.

This is a discussion forum, and people will disagree and fight to the end over minute differences. To me, thats the point, and I learn from the disagreements. The "rants", as long as they are somewhat well reasoned, are a good thing.

Our VGDIF will do the same thing if you are found hunting or fishing illegally, basically taking everything but the clothes off your back. Strangely though, if you are a member of a native american tribe, you can legally take a deer with a .22 short.

 

[essayons21]

Krochus,

I read your thread re: .308 vs .310 bullets. Very interesting. What are you using for your hunting load?