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Old February 9, 2020, 12:23 PM   #1
Jacket67
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Deciding on an AR10 caliber..

I've recently gotten the itch to put together an AR10. I have an AR15 and have been wanting to get a semiauto in a heavier caliber more suited for some hunting and the occasional long range shooting. Like many others have done, I am currently debating between going with .308 or 6.5 creedmoor.

I know many on here may jump to .308 for hunting larger game, but I currently have a 30-06 bolt action that I would use for things like elk and other large animals when not archery hunting. I also have a 30-30 for things like whitetail in more compact environments where a higher-power caliber may not be ideal.

Given this, I am stuck on the decision of adding another .30cal rifle to my repertoire (I don't reload just FYI), or adding in 6.5 creedmoor which I view as falling somewhere between my 5.56 and 30-06 that could be used for hunting and also be fun at the range.

I have read that 6.5 creed is more expensive than .308, but much of that information was dated a few years ago and I haven't seen many updates on a price comparison. Budgeting is always a factor for me, so any info on current cost comparisons would be very helpful.

Given my situation and intentions for this rifle, what recommendations do you have?

Thanks in advance.
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Old February 9, 2020, 01:45 PM   #2
T. O'Heir
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Judging strictly by available ammo on Midway, there are far more options with .308. Midway lists 71 flavours of the Creed. 152 in .308. Prices aren't a great deal different.
The only other criteria is that .308 ammo is everywhere. The Creed, probably, is not in smaller places. One of the guys coined the term, 'The Walmart Test'. If the ammo is in your local Wally World, it'll very likely be in all of 'em.
If you shoot much you will be reloading sooner or later. Reloading lets you tailor the ammo to your rifle and is more about the quality of the ammo than saving money. Same bullets for .30-06 and .308. Both love 165 grain hunting bullets. And both will kill any game in North America with a 165.
Oh and a .30-30 is just as, "long legged" as a .30-06. Dangerous out to several miles. Shotguns are for whitetail in "more compact environments". Your bow is the best for that though.
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Old February 11, 2020, 02:16 PM   #3
raimius
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You could do either, although for target practice, 6.5 will have less drop and be affected by wind a bit less.

Quote:
30-30 is just as, "long legged" as a .30-06.
. Physics would disagree.
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Old February 11, 2020, 03:33 PM   #4
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Weight is the primary determinant--if you really are going to use it for hunting--you're going to have a tough time building a "budget" AR 10 that's also light in weight unless you go something like a carbine, which by nature starts cutting into the cartridge's performance.
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Old February 12, 2020, 04:33 PM   #5
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I suggest the 6.5CM... it truly is that much better in my eyes.

Hunting wise, the 6.5x55 ( basically the ballistic twin of the 6.5CM ) has taken a LOT of critters.. frankly, I think it didn't catch on mostly from the lack of readily available surplus ammo after WWII.

The 6.5CM cheat's the wind very well... and is a great balance cartridge from a Large Frame AR.

To be blunt, I think you will find the 6.5CM very satisfying. Mine have shown very good precision.

The best part is... "if" you end up not liking the 6.5CM, a DIY to .308 barrel swap is super easy.

Or another complete upper will fit right on.

The only holdup I see... is the readily available 308 ammo... surplus 308 is still out there, and some of it is crazy accurate as well, typical priced at around 50 cents a shot.

On a good day... inexpensive 6.5CM ammo is cheapest at around 55cents / rd.. but that blunt nosed S&B 140gr FMJ bullet, while very accurate, is not taking advantage of the BC's of pointier 6.5 bullets... and is "slow" enough to limit it to 100-200 yds range time.

The next closest inexpensive factory round is Horn. AG 140gr... at around 70-80 cents per round... precision is VERY good from my 6.5CM barrels , and its BC is pretty darned good. ( I love this ammo )

Hunting bullets abound for both the 6.5CM and .308.. find one that is precise from your barrel you'll probably be GTG.

The 308 is proven as no slouch.. but, for me the 6.5CM is just enough better, that it is the caliber I reach for in my Large Frame AR's.

And, I gotta say... the satisfaction I get, from my consistently small groups with the 6.5CM pretty much overrides any added cost, ammo wise.
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Old February 12, 2020, 04:57 PM   #6
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I have, and have hunted with several different .308 pattern ARs. My current is a Daniel Defense, and they are pricey. When they offer a 6.5 barrel as a part, I will buy one and switch if over. My .308s are largely for subsonics and shooting Heavy or Mil in competition, but I'd not suggest it for a 3rd or 4th rifle...only maybe when you get to the 30th or so.

The 6.5CM is a little less versatile, but it makes up for it in the long range area. Also, I doubt I ever use a .308 pattern AR, in any caliber, to hunt with again. Heavy is the main reason. I do however hunt with my 6mm and 6.5mm AR15 pattern rifles.

6.5CM over .308 every day of the week except Sundays when I am feeling like a Boomer.
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Old February 12, 2020, 07:01 PM   #7
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I built my AR10 in .308 simply because I wanted an 18” barrel and I think the creedmore round needs a bit more tube to live up to its potential. Also, where I live .308 ammo is a good bit cheaper.
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Old February 12, 2020, 07:50 PM   #8
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One of my favorite AR10 builds--because it's just all around super reliable and not fussy about ammo and would be murder on game if I had just made in lighter--is a 358 win. This cartridge is undeservedly ignored IMO.
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Old February 12, 2020, 09:22 PM   #9
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An AR 10 in any cartridge is going to be a lot more rifle than I like to carry around while hunting. You will have a hard time keeping it under 10 lbs scoped. For hunting I'd much prefer a trim lightweight accurate bolt gun that weighs 6-7 lbs scoped.

The difference between 6.5 and 308 has been beat to death. I primarily hunted with 30-06 from the 1970's until about 10 years ago. For game smaller than elk it is simply bigger than needed. I chose 308 at the time because it could be used in lighter, trimmer rifles and still do 95% of what a 30-06 would do. And even in lighter rifles recoil was still manageable.

I own 6.5 rifles, but my go-to hunting rifles are still 308. Not that I think 308 is better, but I have money invested in rifles that I like and time invested in developing loads that work in them. At this stage of my life I'm probably not going to start over with another cartridge. The 308 does what I need it to do. The 6.5 is a range toy for me, I still prefer the 308 rifles for hunting because I just like those rifles better.

That said, the 6.5 is the better cartridge and what I'd recommend for someone starting. As a hunting cartridge out to 400 ish yards there isn't enough difference to matter. In fact on paper it can be argued the 308 is a touch better. But not enough to be a game changer. No animal will ever know the difference.

But at longer ranges, especially for punching paper or ringing steel the 6.5 starts pulling away. And most shooters today are punching paper more than hunting.

Ammo is no longer an issue. Yea, 308 offers more options, but you only need 2. Find a hunting load and a target load and what else do you need. Prices are about the same, in fact 6.5 will be a tiny bit cheaper for quality target loads. You can buy 6.5 ammo everywhere now including Walmart.

I handload my ammo but my brother and his son-in-law don't. They buy this locally for $13/box and have shot it sub MOA out to 600 yards. I can get a little more accuracy, but I can't hand load it for this price.

https://www.midwayusa.com/product/1020605499?pid=865833
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Old February 13, 2020, 08:19 AM   #10
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I love my 6.5 Creedmore build, it is currently my favorite rifle. I recommend using a JP BCG or at least their extractor and spring. It eliminated 100% of the minor functioning problems I initially had.
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Old February 13, 2020, 09:04 PM   #11
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6.5 creedmoor recoils less, so I read anyway, but if your "long range" isn't exceeding 500 yards then .308 will put more power to the target without any downside - aside from recoil, which is only an issue after a number of punishing shots and not a handful..

Generally speaking most people I see shooting will never see a benefit to 6.5 creedmoor, they are not stretching the range out enough for it to make a difference or running enough rounds where the recoil becomes punishing.
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Old February 15, 2020, 08:54 AM   #12
Areoflyer09
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For target use:

6.5 has noticeably less recoil than 308 in both semi-auto and bolt action forms. I’d take 6.5 all day, everyday over 308. 6.5 also has less drop and is less effected by wind at pretty much every distance last 100 yds. The only advantage the 308 has is cheaper plinking rounds, but the quality stuff isn’t that different in cost than 308.

Since you have other calibers you use to hunt, I would suggest taking a look at the 6mm Creedmoor as well. I like 308 and 6.5, I like the 6CM even more. For target use it can do pretty much everything the 6.5 can, but it does it with less recoil.

There is a reason the Creedmoors are popular with competition shooters. The 308 is still a solid choice, it just can’t fight drop and drift like the Creedmoors. And it does it all with more recoil.
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Old February 15, 2020, 10:10 AM   #13
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Hey Stagpanther.
I am going to build a 358 upper for an AR and maybe a 338 Federal. In the past I have used metal mags for customers, but I was thinking of using the Mag pull 10 round mag and I am going to use a scallop file to slim down the inner ribs about .040" per side to give better clearance to the case necks where they brace up against the shoulders of the cartridges.
Have you done the same?

In either the 338 or the 358 I believe very good ballistics can be achieved in a shorter barrel because of the room we have to burn powder. My customer wants a 16" and I see no real reason to argue for anything longer. In the 338 Fed I may stick with a 20" or go to an 18"

So my 2nd question for you is in your builds what barrel lengths did you used and did you do any chronographing of the loads?

Please let me know.

AR10 type rifles are not all that popular here in Wyoming and I have suggested the 358 to several people in the past because we have a lot of elk and grizzly bears, but for whatever reason the 2 calibers have not caught on with the auto shooters as much as I would have expected.

I make my own barrels and for a while I made my own handguards and gas tubes because I have found the issue with reliability that was an issue with the 308s and all smaller calibers was more related to port location than most other factors. In the 338s and the 358s it was not a problem because the powder has more room to burn. So I have used standard length tubes and standard barrel dimensions on my 338s and 358s so far, but I have not done the short carbine length on them yet, so this is an area I'd love to talk over with those that have.

Anyway, if you would not mind "talking shop" a bit, please get in touch with me
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Old February 23, 2020, 07:36 PM   #14
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I own bolt action rifles in .308 and 6.5cm and have regularly shot them out to 1000 yards. I also own AR10's in .308 and 6.5cm. As other posters have already stated, if you are punching paper/shooting steel there's not a whole lot of difference out to approx. 400 yards. Beyond that, the 6.5 cm will be significantly less affected by the wind and does not drop as fast. Also, recoils less - which is helpful if you don't have a spotter and are trying to see your misses.

However, if this is your first AR10, I'd go with .308 (unless you plan to do a lot of shooting out beyond 4-500 yards). Ammo is cheaper, particularly if you're going to be doing plinking/shooting steel at 1-300 yards and can use cheap mil surplus ammo. You will also have more choices in gun selection - especially if you have any interest in buying used. Finally, the barrel life on a .308 gun is way better than 6.5cm which is an advantage shooting semi-auto where it can be really easy to put 100+ rounds downrange before you know it.
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Old February 23, 2020, 09:05 PM   #15
stagpanther
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Quote:
Hey Stagpanther.
I am going to build a 358 upper for an AR and maybe a 338 Federal. In the past I have used metal mags for customers, but I was thinking of using the Mag pull 10 round mag and I am going to use a scallop file to slim down the inner ribs about .040" per side to give better clearance to the case necks where they brace up against the shoulders of the cartridges.
Have you done the same?

In either the 338 or the 358 I believe very good ballistics can be achieved in a shorter barrel because of the room we have to burn powder. My customer wants a 16" and I see no real reason to argue for anything longer. In the 338 Fed I may stick with a 20" or go to an 18"

So my 2nd question for you is in your builds what barrel lengths did you used and did you do any chronographing of the loads?

Please let me know.

AR10 type rifles are not all that popular here in Wyoming and I have suggested the 358 to several people in the past because we have a lot of elk and grizzly bears, but for whatever reason the 2 calibers have not caught on with the auto shooters as much as I would have expected.

I make my own barrels and for a while I made my own handguards and gas tubes because I have found the issue with reliability that was an issue with the 308s and all smaller calibers was more related to port location than most other factors. In the 338s and the 358s it was not a problem because the powder has more room to burn. So I have used standard length tubes and standard barrel dimensions on my 338s and 358s so far, but I have not done the short carbine length on them yet, so this is an area I'd love to talk over with those that have.

Anyway, if you would not mind "talking shop" a bit, please get in touch with me
Sorry Wyo, I didn't notice this post til now cause I don't subscribe to it, and since it's somewhat relevant to the thread I'll respond here. I bought a KAK barrel which for some reason Kurt makes at 19"--maybe a timing thing. The problem with 358 win "catching on with auto shooters" might simply be it's a heavy barrel due in part to it's caliber--might be worth investing a bit extra in getting a fluted/modified contour. The projectile is a walloping bullet out to 250 to 300 yds+; but after that it starts to "rainbow" it's trajectory even though it still has plenty of energy. If you were contemplating long shots at big game--I probably would look at longer barrels. I also built a 338 federal AR--and the two are very similar IMO in over-all range/energy parameters--but from what I've read you have to be pretty careful in your bullet selection for the 338 fed--it's a real balancing act finding the right bullet for the right range/velocity--meaning the expansion and penetration characteristics can be highly variable. All that said--I haven't used either for hunting yet because my builds came out heavier than I'd thought would be manageable for a long hike in the woods (which is another way of saying I'm becoming a wimp in my old age).

In reference to your magazine issues--I don't recall having a problem with either caliber as long as the magazine doesn't have the front feed tabs. However I was out shooting the 338 fed the other day and it seemed I was getting intermittent feed problems on the 3 rd cartridge of each magazine. It was bitter cold too so I thought maybe that might have been a factor. Maybe I'll break them out and mess with them after I'm done with a few other projects.

just noticed your chrono request--I can't seem to find any for the 358 win (I know I had them--but my computer goes down a lot). Here's a good one for 338 Fed (200 gr hotcor w 52 gr 2000MR) which is very accurate out of my Wilson combat barrel

Attached Images
File Type: jpg 338fed52gr2000MR.jpg (47.2 KB, 263 views)
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Last edited by stagpanther; February 23, 2020 at 09:21 PM.
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Old February 24, 2020, 07:17 PM   #16
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Quote:
Originally Posted by Nine2Five View Post
Depends on what you want. If money wasnt an issue I would get a lwrc repr. If you want to build it then a
Aero precision is great. A light rifle path would lead me to POF revolution. I also like the hk417 and the ruger sr 762.
You don't really have to build the Aero's, lots of choices out of the box but accuracy can be mixed. My 20 inch 5r .308 Aero is really accurate, 1 moa or better, my 16 inch one was always more like 2 moa (and there is kinda no good reason why).. reviews are mixed but so are ammo and shooters, and I ain't very good...

For something where accuracy is king, I would buy an M5 upper and handguard pair, pick another brand of higher end barrel, and run an adjustable gas block - but one could as well try one of their 20+ inch stainless barrels in a pre built upper and upgrade later if need be as well.
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Old February 26, 2020, 05:34 PM   #17
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The man in the brown truck just dropped off a 243 Win. Barrel, 22 inch, 1 in 8 twist. It was very on sale and I couldn't resist.
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Old February 27, 2020, 06:15 PM   #18
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So I built a 6.5 CM ar10. I like it a lot due to the less recoil.
I really hate shooting 308 because after a mag or two, it is just painful.
I can shoot 200 rds of 6.5 and not even notice it.
I also like being able to see my hits at 800 yards because I don't have to move much to get the scope back on target and I have a couple seconds to do it as a bonus.

I was able to buy a PSA 308 upper for like 299 and the lower for 179.
I picked up a BA barrel on sale and was able to rebuild the gun with a bleed off gas block and new guard for a total under 700 bucks.
I added an 800 dollar scope and was able to shoot out to 800 yards with good hits.
wind was too crazy to get to 1000. I hope to get out to 2000 later this year.
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Old March 1, 2020, 12:17 AM   #19
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I have a .308 and a .260Rem and I love shooting my .260 more to be honest.

I would expect that a 6.5C would be a better build.
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Old March 25, 2020, 06:39 PM   #20
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Have qny of you ever built an AR-10 in .300 WSM?
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Old March 26, 2020, 01:56 AM   #21
stagpanther
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I've thought about it, but exotic brass has held me back from doing any of the WSM's.
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Old March 26, 2020, 08:31 AM   #22
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WSMs have a pretty significant amount of bolt thrust. That has given fits to owners of firsermas other than very strong bolt actions. The belt is a function issue on auto-loaders as well. Looking at the operation system of the AR10, even if you get the gas volume low enough for reasonable cycling, I'd not even consider it for those reasons.
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Old March 26, 2020, 11:10 AM   #23
Ben Dover
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Mark, I thought the WSM rounds had replaced the belt with a rebated rim????

What am I missing???
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Old March 26, 2020, 12:37 PM   #24
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Me not being clear and using enough words.

You are right, WSMs and most of the new magnums, no belt. Was thinking of the guys that have tried to use belted magnum cases in AR10 patterns as wildcats mostly.
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Old March 26, 2020, 01:36 PM   #25
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Thanks. I thought I'd misread the WSM data.
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