6mm AR Turbo 40 Deg VS 6.5 Creedmoor AR10/SR25?

[Romulus]

I'd love to hear from some guys that shoot either or both the 6m AR and it's variants and 6.5 Creedmoor AR10's.

One would be a great little target rifle and coyote killer for moderate ranges, and the other would push hunting ranges out another 300 yds or so.

It's the old weight and cost vs performance dilemma. I shoot 260 AI right now and the 6.5 CM would offer more portability for realistic shots but something keeps nagging at me to build an AR15 in 6mm AR Turbo 40 deg.

Any insight or experiences will be greatly appreciated.

6mm AR Turbo 40 Deg info
http://www.6mmar.com/6mmAR_Turbo_40_Improved.php

 

[jonbearman]

What do you mean by more portability with the creedmoor versus what you already have?

 

[Romulus]

I shoot a 28" bolt rifle with a Tubb brake on it.

 

[GSPV]

If you want a bolt gun, build a 6.5x47 Lapua. If you want an AR on an AR platform, build a 6 or 6.5 on the 6.5 Grendel case.

 

[Romulus]

I guess I should have been more clear. I love my bolt gun 260 AI. Just looking for direction on my first AR platform whether to go with a 6mm AR or 6.5 CM in SR25.

 

[5spd]

I built an AR15 in 6x6.8 for coyote & antelope, 22" BHW 1/10" tw bbl.
It was a perfect match and slapped coyotes like a locomotive hits a semi stuck on a RR crossing.
I decided the 6.8 case was more to my needs/usages over the Grendel case & no fire forming.
Accuracy from 100-700 yards was super with 55-95g bullets.
I sold it to build a 6x6.8 on a bolt action & a lighter rig, but it will be 1/9" twist this time.
I don't think you will go wrong with a variant on the 6.8spc or Grendel case.

 

[Erud]

I'm a big fan of the Turbo 40. I've shot over 9000 rounds of it in NRA OTC competition, with a bit of Mid Range Prone mixed in as well. For that type of shooting, I think it's pretty tough to beat. Not sure if you are into that sort of thing, but since you mention owning a Tubb, I'm guessing maybe so? You also mention the Tubb having a brake, so maybe not? Anyways, it is absolutely reliable in the AR15 platform, and the only time I've ever had issues with mine was a couple of years ago at Camp Perry when I got caught in a downpour and literally had to pour the water out of my rifle prior to shooting. The biggest advantage over the 6.8 case is that you are able to load 105-107 class bullets to mag length, if that is a concern for you. Grendel brass is more expensive than 6.8, but the Lapua stuff is excellent, and should last a while if you don't abuse it. The first season I shot mine, I was loading 30.1 grains of Varget. It was very accurate, but was wearing out brass very quickly, like 2-3 firings and primer pockets were toast. I've since backed it down to 28.5 for 95 SMK's and 29.0 for 105's and the accuracy is just as good, just a little slower. That charge gets me right around 2780 fps with the 105's. I don't feel like I am giving anything up to the bigger dogs at 600 yards and in, and I have shot a lot of clean 200's with it at 600. I've shot it in a few 1000 yard matches also, and it'll do ok if the wind isn't blowing too hard. It doesn't real have the speed to keep up with the big guys if the conditions aren't good though.

 

[Romulus]

Erud,

What barrel length are you running? I was hoping to get to 2850 with the 105 hybrids but it sounds like I might wear out the brass to fast.

 

[Erud]

My barrels are 26". Just out of curiosity, why 2850?

 

[Romulus]

I like to use NF Velocity reticles for enhanced speed in the field if you can get a load to match up well. When you can work up a load to fit the scope you trade off some performance sometimes but gain a lot of predictability. Of course, if the rifle didn't want to shoot there i'd have to make other adjustments lol. Thankfully with my 260 AI it matched up perfectly and adjusting for higher or lower DA is not hard at all past 800 yds.

This image is of a 105 hybrid at 2850. Since it's an AR the sight height will be different and I haven't gone through that yet to see how much difference it will make.

This combo won't be as impervious to environmental changes as my 140 hybrid @ 3050 fps setup but with the high-ish BC of the 105 hybrid it should still be better than most loads and way more enjoyable to shoot.

 

[Erud]

Gotcha. You can get that kind of speed, but you *may* sacrifice some brass life. I never really tried very hard to keep up a higher velocity, as it shot just as well with a lighter charge and solved the brass issues. Also, for KD shooting, a little extra drop doesn't really make a difference. It's a great caliber for what it is, a mid-range cartridge that runs perfectly in and AR and beats the pants off the .223. It won't hang with full-sized cartridges though.

 

[mac86951]

6.5 Creedmoor out of an AR-10 is an excellent choice.

Magazines can accept up to 2.800" and some another 0.020 over that for long seating of heavy bullets, My 142gr SMK load is 2.790" and shoots very well.

Range reports in my neck of the woods has the AR-15 guys staying away from the AI or 40° necks for feeding "pickyness." I'd put a lot of thought into 6mm HAGAR though if you want an AR platform cartridge.

Bolt rifle, I'd make other choices than 6.5 CM. If you are looking for your first AR platform, it really depends on AR-10 or AR-15. AR-10 is non-standard, there are several styles and be careful, not all parts are exchangeable. AR-15 is easier, and that is what the 6mmAR is for.

Think of it this way: AR-15 mag takes 2.260" COL (some less, some more).

AR-10 takes 2.800" COL (again some less, some more).
I've seen a 7mmRSAUM with 180 bergers shooting 2950 from a magazine length load... (I'll take that for 1k shooting!) 6.5CM is an Excellent AR-10 round that really does well, and if you get nostalgic, a simple barrel change can net you a .308, or .308 based any cartridge. It'll be ~100fps slower than a straight 260, but you'll get a bit more than a 6.5x47. The pro to the 6.5x47 or 6.5CM in the AR platform means mag-length loads with the heavy high BC bullets.

-Mac

 

[Erud]

Range reports in my neck of the woods has the AR-15 guys staying away from the AI or 40° necks for feeding "pickyness." I'd put a lot of thought into 6mm HAGAR though if you want an AR platform cartridge.

I've read a lot of stuff like this on the internet, but have never seen it in real life. I've found no signs of this "pickyness" in my 9k rounds of first-hand experience with this cartridge. I have 3 other competitive shooters in my area also shooting this round, and I'd bet that between the 4 of us we have shot in excess of 20,000 rounds of 6mm Turbo 40. It isn't picky. I have 8 C-Products magazines that I use at every single Highpower match I shoot, and they all work perfectly.

 

[mac86951]

Range reports in my neck of the woods has the AR-15 guys staying away from the AI or 40° necks for feeding "pickyness." I'd put a lot of thought into 6mm HAGAR though if you want an AR platform cartridge.

I've read a lot of stuff like this on the internet, but have never seen it in real life. I've found no signs of this "pickyness" in my 9k rounds of first-hand experience with this cartridge. I have 3 other competitive shooters in my area also shooting this round, and I'd bet that between the 4 of us we have shot in excess of 20,000 rounds of 6mm Turbo 40. It isn't picky. I have 8 C-Products magazines that I use at every single Highpower match I shoot, and they all work perfectly.

Good to know the cartridge is sound, I'm guessing it depends on the smith/assembler then. As with any wildcat your experience may differ.

-Mac

 

[80x80]

Happy with 6MM turbo purchased from Robert Whitley.

Two years ago my son ordered a Turbo upper with all the up grades plus dies, brass, and 10 round magazines..

The goal was to have a heavy varmint and Wyoming antelope slayer. The upper was delivered in time for our 2013 antelope hunt and my son and I shared the AR to down two pronghorn bucks.

We are very happy with the turbo.

Bill

 

[tonysnoo]

Erud,

What barrel length are you running? I was hoping to get to 2850 with the 105 hybrids but it sounds like I might wear out the brass to fast.

I run my 6mm fat rat (6mm ar turbo clone) with coated hybrids at 2870 with CFE 223 ......absolutely no brass issues. We got loose primer pockets trying to run 4895 and 140 as fast the CFE. The faster powders do get slightly better accuracy, but at a cost of about 100 fps to keep brass. I'm running a 26" barrel so it does make it a heavy ar.

It's one of those rifles that keeps ya grinning.....good luck!

 

[flatlander]

I had a 28" MR upper in 6 RAT for a season, and never had a single feeding issue with it. Far as I'm concerned, the only downside to the RAT/FAT RAT/40* Turbo is bolt lug breakage when the owner tries to push 105s too fast. We always used LMT Enhanced bolts in our RATs and never had a lug break - but I don't believe LMT makes them anymore.

The source for Hornady 6 HAGAR brass has dried up - Hornady has no interest in commercializing the HAGAR, nor in making another run of the brass. That's more or less from the horse's mouth, coming from the guys who were distributing the HAGAR brass.

The 1st AR10 I built for myself is chambered for 6.5x47 Lapua, with a 28" Krieger 1-8tw bbl that I contoured out of a straight 1.25" blank. It weighed just over 9lbs when I started in on it, and wound up at just over 4.5lbs when finished - bbl is 1" out to gas tap (which was located 2" forward from std. AR10 rifle port location), .810" from tap to muzzle. It's a shooter with 123s & Hunter ball powder - just hate to use it where it's likely I'll lose a $1 piece of Lapua brass. Rifle weighs 13.5lbs with a Sightron SIII 6-24x50 mounted.

Back to the RAT - after selling the MR upper, I built myself an AR15 rifle in 6 RAT with a 24" Krieger, again contoured from a straight blank (starting to see a slight macho tendency here? - next time I need an AR 15/10 bbl blank, I'll order it already contoured). Used the last Enhanced bolt I had for this one, and love to shoot it. It hammers at 600 with mag length S95MKs & RL15, though I'm sure it'll also do very well with 105 Hybrids single loaded. It weighs right at 11lbs, also with a SIII 6-24x50.

Finally decided that the RAT should be attempted on a bolt rifle, so purchased a CZ 527 carbine in 7.62x39 in order to get the correct bolt face. Pulled the OEM bbl and replaced it with a 24" Krieger 1-8tw in #3 sporter contour, after reducing the shank dia from 1.250" to 1.070" to better match the action dia. This little sweety has a very nicely grained stock of Turkish walnut, and weighs 7.5lbs with a Sightron Big Sky 4.5-14x44 mounted in the factory steel rings. Only issue with it is that feeding out of the factory magazine isn't always perfectly reliable, but after tweaking the mag feed lips, it's acceptable for now. The action I really wanted to use was a Sako PPC repeater, but try finding one (as a complete rifle) for under $1400.... Whatever, the CZ gives acceptable accuracy, and is just the right weight to carry - though the magazine protrudes right at the balance point. Still carries great with a sling though.

I really enjoyed building & shooting all three of these rifles, but in all honesty, the little AR15 RAT is probably the best shooter of the bunch.

 

[TikkaSporter]

Since you've obviously been through more than one barrel on your 6mmART40's at 9000 rounds, what were you getting for accurate barrel life? At what point did you replace them? Accuracy reduction, or something else?

I ask because I think I'm getting to that point on mine. I just ran a few Tubbs TMS bullets through it and re-measured length-to-lands and adjusted OAL accordingly, hoping to milk a few hundred more accurate rounds out of it...

Your loads, velocities, and observations on case life are pretty much spot on with my experience. I started out at 30.3 gr of Varget with 105 gr Amax's and was losing primer pockets after about 4 - 5 firings. Now running with 29.6 gr Varget and a little bit more jump and haven't lost a primer pocket since, but brass still comes out looking a little beat up.

To the OP, I posted up some more information on the cartridge and rifle on the other '6mm Grendel' thread, so no point repeating it here... Needless to say I like the round and upper from Robert Whitley. It's a serious coyote thumper and more than adequate for the 5 mule deer that it has taken.

I've read a lot of stuff like this on the internet, but have never seen it in real life. I've found no signs of this "pickyness" in my 9k rounds of first-hand experience with this cartridge. I have 3 other competitive shooters in my area also shooting this round, and I'd bet that between the 4 of us we have shot in excess of 20,000 rounds of 6mm Turbo 40. It isn't picky. I have 8 C-Products magazines that I use at every single Highpower match I shoot, and they all work perfectly.

 

[Erud]

It's kind of hard to say for sure. I replaced the first barrel I had( a PacNor) with 2902 rounds through it. It was still shooting great, but it was the end of the season and I didn't want to start a new season with a barrel with that many miles on it. I replaced that barrel with a Bartlein and that now has 2655 rounds through it and is shooting great. I have another upper with a Bartlein with 3602 that will still shoot good at 600, but X-count isn't where it used to be. Still cleans 200 and 300 pretty easily, so I've relegated it to short-course matches and practice. I was actually trying to sell that one as I don't really need 2 of them anymore, but there wasn't much interest. I will likely re-barrel the one with 3600 on it and work it back into the full-course rotation.

So, I guess I'd say that 3000+ is definitely a reasonable expectation, even with 50% of that being rapid-fire shooting.