6mmAR Turbo 40

[Rock Knocker]

Hello everyone, it's been a while since I've been here.

I'm looking into getting an AR15 chambered in 6mmAR Turbo, I used the search function and found a few older posts with people here shooting them but not all my questions were answered.

I am looking for barrel options. Over the last few years I have grown very fond of the polygonal twist black hole barrels, in a perfect world I would get a 22" BHW barrel reamed for the Turbo. What barrels are most of you shooting? An easy to find 5R barrel would be acceptable as well.

All the testing I have found online with the Turbo is with 105+gr bullets, I don't want to be completely dedicated to those heavy bullets, I want 85-95gr bullets to be the main focus. With 85-95gr bullets in mind in a 22-24" barrel would I be gaining much with the Turbo 40 over a 6-6.8 or 243LBC? The latter two chamberings much easier to come by, I could save myself a headache.

Other than that how has the reliability been with the 40* shoulder in a semi auto? And what is all of your opinions about this case?

 

[R.Morehouse]

I would take a look over at www.6mmAR.com and do a search, it may get your questions some more action.........Just a thought..

Regards
Rick

 

[Rock Knocker]

Good advice but I've already been through just about that whole site. All their test data is with 105+gr bullets. They had data for a 18" and 26" barrels. And of course, they are the ones trying to sell the product so they have nothing but great things to say about it, no forum ether.

I didn't see any barrels for sale, just a complete side charging upper.

 

[Sniper338]

Good advice but I've already been through just about that whole site. All their test data is with 105+gr bullets. They had data for a 18" and 26" barrels. And of course, they are the ones trying to sell the product so they have nothing but great things to say about it, no forum ether.

I didn't see any barrels for sale, just a complete side charging upper.

they wont sell just barrels... already tried.. lost my business...

 

[Sniper338]

you will probably have to buy a barrel blank and have a gunsmith chamber it that does AR barrels.

 

[Rock Knocker]

I was thinking about getting a barrel reamed. I figured it shouldn't be a big deal to order a 6-6.8 or 243LBC barrel then send it somewhere that has a Turbo reamer. I haven't checked exact chamber specs, 6x45 would certainly leave enough material to ream out.

My biggest question is how much I would gain with the medium weight range 6mm bullets over 6-6.8 or 243LBC. I'm also curious about the reliability with the 40* shoulder.

 

[Ledd Slinger]

I shoot a 243 LBC Turbo 40 in a bolt rifle. I have an upper/lower and 7.62x39 BCG to make a varmint rifle in an AR15 with my reamer as well.

I would say that if you're not going for 600-1000 yard shooting, there's really no reason for the Turbo 40 versions. Just go 243 LBC or 6mm AR. The 243 LBC and 6mm AR are the same chambering. The LBC was created by Les Baer to offer to the public as a reamer option that was just outside infringing on the patent righta of the 6mm AR. Its only is a hair different by a couple thou here and a couple thou there

 

[flatlander]

Same could be said for the 6 FAT RAT, which is very similar to the 40 Turbo. Lee Wells handles selling dies for this chambering; I've never dealt with him, so don't know whether he sells bbls or not. A friend of mine designed the 6 RAT when the guy who runs 6mm AR wouldn't sell just a bbl for the 40 Turbo version, then later turned all his info over to Lee, who made some minor changes to the original RAT reamer print & re-named it FAT RAT.

I've done several AR15 bbls with an original 6 RAT reamer; never had an issue with any of them not running smoothly. Have also re-barreled a couple of CZ527 7.62x39 carbines for the RAT; issue there was not being able to single-feed 105s loaded too long for the CZ magazine due to the claw extractor. More recently did a RAT bbl for a Howa Mini that came from the factory with a 6.5 Grendel bbl. No problem single loading long rounds with 105-107gr bullets there, since it's a push-feed design.

 

[steve123]

I was thinking about getting a barrel reamed. I figured it shouldn't be a big deal to order a 6-6.8 or 243LBC barrel then send it somewhere that has a Turbo reamer. I haven't checked exact chamber specs, 6x45 would certainly leave enough material to ream out.

My biggest question is how much I would gain with the medium weight range 6mm bullets over 6-6.8 or 243LBC. I'm also curious about the reliability with the 40* shoulder.

The 6mmFatRat or 6mmART40 is right around 100 fps faster than the unimproved versions. My current 6mmFatRat data is based off a 8 twist 22" Wilson barrel in a AR. 29.4 grains of H4895, CCI450 primer, Lapua formed brass, gives 2870 fps with a Sierra 95gr SMK at 2.245 OACL. I've got the varmint chamber Lee offers because my intent is semiauto only. I tried to make the Berger 105 hybrid shoot well but is was not to be, heck every 6mm bolt rifle I've had loves those. Thankfully that 95SMK shoots very well and wish I had tried it sooner.

I had the 6mmAR T40 before which I did some learning on.
It didn't like 105JLK's at mag length. 105amax it did like. I used hot loads which made the barrel extension loosen up within 700 rounds. The hot loads I found out later were the source of occasional malfunctions due to too much grip on the chamber. After the sorting out it was reliable.
Load #1 which was that hot load with 105 amax, went 2885 fps at mag length out of a 26" Krieger.
Load #2 was much slower to preserve barrel life at 2740 fps IIRC.

Personally I think I will stay with the 95's because the BC is good at .5, they can be driven faster than 105's, doesn't intrude on the powder column as much, recoils less, and with a medium load I can't tell any difference in the wind compared to the 105's at mag length. I put a muzzle brake on the barrel later on and boy did it make a difference! I was pounding a 19" plate at 1122Y over and over until I felt guilty about the barrel getting too hot!

 

[lee1982]

Same could be said for the 6 FAT RAT, which is very similar to the 40 Turbo. Lee Wells handles selling dies for this chambering; I've never dealt with him, so don't know whether he sells bbls or not.

He does sell just barrels, which aren't all that pricey. His dies are from Whidden.

 

[Eric Leonard]

Same could be said for the 6 FAT RAT, which is very similar to the 40 Turbo. Lee Wells handles selling dies for this chambering; I've never dealt with him, so don't know whether he sells bbls or not. A friend of mine designed the 6 RAT when the guy who runs 6mm AR wouldn't sell just a bbl for the 40 Turbo version, then later turned all his info over to Lee, who made some minor changes to the original RAT reamer print & re-named it FAT RAT.

I've done several AR15 bbls with an original 6 RAT reamer; never had an issue with any of them not running smoothly. Have also re-barreled a couple of CZ527 7.62x39 carbines for the RAT; issue there was not being able to single-feed 105s loaded too long for the CZ magazine due to the claw extractor. More recently did a RAT bbl for a Howa Mini that came from the factory with a 6.5 Grendel bbl. No problem single loading long rounds with 105-107gr bullets there, since it's a push-feed design.

I was told that the CZ rifles were made so that the extractor would slip over the rim to load single shot,,,I have a 527V 223 Rem I have shot close to 5,000 rounds through with all but maybe a couple hundred loaded single and thumbed in the chamber and never caused any problems,,

I think Calhoun sells a Bob Sled type magazine that allows single feeding and lets the extractor go over the rim of the case and slides up between the boltface and extractor as you chamber the round,,

 

[tonysnoo]

I was thinking about getting a barrel reamed. I figured it shouldn't be a big deal to order a 6-6.8 or 243LBC barrel then send it somewhere that has a Turbo reamer. I haven't checked exact chamber specs, 6x45 would certainly leave enough material to ream out.

My biggest question is how much I would gain with the medium weight range 6mm bullets over 6-6.8 or 243LBC. I'm also curious about the reliability with the 40* shoulder.

I have both the fat rat and turbo40. They are virtually identical. I can very easily run 87s at 3025 with great accuracy. I prefer 108 bergers at 2860-2890. Cfe223 and 2000mr run just about identically. 2000 might be a bit cleaner. My brass life is great... still shooting some of my very old AA (lapua) brass, but they are pretty loose now. .. maybe upwards of 25 firings??

Accuracy is excellent with 87s and 108s at mag length. We fussed around with some feeding issues early on, but now they are set up to run like a clock. No fail to feeds in any of our 60+ round tactical matches.

6mmar.com sells barrel blanks already contoured, but Lee at Accurate and reliable will turn key a barrel for you. He has two chamberings One with a long free bore . You jump mag length 108s about .040 with that. The other a varmint free bore, that works with 87s pretty nicely. Of course I like it in between those two...lol

We have a number of these in our group. all have minimal throat issues with one exception well into the 2000 round range. The exception was one of our first barrels where we were trying so many different powders. Brass and barrel life was sacrificed with N140, Varget, 4895, etc, till we landed on CFE and 2000. Life has been good ever since.

 

[RampedRaptor]

I built a 6 fat rat varmint about a year ago and shot it twice.

First to break in the barrel/ FF brass and the second time to run ladder tests. Fantastic round but it just sits in the safe.

Thought about running it in PRS matches but my schedule is too busy.

22” is a perfect length in my mind. No feeding issues with Lapua/105gr bullets

 

[Rock Knocker]

Thanks for the info.

Does anyone know a good place to send a barrel that has a Fat Rat reamer. I don't plan on buying a complete side charging upper so the Turbo sounds out of the question.

 

[M.Stilley]

Thanks for the info.

Does anyone know a good place to send a barrel that has a Fat Rat reamer. I don't plan on buying a complete side charging upper so the Turbo sounds out of the question.

Lee Wells at Accurate and Reliable Rifle.

 

[RampedRaptor]

Lee Wells at Accurate and Reliable Rifle.

Yes. Quality work. Be ready for a wait and communication is hit or miss with him.

 

[Littlecooner]

I sent some of my components to Lee Wells and he chambered a barrel and put my upper together. Very satisfied with my Fat Rat. He was very easy to deal with and I thought the fees were very reasonable.

 

[Rock Knocker]

Thanks, I will keep all of this in mind. I've got a few irons in the fire right now and the barrel will be a couple month wait but this will be at the top of my list.

So far I plan on buying a 22", maybe 24" Black Hole Weaponry barrel and sending off to get rechambered. Have any suggestions on twist for midrange bullets with the occasional heavy bullet?

It will be mounted on an Aero Precision M4E1 upper with 15" handguard.

I'm still up in the air about a scope. I usually go with Leupold when the budget doesn't allow a Nightforce.

 

[papa]

I have both the fat rat and turbo40. They are virtually identical. I can very easily run 87s at 3025 with great accuracy. I prefer 108 bergers at 2860-2890. Cfe223 and 2000mr run just about identically. 2000 might be a bit cleaner. My brass life is great... still shooting some of my very old AA (lapua) brass, but they are pretty loose now. .. maybe upwards of 25 firings??

Accuracy is excellent with 87s and 108s at mag length. We fussed around with some feeding issues early on, but now they are set up to run like a clock. No fail to feeds in any of our 60+ round tactical matches.

6mmar.com sells barrel blanks already contoured, but Lee at Accurate and reliable will turn key a barrel for you. He has two chamberings One with a long free bore . You jump mag length 108s about .040 with that. The other a varmint free bore, that works with 87s pretty nicely. Of course I like it in between those two...lol

We have a number of these in our group. all have minimal throat issues with one exception well into the 2000 round range. The exception was one of our first barrels where we were trying so many different powders. Brass and barrel life was sacrificed with N140, Varget, 4895, etc, till we landed on CFE and 2000. Life has been good ever since.

Recommended starting point with 2000MR powder and 108's?

 

[5spd]

I assembled 3 6x6.8 rigs.
1 on a savage action, other 2 ar15s. I went with 1/9" twist for running 55 to 95g bullets, 22" on savage, 20" on ar15s.
My go to everything load is a 90g sierra TGK, at 3039 fps on top of h335.
No reason to run heavier for coyote, deer, antelope.
Brass is easy, 6spc dies from ch4 or 6.8spc redding bushing dies.
Ar15 Barrels from xcaliber, Savage was a p3 from BHW when they were good.
H335 is great for this caliber.
X caliber makes 6x6.8 ar15, bolt gun barrels.
I have no work with a turbo 40.