6mm turbo

[confuzed]

I am thinking about a 6mm turbo and was wondering what I could expect for speed with 105 grain bullet 24inch barrel in a AR-15 ( sometimes I think I am losing my mind for wanting another upper but what the heck!!)

 

[MrMajestic]

From our own Robert Whitley-
http://www.6mmar.com/6mmAR_Turbo.html

 

[tonysnoo]

I am thinking about a 6mm turbo and was wondering what I could expect for speed with 105 grain bullet 24inch barrel in a AR-15 ( sometimes I think I am losing my mind for wanting another upper but what the heck!!)

I'm interested in seeing what folks have to about this round too. I've been wondering if the turbo 40 is substantially better the the turbo. Seems like the turbo (30 degree) would be inclined to feed better than the turbo 40????

 

[rminut]

I have a 6mmAR turbo and would expect you would not get over 2800fps in a 24" barrel using "normal" loads. My barrel is 26" and barely get 2800fps before pressure signs start using RE15 or H4895 but each barrel is different so you really never know. It shoots fantastic so I don't worry about velocity.
As far as a 40 degree shoulder it doesn't give much gain in velocity, the barrel has more effect than the .5gr gain in powder, and there is no change in feeding. There are more 40 degree shoulder rifles in use and if there was a problem with feeding the boards would be full of posts talking about it.

 

[Cakes]

FWIW- I have 2 turbo 40's in 22" kriegers that feed flawlessly with about 2000 rounds between them. 108 Bergers & H4895 get approx. 2775' but they really shine with 90 Bergers & 87 V-max's w/H4895 @ 2880 and 75 V-max's & H335 @ 3050' love to shoot them but losing brass @ $1+ a piece is painful. One can never have enough uppers??? Fun round to shoot!! Eric in DL

 

[infantrytrophy]

... but losing brass @ $1+ a piece is painful. ... Eric in DL

Eric,

By losing brass, do you mean that you can't find it after it is ejected, or that the brass is damaged from over-pressure (e.g., loose primer pockets)?

 

[Cakes]

I don't usually use a brass catcher so losing them in the grass drives me crazy as the brass is expensive and it takes some time to prep the stuff. The brass itself is stout and shows no pressure signs and holds up well to many firings. Should have been a little more precise in my terminology. Eric in DL

 

[infantrytrophy]

... losing them in the grass drives me crazy as the brass is expensive ... Eric in DL

Understand. Me, too - been there, done that.

Randy

 

[tonysnoo]

How does the 6mm ar turbo40 compare to the 6mm fat rat? What data I found with a search indicates that they are/shoot really similar...true? Or?

 

[6fatrat]

They are very similar in velocity as well as accuracy. I don't have the specs. for the Turbo throat but the throat on the 6fatrat is to long. I intend to change this at the next re-barrel.

 

[infantrytrophy]

How does the 6mm ar turbo40 compare to the 6mm fat rat? What data I found with a search indicates that they are/shoot really similar...true? Or?

The Turbo40 and FatRat are very similar. I have a 6mm FatRat and have compared my fired and resized cases to similar cases belonging to 6Turbo40 shooter.

Pictured: 2 6mmAR Turbo40 cases on the left; two 6FatRat cases on the right.

It's almost impossible to tell the difference, even with measurements. Both are excellent, particularly for shooting in XTC matches. The short case allows you to shoot the high-BC 105-grain bullets, even loaded to magazine length in the AR.

The 6mmAR Turbo 40 is a proprietary chambering, developed by Robert Whitley (http://www.6mmar.com/6mmAR_Turbo_40_Improved.php). He sells complete uppers that have excellent reputations. His uppers are the result of his experience in testing and tuning (gas port size and placement, proper bolt to use, etc.).

The original 6Rat was developed by Greg Krebaum. The 6FatRat is a slight modification, developed by Lee Wells (http://www.accurateandreliablerifle.com/products.html). Both are non-proprietary - you can obtain the reamer, chamber the barrel and build the upper yourself - if you know what you're doing. They are based on the 6.5 Grendel case, necked down to 6mm, with the shoulder blown forward and angled to 40 degrees. As I understand it, the neck and upper body wall areas of the 6FatRat are slightly larger than those of the 6RAT to allow for a little extra clearance. When using Lapua brass for shooting in the gas-operated AR, the extra clearance is needed to avoid the need to turn the necks of the very thick-walled Lapua brass.

In terms of ballistics and performance, I don't think there is much difference between the two cartridges. Your choice should be determined by the experience, quality, customer service and reputation of the gunsmith who builds your gun. Based on my own experience and comments from others, the individuals mentioned above have excellent reputations. I would not hesitate to buy and shoot an upper from either of the two gunsmiths listed above.

Randy

 

[tonysnoo]

This round sounds so fun, I'm going to try it.

The fat rat is pretty affordable for me since I can used my existing match AR upper as a donor and rebarrel it.