6mm AR Turbo 40 Reamer and questions

[mclarenross]

Im looking to build myself a new AR upper in 6mm AR Turbo 40 for use in both High Power matches and in Tactical rifle matches. I am a hobby gunsmith and would like to do all the barrel work myself and was wondering if anyone knows if PT&G has the prints for the Turbo 40 and I can order the reamer from them? I didnt see it listed on their wildcats list but I dont know how old that list is either.

Im planning on using the Berger 105 Hybrids, is the standard throat length good for these being mag fed?

I want to run a 2" extended gas system on the gun with an adjustable gas block, what gas port diameter are you guys finding works well for that length system?

Are standard barrel extensions working fine or should I use an M4 extension, or are yall modifying them additionally somehow?

Thanks in advance guys.

P.S. I emailed Mr Whitley with these questions but was told they could not give consulting.

 

[swehrman]

Search for information on the 6mm Fat RAT or 6mm RAT. It's basically the non-proprietary 6 AR Turbo 40.

-- Scott

 

[mclarenross]

Thanks for the response. Ive seen the Fat Rat as well but I like the little extra that the 40* shoulder gets me over the Fat Rat.

 

[infantrytrophy]

Thanks for the response. Ive seen the Fat Rat as well but I like the little extra that the 40* shoulder gets me over the Fat Rat.

Umm ... the 6mmRat and the FatRat also have a 40 degree shoulder.

The 6mmFatRat has a slightly larger neck diameter, compared to the 6RAT (and maybe in the case wall area - not sure about that). Both have a 40 degree shoulder angle, though, just like the 6mmAR Turbo 40 Imp.

The 6mmAR Turbo 40 Imp. is a great round, but it's proprietary. You can order complete uppers, die sets and other accessories from http://www.6mmar.com

The 6RAT is not proprietary. You can get a reamer to do the work yourself. I'm not sure if the FatRat is proprietary. Check this source: http://www.accurateandreliablerifle.com/products.html#anchor_262

 

[kperry]

PT&G lists the 6mm AR turbo 40 - as 6mm AR turbo improved

KP

 

[mclarenross]

Wow. I could have sworn that the Fat Rat still retained the 30* shoulder. So effectively there is no difference between the 6mm AR Turbo 40 and the 6mm FatRat. Thats great guys. Thank you.

 

[infantrytrophy]

Just to emphasize the point: there is very little difference between the 6RAT and the FatRat.

Here is the background on the development of the 6RAT and FatRat. They were developed as "open" or non-proprietary 6mm wildcats of the 6.5 Grendel. The 6RAT was developed by Greg Krebaum, and the 6FatRat was developed by Lee Wells.

The "gold standard" for brass is Lapua brass, or the same excellent brass sold by Alexander Arms with its "AA" headstamp. The neck of this brass is very thick, and becomes even thicker when necked down to 6mm. Some shooters found that the chamber neck diameter for the standard 6RAT was a little tight when shooting with the Lapua or AA brass, particularly for a gas-operated semi-auto rifle when shooting near-max loads. The 6FatRat, developed by Lee Wells, resulted in slightly larger chamber diameter in the neck and case wall areas - for better clearance. The difference between the 6RAT and FatRat is very small, and probably significant only when shooting the Lapua or AA brass (without turning the necks) in the AR. Sufficient neck clearance is important when shooting the AR using near-maximum loads.

The 6RAT would be fine for brass with typical neck wall thickness, about .011 to .012". If you use Lapua or AA brass, and you don't want to turn the necks, then the FatRat would be a more appropriate choice.