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AR 311K only $1091.36   W/ krieger 1-7.7 twist SS barrel
AR 15 223 entry level service rifle upper W/1-7 twist Wilson Barrel
Item # AR 340 only $749.00
Flat top SR with Full NM sights and carry handle W/ Wilson 1-7 Twist SS Barrel
Item # AR 311 ONLY $895.00

6MM Rat & FAT RAT Information Guide

History of the cartridge-

I had seen other 6mm Grendel Improved cartridges out there but there was not a source to just buy a barrel and parts to build your own. So I decided to design my own reamer and have a set of custom dies made for it. I had done this before for an AR-10 project that I did in a .243 wildcat cartridge. Lonnie Hummel of Horndays custom dies is very knowledgeable and helpful on this kind of project.

I worked out the reamer print for the 6mm RAT with the help of Lonnie Hummel from Horndays custom dies, John Hollinger from White Oak Armament and Dave Kiff from PTG. The reamer was designed to be used with Alexander Arms 6.5 Grendel Brass and for a gas gun. The dies were also designed for a gas gun. After the reamer and dies were made, John Hollinger sent me a test barrel to do the initial testing and everything looked good. John Hollinger asked me if it would be alright if he chambered other customer barrels in this cartridge and suggested I have a batch of dies made up for the cartridge.
I designed this cartridge initially for myself, but others have wanted to use it. I am glad to help other shooters and pass on the information that I have learned.

Greg Krebaum

Specifications

-Max case length 1.525
-Trim brass at 1.520 (Probably will not ever have to trim the brass because of the 40
degree shoulder.)
-Head Space 1.266
-Water capacity 36.7- 37.0

-OAL to the lands
108 Berger 2.338
105 Lapua 2.335
105 Berger vld 2.389

-Magazine length for the c-products mags are 2.28 – 2.29 oal
You can cut the front out of your mags if you want to get a longer oal for your
magazine load

Reloading

-Chamber was set up so 108 Bergers, 105 Lapua, 107 Sierra, boat tail juncture would be at or slightly below the neck shoulder juncture of the brass. 105 VLD will be approximately .040 above the neck shoulder juncture.



These loads will not work with the RAT

Always remember to start low and work up to the MAX loads
Further load testing will be done as time goes


The case must be resized from 1.264” min to 1.268” max using a stoney point “B”.350 head space bushing



Fireform loads are 30.0 Grains of Re-15 or 28G of H4895 with 105-108 bullets

Too light and you risk not completely forming the brass or even cracking the neck





6MM FAT RAT BULLET OAL LENGTHS
in a new chamber

BC OAL to OGIV OAL to TIP Max Mag Length Jump

105 Berger Hunting VLDS 532 1.882 2.37 2.260 0.089

105 Berger Match VLD 493 1.889 2.370 0.080

108 Berger Match VLD 511 1.889 2.337 0.047

95 Sierra HPBT 480 1.922 2.380 0.090

107 Sierra HPBT 527 1.926 2.372 0.082

85 sierra HPBT GameKing 311 1.885 2.175 0.000

The V-FAT RAT OAL will be .114 less than standard FAT RAT listed above

( start with one grain less than listed and watch for pressure signs as you gradually increase towards the max loads listed)

Lee's FAT RAT Long Range Loads
Start with 1/2 grain less than these MAX loads and work up to these, watching for pressure signs. Keep in mind that all barrels are not alike
6MM FAT RAT MAX Long range Loads
107 Sierra HPBT with 30.0 RE-15 ------------------2820 fps
108 Berger Match with 30.0 RE-15----------------- 2845 fps
108 Berger Match with 30.5 Varget-----------------2846 fps

These loads below showed no pressure signs and could be increased by 2 tenth increments until pressure signs show up

95 Sierra Match with 28.1 H4895------------------- 2792 FPS Min Load
95 Sierra Match with 28.7 H 4895------------------2860 FPS
105 VLD Berger with 28.2 Grains H4895
90 Berger 28.7 Grains H4895


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HOMESTEAD WEBSITES LOST MY PRODUCTS PAGE. PLEASE BARE WITH ME AS I REBUILD IT
AR U199, GAS BLOCKER PLUG FOR SIDE CHARGE UPPERS ( REPLACES CHARGING HANDLE) ONLY $7.50
6MM FAT RAT DIES CUSTOM BUILT BY JOHN WIDDEN
Custom 6MM Fat Rat Dies By Whidden, with micrometer seater
AR R290 0NLY 230.00
AR R291-1  W/SOLVENT PORT ONLY $31.99
AR R291-2 W/OUT PORT
 ONLY $19.99
Fat-Rat Pack, 6MM 1-8 Krieger Barrel, Barrel ext, bolt, Whidden Dies, Case guage, Bore guide,.936 MR gas block and +2.0" MR gas tube 


AR R293 ONLY $863.94
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AR MR293 ONLY 49.95
MATCH RIFLE HAND STOP W/ DETACHABLE SWIVEL, IN WHITE OR BLACK
AR 408 only $221.00
Wilson SS Service Rifle 223 1-7 twist barrel w/ext 20" long pre ban (post ban only $216.00)
AR 413 only $585
Krieger SS 223 1-7.7 twist 20" long  W/fitted bolt and wind adjustable sight tower
AR 414 only $545.00
Krieger 223 1-7 twist Match rifle barrel with Barrel ext & fitted bolt up to 26" long
AR 421 only $571.00
6MM Krieger 1-8 Fat Rat Barrel with Barrel Extension & fitted bolt
OTHER CALIBERS INCLUDE
  • 204 RUGER
  • 6.5 GRENDEL
  • 6MM XC
  • 6MM CREEDMORE
  • 308 PALMA
  • 308 FOR GAS RIFLES
  • 300SWM​
  • 6MM VARMINT FAT RAT
FAT RAT PACK
AR R288    ONLY $9.95
6MM FAT RAT CASE GAGE FOR STONY POINT STYLE 
THIS PAGE UNDER RECONSTRUCTION
AR U124 only $82.00
A2 Stripped upper reciever
ON SALE for $72.00
AR U123 only $250.00
flat top w/bolt handle right hand
AR 501 only $25.00
Butt stock weight
AR U132 only $145.00
match rifle float tube 2 "
                                      12.5" or 14.5" long
AR U131 only $145.00
match rifle float tube 2 1/4"
AR U125 only $100.00
a4 flat top W/M4 ramps stripped

AR U 124 only $115.00
with dust cover and fwrd assist

AR 502 only $30.00
Forend weight
AR V34 only $10.99
Bipod stud W/t-nut
AR SR301 only $535.00
Mark AR Leopold scope

AR SR-WVR-HIGH only 42.00
weaver Tactical 1" scope rings High-six hole
AR G288 only $65.00
Picatinny .750 Clamp-on Gas Block for Service Rifle
AR L63 only $38.00
Lower parts kit
AR MR292 only $23.99
Right Hand bolt catch release
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ONE LEFT IN STOCK
TWO LEFT IN STOCK
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AR B104 only $124.99
 complete .223 bolt carrier assy

AR SR211 only $12.00
forward assist kit
AR SR211 only 14.00
Forward assist kit
AR B107 only$59.00
complete 223 bolt assy
AR B303 only $65.00
.Bolt Carrier w/key & Screws
AR SR200 only23.95
charge hand complete
AR SR212 only $6.00
ejection port cover kit
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AR 421-2 only $491.00
6MM Krieger 1-8 Fat Rat Barrel 
Bolt Rifle 
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IN STOCK
Buy a WOA Mark AR scope with purchase of Flat top SR Upper and pay only $500.00 for the scope, reg $525.00