I love this site except for the search function.  I didn't even find much doing the Google/Bing thing.  I'm guessing that tells me that this cartridge isn't a big choice as an option.  I'm a .243 reloader for a bolt rifle, and I think that's the main reason this caught my attention.  One of my AR10's was a .243 until I found it a little redundant to my 20" .308 AR10...so I made it a 16" .308 AR10.  If I read correctly all one has to do is open up the standard 5.56x45 case.  Well, I always keep my 5.56 brass and I have lots of .243 bullets, mostly below the 100g versions.  Looks like the 5.56 mags work fine, so all you need is a 6mm barrel.  Is that about right?...and anyone have any insight or experience with this variant?  Yes, I know there are tons of other, maybe better variants for the AR15, but I think I'd like to stay with something that remains totally AR15 except for the barrel...much the way 300 Black does.

Have not done one myself yet but I do believe the barrel is all that is changed.  Check out black hole weaponry.  They will cut you a barrel and have a caliber specific forum on their website.

Ive owned a boat load of them in the last 17 years...........2 bolt guns as well..........just a barrel change on any 223/556 rifle...........really shines with 80-85 grain bullets...........heavier bullets are best served in the .243 Winchester ............My HO..............

Run .223 brass through a set of 6x45 dies, not much else to it.  Much easier than converting to 300BLK.

Was shown the process just recently by a friend who does have a 6x45 AR.  It's a sweet shooter.

I have one (AR15) chambered for the round... easy to form brass... good deer killer with 85gr SP bullets.

Well, this is sounding more like a possibility.  I'm thinking of doing an upper to swap on to a quality AR15 lower that I have.  Any unusual buffer setup required as compared to 5.56?...and particular barrel source you'd recommend other than BHW?

Midway sells er shaw barrels that come with a bolt.  A few bucks cheaper than bhw.  I dont think they are as good of a barrel but im sure its hunting accurate.   I think ive read somewhere that if you call white oak armament they can cut you one but dont advertise it.

Is that ar15barrels.com site that I occasionally see pop up on some searches any good?  Initially I thought it was associated with this site but apparently not.  Don't want to start what is often a debate over the type of die, but for you folks who have been doing it, is the small base, taper crimp a requirement or not?

No buffer swap is need. Same as a standard 556/223.  Just put in a barrel and you can even use your original BCG unchanged.  

Hornady is the good $$ value dies and are labeled 6MM-223. I currently use Redding 223 bushing dies for the sizing and a Hornady 6 MM seater. No taper crimp or small base dies are needed. I  have four of the 6X45's in the safe at last count and have a new BHW barrel waiting to retrofit one of those to replace my 3 Gun set up I've shot for about 25 years in matches.

If you have a quality lower why not but a quality upper on it with a barrel built to your specs instead of something off the shelf.   My BHW LH railed upper has been doing well in 500 yard F-Class matches when I rotate it through my AR's.

PM me if you want some more information and I can get you set up and save you some $$'s on a barrel.

Greg

I have one of my ARs chambered for it, and love it. Brass is a breeze to make, I set my size/expander die in the last station of the 223 rem trimming toolhead for the 1050, brass goes in as 223 and comes out 6x45 ready to load. I use 75-85 grain bullets, i found the heavy bullets don't bring anything useful to the table so i trade them out to the 243 shooters for the lighter ones. I'm thinking of changing out my 223 R700 to 6x45 when the barrel gets shot out or i find killer deal on a R700 that i can steal the receiver and bolt out of.

I have a 10.5 in sbr one, it's a breeze to make and easy to load for. In SBR form it's ahead of the 223. 87 grain bullets at 2450fps? Check. 70's at 2550? Check. NT4 bore big enough to fire 6mms through? Check.

I wanted a kac pdw but the little 6x35 isn't going to happen, I figured if it's all that with a 65 grain bullet, a 6x45 with 70-90 grain bullet had to be Mo-better....and being unable to locate a micro xcr to convert to 6x45, made an AR. And I was right it's awesome. I might make a 20 in one day.

Edit add the "Brown Hornet"  Austrian fde.... with graphite black accents.. need the stock darker...

that is an awesomme SBR sir!  

IMO, probably the best chambering for a non handgun cartridge PDW type in our context of availible parts & brass, though the wolverine is pretty compelling too.

I wonder how it suppresses compared to a 5.56 of similar length.

Thank you!

this one sounds a little better through the NT4 than a similar 556. the griffin armament comp works pretty good, the comp is made for a  223, and serves as a mount for the NT4, had to bore the comp out some, the KAC suppressor has a large enough bore for a 6mm from the factory ( I did NOT modify the suppressor) , but that thing is LOUD with the can gone. Its a fun little rifle. I want a Micro XCR SBR with a 6x45 barrel. That would be the dream gun. Actually a friend and I used a reamer thats "6x45 Wylde" since it was a semi, and working was number one priority. the barrel is cut from a Bartlien 5R 1-8 twist that was pulled out of the build it was on due to a reamer crash. so we cut it up and made two 10.5 barrels. CNC lathe did the contour work, Jason did the programming, I pushed a green button once or twice, Jason will claim I did " most of the work" which is false...lol hes the machinist, im barely an assistant.... it is a pretty damn accurate rifle. Ill get a picture of the contour when I get home. I also have a pdf possibly with some really broad range loads for the 6x45 to give anyone a rough idea. I use 25.0 H322 with the 70 sierra, and 25.0 H4895 with the 87 Hornady. Compared to a 223, you can reaaly put a lot of powder in there for the heavy ones. most of the loads I looked at, I dont think I could get the max load in the case, it would overflow before i got close. its a very forgiving cartridge as far as loading, most of the 223 powders work too so its very easy to get into one. If your thinking about pulling the trigger on one, don't be shy, you will be pretty pleased with how it performs.

Mine is a 6mm TCU - think of it as a 6mm/223 improved.  Very fun and accurate build.  I even use it for the small coastal Blacktail here in OR.

Here is who built mine:
Kurt Buchert
Post Office Box 1398
Sulphur, LA 70664
(337) 853-2556
[email protected]


Here are some details:
http://www.ar15.com/forums/t_3_121/619352_6MMTCU___AR_project.html

Bill in OR

The tcu is pretty nice round as well. Shows what you can do with a little case.