My Quest for a New Match Rifle – The 6mm/223 Remington
I know the current thinking is to build “Across the Course” rifles on an AR frame (space gun) or something along the lines of a Tubb rifle but I have always enjoyed shooting a bolt gun. I am currently in the process of wringing out a new rifle I chambered in 6mm/223.
I have watched a change in thinking for NRA High Power across the course in match rifles and calibers. There are several newcomers to the field; the 6mm AR, 6.5 Grendel, 6XC, and 6.5 Creedmoor. I have seen these rifles perform and all have done very well.
When I started this project I was looking for a cartridge that shoots and feeds well from a magazine or clip. I had shot the 223 Remington in my 722 Remington and knew it had fed well so I chose the 223 Remington necked up to 6mm.
The 6mm/223 gives me what I have in the standard 223 only with a better selection of bullets. I wanted a better 600 yard bullet with a higher B.C. than provided by the 80 and 82 grain bullets. I also wanted a 600 yard line bullet with a .500 or better B.C. for those shots that should be 10 ring or better but seem to find the 9 ring no matter how well I held and broke the shot.
My project started with ordering a 6mm barrel from Bartlein with a 1-8″ twist. I called Pacific Tool and ordered the 6mm/223 reamer. I found a used Remington 700 action at a local gun shop and already had a Remington 40X stock. I then started putting the gun together.
I called Jay at Redding and talked to him about the die set that would work best for this project. I ordered a Type “S” Match Full Length die set for the 223 Remington and long and short 6mm seating stems. I reamed a competition seater sleeve to accept the 6mm stems and then ran my chamber reamer inside the sleeve to cut the neck for the 6mm/223. I used the full length die with a .264” bushing and checked to make sure this had enough clearance for the case neck and die.
Next, I went to my good friend Neil Keller at “Kustom Ballistics’’ for some instructions on “blue printing” the action and chambering the barrel. We used Neil’s lathe for these operations. I had also purchased the following tools for these operations from Brownells: a Bolt lapping tool, Receiver facing mandrel, and a Receiver Accurizing System.
After making sure everything was straight and true we threaded, chambered and headspaced the barrel. Finally, we cut the barrel down to 27” and finished the muzzle with an 11 degree target crown.
After the metal work and stock work were done, I turned my attention to working up some loads.
I used Berger 70 grain and Sierra 70 MatchKings for my 200 and 300 yard loads along with Vihtavouri N540, Remington cases and Federal 205M primers. The initial load gave me .200” -.250” groups off of the bench at 100 yards. Thank God, not much load work up here. These loads were derived from the Sierra load manual using the 223 Remington Bolt-Action Data
The 105 grain load was a little more difficult. The accuracy was about the same but the extreme spread was too high, around 30-40 fps. I was looking for 20 fps or less, thus am still working on the 105 grain load.
Left to right: 6mm/223 – Berger 95 gr VLD and Berger 70 gr, 223 Rem. - Sierra 69 gr. and Sierra 82 gr.
I tried 95 grain Berger VLD’s with Vihtavouri N550 and RL15, both of these powders produced very good results. RL15 load has an E.S of 4 FPS and Vit N550 had an E.S. of 9 fps. No load data was available from published books so I worked the loads up from water volume and Quick Load.
Preliminary testing at 300 yards produced very good results. My first 600 yard match gave me the feedback I wanted. You only get 2 sighters in a match and for a new rifle with no 600 yard sight dope I was a little concerned about being on paper with the first shot. Fortunately, I grabbed paper but took 6 more shots to get zeroed. After losing some points for the zeroing effort, I shot three 9’s on the last 15 shots for record and the rest were 10’s and X’s. My score for that match ended up being a 186-5X.
Target shot at 100 yards in prone position with iron sights. 22 shots with Berger 70 gr. Bullets in 6mm/223 Rem.
I have more work to do on this project but so far this cartridge looks promising for what I wanted to accomplish. I will keep you updated on my progress.
The 6mm/223 is an old chambering but shouldn’t be overlooked if you are shooting an AR-15 configured rifle or want a bolt-action that will feed well in the rapid fire stages (National Match courses).
Ron Dague
Sinclair Tech Staff
NRA Metallic Reloading Instructor
800-717-8211
www.sinclairintl.com
rond@sinclairintl.com
support@sinclairintl.com
December 16th, 2009 at 11:12 am
How does this differ from the 6mm TCU?
Mike
December 16th, 2009 at 11:36 am
Hey Ron,
I just read your article with great intrest. Last year I jumped on the 6mm-223″across the course” band wagon by building an AR w/ a Lilja 3 groove 1-8″. Using a DPMS billet “lefty” upper with a Les Baer NM bolt carrier and bolt. I used an over weight tungston buffer w/ a Tubb flat wire buffer spring.The lower is a complete RockRiver w/ NM trigger. I worked the trigger over a little to get about a 1-1/2 lb 1st stage w/ about an additional 6-8oz 2nd. With a lead stock wedge it weighs in at 13lbs, 10 oz on an NRA certified scale.I loaded it w/ 90 gr Sierra fmj GameKings (I’m too cheap to buy real good bullets) to mag length and H-335 powder. My load was the “accuracy load” for the 6mm-223 with 90 gr fmj-GK in the 50 annivesary edition of the Sierra manual.
Just as you said… I showed up at the 300 yrd any-any fun match w/o any sort of trigger time on the gun. I talked the RO into letting me have 5 sighters for a total of 45 shots. I viewed the match as more of a test run than looking for an actual score. This is the first left handed gun I have ever shot in compitation and it was a blast. I could actually control the trigger and my breathing during the rapid fire stages. All 45 pieces of brass were in a pile about the size of my hat at an arm’s length from my waist. I couldn’t believe how clean the botl and carrier were after the match, just the slightest grey dusting over the parts.
I did have some-what of a problem though and I’m sure your bold gun won’t have this problem, but it might in the way of accuracy. When sizing up the necks on my CBC once fired brass I didn’t notice it while loading but I sure noticed it when I had several “failure-to-fire” rounds. All but one were in the slow fire stages and I didn’t bother to call “alaby” I just ejected the rounds and used another. The problem is the little dough-nut that formes when the 6mm tapered button gets material from the 223 shoulder for the bigger dia. neck. It’s not really noticable until it gets stuck in the brand new neck of the chamber. Then there is a .015″ -.020″ shiny ring at the base of the neck adjacent to the shoulder and very sticky when trying to pull it out w/ the charging handle. I pulled the misfires down and there is a noticable ring in the projectile. I thinck the bench-rester’s that turn the necks of their match ammo call it a “reverse” doughnut. If you’de like I could send you a few digital photos. I’m not worrying about it now until the spring, after the weather breaks and I’m thinking that after the inside of the chamber gets more broken in the jamming won’t be a problem. they use SR-C targets at these fun matches so the hunter types can get decent scores and feel good about comming back and shooting more matches. So I don’t really know how accurate my groups were. I got a really good score even with a miss in the sitting-rapid.
I realize I’v gone a little long, So… Thank You for your time, Joe Reno
December 16th, 2009 at 3:26 pm
I’ve shot an AR chambered in 6 X 223 for a few years. I found that the 95gr. Berger
is about as much as the cartridge will handle. Benchmark powder @ 25gr. (usual disclaimers) gives the best score, 190-6x. HTH, your friend in Florida, Lyle Palmer
December 16th, 2009 at 5:08 pm
Would like to know more about your rapid fire.
Was the reciever clip slotted or what magzine set up did
you use?
December 16th, 2009 at 6:08 pm
Hi, I just am wondering what all of this set you back? I will be very interested in the results that you have coming as yet. This is something that I have thought about in the past. Thanks, Ted
December 16th, 2009 at 7:08 pm
Nice article Ron! You guys are the best!
December 16th, 2009 at 8:31 pm
I’ve been looking at this cartridge for a few years now. What velocities are you getting, what overall length are you working with on the 95 gr / 105 gr?
Thanks!
December 16th, 2009 at 10:39 pm
I did the same thing to a mini 14. Rebarreled with a heavey barrel and flutted it ,also installed a brake. Chambered in 6mm/223. Works great.
Kevin
December 17th, 2009 at 9:36 pm
I’m working with a Hart barrelled Sako Vixen in 6×223 and also have great interest in this caliber. I’m sure that shooters may be hesitant to share specific load data due to concerns about liabilities, but I’d be interested in any load data any 6×223 shooters would be willing to share. As Lyle said above, I’ll honor “All the usual disclaimers” and take responsibility for my actions. You can send a PM to shaw.fe@gmail.com if you’d prefer. I have the Sierra and Hodgdon data. Please keep us posted on how things progress.
Happy Holidays from the Adirondacks in NY.
Frank Shaw
January 1st, 2010 at 11:24 pm
Would someone please answer Mike Landolfi question . . . how does this differ from the 6mm TCU?
January 4th, 2010 at 11:08 am
Jack,
Regarding the question about the difference between 6 tcu and 6×45 or 6×223:
The 6X45 AND 6X223 are the same. Most reloading manuals will have the case dimensions.
The standard 223 Remington case has a 23 deg shoulder and .022 taper from shoulder to base
The 6 TCU is an improved version of the 223 Remington case. The shoulder is 40 deg and there is .005 body taper from shoulder to base.
The 6 TCU has greater case capacity but not by much.
If you have any questions please call 800.717.8211 ask for Ron
Thank you
Ron