Here's another pic

 

Ive heard of it before but dont have any experience with it. There is a somewhat popular wildcat 6x47 which is a .222 mag necked up to 6mm.

Also checked Redding's catalog. They list a 243x223 (6x45) as a class "C" which is a special order, but not custom status.

 

6mm TCU
6x45rem
6x47rem
All very similar cartridges, I opted for the 6x47 and am very pleased with it. One problem I never solved is getting it to feed multiple cartridges from a 700 magazine, other than that the gun is perfect.
As far as custom rifles go it was a very inexpensive project, without the scope it was right at a grand for everything, new 700 in 223, dies, barrel and gunsmithing by Douglas. Less than two months from start to finish.
Second cartridge from the left next to the 223. I get 2750 out of a 95gr. matchking and 2650 from the 115 D-Tac bullet, the 115's are amazing in the wind, on par with the 6.5 142's.

 

243/in a 222 or 223 case have been a bit popular in Aus .
ADI powders might have some info and the Aus shooters forums should i am pretty shore i read an article a while ago.
I read one about 243 in a 222 mag case that was popular and still being used , popular with roo shooters.
There was one for sale , i can't think of the name but if i come accros it i will tell you.

 

Have a 6x45 in a Ruger M77mkII V/T with custom stainless bbl in 1:10 twist. Sub MOA using 55 to 70 gr bullets. Easy on shoulder, brass and a joy to shoot.

 

My Remington has a 1-8" twist, recoil is slightly more than a 223. What is amazing about these cartridges is that the MV's are not much slower than a 243 even though most of the loads use only about 27 grains of powder.

 

I used a.223 4 years I have since gotten rid of just about every gun I ever owned and got the 204 Ruger if you have any questions about the ability of this gun just shoot it one time I have killed deer at 300 yards coyotes at 600 yards there is nothing like this gun it is the greatest

 

My 6x45 (OP's original inquiry), has a 26" custom barrel by D A Van Horn of Gilbert, Az. Using 25.0 gr of AA 2520 for the lighter bullets and 24.5 gr of H322 for the heavier, velocity avg's for all are in the 2600 to 2650 fps range. They can be loaded faster, but I find them the most accurate and very comfortable to shoot. I'm just punching paper anyway, not varmints.

 

BLC-2 is the powder for the 6x47, loading density is much better than even the short grained extruded powders.

 

Thanks guys I did some more digging around, and the round I "created" is a 6x45. The dimensions, etc are the same as a 6x45. What a neat round! Anyways, I was reading that since it's not a SAAMI spec cartridge, chambers will vary depending on who built the reamer. What does that mean when purchasing reloading dies? I can get a set from RCBS or Redding, but don't want to spend the money on dies if it won't fit the new chamber properly. What is the best for me to go about making sure dies/chamber will match up? Or am I worrying about nothing?

 

6x45 has been around forever, the dies and reamers have to be somewhat standardized after 50years?

My dies match my chamber perfectly, never really thought about it when buying them off Amazon!
I did form 3 cases with the new dies and send them to Douglas at the same time I sent the gun.

 

Sending fire formed cases to the custom die maker of your choice.
Thats what i'd like to do with some of my guns.

223 necked up to 25 cal is suposed to be a nice chambering ,can't remember what that one is called either .
Every change i have read or heard about sounds like it is better than .244 , makes one wonder why the army chose it.

 

Sending fire formed cases to the custom die maker of your choice.
Thats what i'd like to do with some of my guns.

223 necked up to 25 cal is suposed to be a nice chambering ,can't remember what that one is called either .
Every change i have read or heard about sounds like it is better than .244 , makes one wonder why the army chose it.

Was in the groc store yesterday and read a shooting rag. I may have to go back and get it.

The interesting article was about necking a 223 up to 25 cal..in an AR. All youneed is a new barrel. Everything else works on the 25 as it does on the 223.

 

Wes Ugalde beat ya to it! He also had the insight to incorporate P.O. Ackley's 40* shoulder on all the TCU chamberings.
Sweet shooters for the contender lovers out there.
Rather than expand the neck for larger caliber, Ruger uses the .222 Rem Mag and necks it down for the .204 Ruger!

 

I have been shooting a 6mm/45mm (or .223) for decades.... in my modified Ruger Mini-14 Stainless Ranch Rifle ... I had a new barrel made for it by the folks at Accuracy Inc. and it now shoots sub. MOA with the proper loading....
Ironically that is a Sierra Game King 6mm. 85 gr. Hollowpoint bullet with a medium fast powder ..
No trouble with cycling and is wonderful as a semi-auto ... reloads with RCBS dies etc.
Fun to shoot and legal for big game whcih was the motivation to change from 5.56 to 6 mm. so I could legally shoot deer -- as here 6mm. is the minimum legal bullet size for Deer, antelope and on up ...

 

I keep seeing the mention of the 204 Ruger in this forum as in pertaining to deer hunting. While I agree that it is a awesome varmint round, I am going go flip out the next time I hear of someone using it as a a deer round!!!! It absolutely is not a deer round. Anyways. The thread was on the 6x45, no the 204. I really appreciate all the info on this round, I believe I'm going to have my 223 m77 rechambered and bored for it. I already have a couple 223s and a good selection of 6mm bullets so, it will be something fun to play with!

 

The 6X47 has been a popular benchrest competition match cartridge for 25+ years. Very popular at one time especially with 70 gr, bullets. The 6mmBR, 6mmPPC, and other similar "small .243" cartridges" are still widely used.

 

6x45

I use 26.5 grains of AA 2230 and a CCI450 primer with a Sierra 70 gr MK king to get 3180 fps out of a 24 inch Bartlin barrel 1x8 twist. The Western Powder AA, website has a load catalog that has many loads for the 6x45.
I chose the 6x45 over the 47 because of an abundance of 223 brass. I bought my Hornady dies for $29.95, and rented the chamber reamer for $30.00 including shipping. Some folks don't think much of Hornady dies but this rifle will shoot .375" groups at 100 with ammo loaded with these.
With the 1x8 twist I can shoot 105 gr Amax very accurately although slowly at about 2700fps.
Except for the recoil pad and the rubber barrel tuner my rifle could be a twin of Kevinbear's.
The rifle is a pleasure to shoot.
Ferret Master

 

I use 26.5 grains of AA 2230 and a CCI450 primer with a Sierra 70 gr MK king to get 3180 fps out of a 24 inch Bartlin barrel 1x8 twist. The Western Powder AA, website has a load catalog that has many loads for the 6x45.
I chose the 6x45 over the 47 because of an abundance of 223 brass. I bought my Hornady dies for $29.95, and rented the chamber reamer for $30.00 including shipping. Some folks don't think much of Hornady dies but this rifle will shoot .375" groups at 100 with ammo loaded with these.
With the 1x8 twist I can shoot 105 gr Amax very accurately although slowly at about 2700fps.
Except for the recoil pad and the rubber barrel tuner my rifle could be a twin of Kevinbear's.
The rifle is a pleasure to shoot.
Ferret Master

Post a picture of it, I would love to see another persons "vision"!
Try BLC-2 with a standard federal 205 primer or 205m, you might be surprised at the results.
And btw a 105 at 2700fps from a cartridge this small is nothing to hang your head over, it's pretty great actually!

 

If I'm not mistaken, the 6x45 or 6mm-223 was originally designed by highpower shooters to shoot "across the course" in the days before the 69 and 77 gr 5.56 bullets. Hornady reloading dies are very reasonably priced. I believe the cartridge is SAMMI spec. I built my rifle from a Savage M10 .223 with a 9 or 10 twist Douglas barrel. It's a Coyote slayer! 1 pass thru the sizing die does the trick. No fancy case forming. I shoot the 70 gr Speer bullet for Coyotes, 85 gr Sierra game bullet for deer size critters. I like H335 for this round. I'm thinking about an AR upper in this caliber. Black Hole Weaponry makes a good barrel for the AR platform as does the Midway USA "AR Stoner" brand. An added plus is the round works thru AR magazines without alteration.

Tracker401

 

I've considered getting a 6x45 upper for my AR often, it would boost the power level up a notch making it a really good coyote gun.

 

One of my back burner projects is a 6x47 Rimmed. Have the brass, have the reamers, have the dies, have the barrel blank, but still haven't found the round tuit. Will be built on a Winchester High Wall, hence the use of the rimmed case.

The availability of a wide range of bullet weights and constructions makes it a winner in my book. Anything from 60 grain varmint grenades to 105 grain deer bullets. Lotta suppliers of benchrest grade bullets, too. Not like the .25 calibers, where thin-jacket varmint bullets have to be hand made.

 

Both the 6mm TCU and the 7mm TCU have been around for a long time and are both incredibly accurate cartridges. I have the 7mm TCU in both a carbine and a T/C Contender pistol. My personal preference is for the 7mm TCU cartridge as a hunting cartridge. It works very well on deer out to 200 yards. For both calibers, you just expand the neck of the 223 then fire-form the case with a moderate load too give it slightly more capacity. From my experience, the best brass to use for forming the 7mm TCU is S&B brass because I get almost no split necks and the case capacity is very uniform. Military brass has been much more troublesome for me to resize.

 

Trap: Pull up Hodgdon's 2004 Annual Manual, Pg.72 and you'll find data on your 6X45mm (6mm-223). It falls between the 6mm-222 and the 6X47.

Will

 

Ok so I was messing around today, I necked up a 223 to 6mm. Has anyone done this?

The U.S. military actually: they called it the 6mm SAW; trying unsuccessfully to turn the .223 into something it just doesn't have the necessary boiler room to be.

They need to try again, using the 6.8 SPC case, only in .25 cal, not 6mm. [Yes, I realize this sounds like going backwards, taking the 6.8SPC back to its roots in the .25 Remington, but all they ever needed to do was build up the .25 case & run it at the higher pressure the 6.8 uses... no fatter bullet w/ craptastic BC required!]

 

I had a lot of fun with a 6x45 AR. I had the upper made up from a 1/8 5R twist Obermeyer barrel that I got off gunbroker for $10! I'd already had the barrel chambered and threaded for a Krag, then thought to build the AR. It was an amazingly accurate rifle and wish I had it back, I never did shoot it in Highpower competition, but I'm sure it would have been great with the 1/8 twist able to stabilize those needle-like 107gr 6mm match bullets.

 

I got to looking around on the net and found a company that takes the 6.8 and necks it down to 6mm with a shoulder improvement for the AR platform, they claim 3000fps with a 85gr bullet. That would make quite a coyote rig if the recoil is low enough to stay on target if you miss and need to go semi-full auto! At least that's what my coyote hunting partner calls it.
I'm in the process of a cosmetic makeover of my AR, I dislike the military look that they have and a good paint job makes them look more sport hunting like or less assault rifle like for lack of a better term.

Anyway, 6x223 interesting and useful modification for the 223, I went with the longer neck of the 222mag because of my choice of heavy bullets and wanting to squeeze every bit of case capacity from the small diameter case.
The 223 case is a much more practical choice for the conversion but the dies I bought were only about 20.00 more, I had no trouble finding brass but did have to buy it, no doubt 223 brass can often be had for free.
I had mine built for highpower silhouette after having rotator surgery on my right shoulder and was able to compete again in 6 months, the 115grain bullets will not topple the ram target unless there hit high in the back or in the butt. It's a limitation I'm willing to live with because heavier calibers are out of the question due to the recoil.

 

I've considered a 6x45 for my AR hunting as only modification would be a new barrel. Everything else is the same and several boutique ammo companies load for it. There are necked up versions 25-45 SRC, .277 Wolverine. I've decided to go for the larger case capacity of the 6.8 SPC II. Here's another recent threads on it.

https://www.shootersforum.com/wildcat-cartridges/20502-reloading-6-x-45mm.html
https://www.shootersforum.com/black-rifles/91730-ar-15s-hunting.html
https://www.shootersforum.com/black-rifles/89677-ar-15-6-8-7-62-x-39-a.html
https://www.shootersforum.com/wildcat-cartridges/102901-6mm-wildcats.html
https://www.shootersforum.com/rifles-rifle-cartridges/95232-src-25-45-a.html
https://www.shootersforum.com/wildcat-cartridges/92805-5-56-6-0-a.html
https://www.shootersforum.com/wildcat-cartridges/88386-6x45mm.html

CD

 

I have AR's in 6x45 and .25x45 and they are both fine rounds!! I've killed some fairly nice deer with the Sierra 85 gr HPBT out to 180 yrd and it kills very well with less noise, recoil and cost than the .243,

I'm on the verge of saying the .25x45 Sharps is a better round than the 6x45 for deer using the Barnes full copper but I have not killed anything with it yet. It might go with me tomorrow looking for black bears.

You certainly do worse with either. I like the .25 so well I just got a barrel for the AR in .25x6.8 but haven't shot it much so I don't know how it will do but have great expectations.

 

I shoot a 6 TCU for IHMSA,15" barrel 80gr bullet 26.4 gr powder gets me2400fps and has taken BB turkeys at 420 yds

 

. . . BB turkeys...

Turkeys of the size and quality Butterball would sell? Let me see if "BB" is in the abbreviations list of the thread in General Discussion about abbreviations. We could be talking about Bridgette Bardot, here...

 

I've got a AR-upper in 6mm-223 6X45MM it's a good round and shoots great.. Barrel is 1-8 White oak precision free float hand guard JP ent SS bolt carrier harris bipod..Lupold target scope.. fun..