I was thinking about getting a 6mm-223 top end and I see the 6.8 is now offered by everyone and there brother. I'm thinking maybe I'll just get that top end instead.  Anyone have have them both?? Are there any advantages to one or the other.  I guess the 6.8 might be cheaper to get the upper but more $$ to shoot and such as you'll need new carrier mags and such.  The 6.8 is a 270 bullet and the 6mm is a 223 case necked up to 243 will the 6mm be flatter shooting etc.   762  

The 6 x 45 or 6mm/.223 is not really in the same class as the 6.8 SPC.   The 6 x 45 is extremely accurate, it began it's life as a bench-rest round.  It will produce about 30% more energy than the  5.56/.223 but not nearly the power that the 6.8 has.

The 6 x 45 is a wildcat, you would have to hand-load for it.  Although scarce, the 6.8 SPC ammo can be purchased.   The 6 x 45 uses standard AR mags and a standard bolt/carrier.  I have built many on both bolt-actions and AR-15's and it is a great cartridge.  Easy to load for and pleasant  to shoot.  I have won many matchs with the 6 x 45 and it has a special place in my safe!

Gatman762:
As Dtech points out these two cartridges are not really in the same class.  I have both the 6.8 and the 6x45, for the type of shooting I do the 6x45 works better for me as a varmint round.
The 6.8  is so far from all reports doing well as a deer cartridge out to around the 250 yard mark.

You need to ask yourself what roll you want this cartridge to fill. The best part about the 6x45 is all parts are standard except for the barrel, brass is easy to come by and cheap but you will need to load your own. With the 6.8 bass and loaded rounds are still hard to come by and the 6.8 needs a different bolt, mag and barrel.

Joe

Dtech1 and Jar,

A couple of questions if I may.

I am pretty unfamiliar with the 6x45, but I do understand the issues of bolt face size, chamber pressure and case thrust.  As the 6.8 has a larger case head, it operates at pressures below the 5.56.  If the 6x45 uses the 5.56 case head, are pressures similar to standard 5.56 round?  It would seem that the two should perform similarly froma pure velocity standpoint.  Is the limiting factor of the 6x45 a function of case capacity (or powder selection)?  I have not found very much information on reloading for the 6x45, but I am in the market for a midbore cartridge.  It sounds very appealing from the brass, bolt and magazine perspective.  Do either of you have velocity information from the AR platform?  All that I have at home is TC Contender reloading data.

thanks,

Craig

I shoot the 6x45 in a mini 14 and I've found it seems to have a lot more power than the 5.56/62 gr rounds.  She really is a sweetheart.

Last month, my dad and I were shooting at a telephone pole sized log at 50 yds.  We were shooting the mini with 75 gr Vmax and a AR with 62 gr FMJ NATO. The NATO rds did not seem to have much efect on the log but when my dad shot it with the mini, it knocked it over smartly.
We were both surprised  

I load a 75 gr Vmax for the rifle, that seems to be optimum for the cartridge vs OAL.  The problem you'll run into is that if you try to load an 85-90 bullet, you'll be encroching on the case capacity of the cartridge.  Even with  the 75 gr bullet, you are shooting a full case or compressed load in order to get the velosity above 2800 f/s.

It is one of the easiest wildcats you'll find but you do have to hand load every round.

BTW: This mini was worked over by Accuracy International about 10 years ago and with the right loads. she'll shoot .75" groups

Maddog,

Thanks for the info.  You confirmed what I already suspected, it looses out when the bullet weights are upped.  Still, a 75 grain bullet at 2800 fps is no slouch.  My problem is that I need an antelope cartridge, and I need the weight better than 75 grains.  I like the Barnes bullets due to the good performance with a lighter weight bullet, but, unfortunately, they are usually longer for caliber.  Not good for a length challenged round.

I have not ruled out the 6x45, I think that I need to do a bit more homework.  And, I reload just about everything that I shoot, pistol and rifle.  If you don't mind, what is the barrel length on your Mini-14?

thanks again,

Craig

Craig -

we started making 6 x 45 uppers partly to find a better outlet for left over .223 components from .458 projects.  As to your question on heavier loads, from a 24" barrel, maintaining 2.260" overall length and staying below 105% loads and well below max pressure, here are some predicted results

Barnes 85 gr TSX, 2775 fps
Sierra 85 HPBT, 2800 fps
Nosler 95 BST, 2640 fps
Hornady 100 gr BTSP, 2580 fps

All suggested using the same powder and leave room for higher pressure if desired.  The 95 gr load if maxed out on pressure suggests it will do 2720 fps

We can offer these with the ABS carbon fiber barrels to keep weight down while getting excellent heat dissipation

BB1,

I just went out to the safe and I had a 24" AR sitting next to the Mini and they were the same over all  length but the mini is much more handy, she has a 3/4" bbl vs the 1" on the varmint AR.  The actual bbl length is a little shorter but it looks longer because I've got the M16 flash supressor attached

I think this is a riflemans rifle

Really, for goats, this should work just fine if you can get within 150-200 yards of them.

I just loaded a lot of 30.06 with the Barnes 168's for my 1885 Browning, I'm planning to take them to the range tomorrow to see how they work (I expect a lot for the price

Where are you located in NM?

Maddog,

Thanks for the information.  I take the measurements to mean that the barrel is 22-24ish.  That helps, as it gives me some real world numbers.  All of my antelope shots have been under 200 yards..  The last one with the 458 was 75 yards.  Very long shots are only required if you have limited time, and do not want to stalk them.  I have never had a problem getting reasonably close, on public land with a little effort.  I live in Taos, NM.

Marty,

Thanks for the input.  I had not even thought of this cartridge, in our conversations with the other "items".  With the QCB, it makes adding barrels much easier (read cheaper), so I might be interested if you are.

You hit the nail on the head with the 85 Barnes.  That is exactly the bullet I was thinking about.  It would certainly be an experimental proposition on my part, as we have some interesting variables.  The Barnes is fairly long, which works against case capacity.  It is designed to give slightly better velocity due to less bearing surface.  But, this could require more powder as the pressures will be lower.  I think what I need to do is order a box of bullets and make some measurements.  The biggest hurdle I have is that the data that I have for the Contenders does not have any info on the newer powders for the 5.56, which I suspect are the right ones.  Any thoughts on the powder selection?  I do not need quantity, just type, so that I can look at case capacity.  I need to run the Barnes through my ballistic program to see where the magical 1600 fps hits in terms of range.

A carbon fiber barrel, 5.56 brass, bolt and magazines, the only downside is just a little less velocity than the 6.8.  This could be very doable.

Craig

So far the 87 grain is the heaviest bullet I have used in the 6x45. With Hornady 87 grain and Sierra 85 grain HPBT bullets you can load to mag length, and out of a 20" barrel can get a little over 2700 f.p.s. at 15' from the muzzle. I suspect you might reach 2800 F.P.S. with this bullet weight but did not want to push it any more than that.

This cartridge is just right for the bigger varmints, is pleasant to shoot an easy to reload. It is a good addition for anyone looking for something a little special.  My advice is get one and have some fun.

Joe

Hey BB1 (and others)

This sounds like a really cool thread.  
I just went out and measured my bbl and what I came up with was dropping a rod into the bbl with the bolt closed 23.125" minus .875" for the flash hider, that puts me right at 22-22.125" bbl length.
I've got a 1 in 10" twist on this rifle.

BB,  I've worked at the  mine in Questa just north of Taos. It was always a pleasure to be sent down there to help solve problems.  I love the food.  Is Roberto's still open?  Best tomales I've ever had, the trick was to find him open and not off fishing or skiing.

If you decide to go this route, let me know, I might be in the market for another upper, 20" bbl with flash hider would be cool just when I thought I had all the rifles I needed!

One other thing I might add when looking at this chambering.  The 6x45 looks very much like the .223.  If you're shooting a AR chambered for the .223 and another AR chambered for the 6x45, you really have to pay attention  to your cartridges, it's so easy to grab a box of 6x45's thinking they're .223's and visa versa.  
I'm not sure a 6x45 would chamber in a .223 rifle but I'm pretty sure the .223 would chamber and fire in a 6x45.  You would be in a world of hurt if you could get the 6x45 to chamber and fire in a .223 bbl.

I guess I could try to chamber a dummy 6x45 into one of my AR's, just see what really would happen

Maddog,

Thanks for the tip on the chamberings.  I was already pondering that.  I am used to sorting rounds and brass, as I have quite a few oddball cartridges.  I thought the 5.56 in the 6x45 chamber would be a fireform round  I would bet that you would have to seat a 6x45 really deep to get it to go into a 5.56 chamber.  Oh wait, that is what the forward assist is for, right?  Nice thing about my QCB system, if I did grab the wrong loads for a trip to the range or a dog town, I could just switch out to the proper barrel, as I usually have the entire system with me.  Plus, I keep a few of every caliber in my case, so my sytem is pretty much grab and go.  The biggest possible snafu for me would be shooting the caliber at the ranch that I frequent.  Everyone else uses 5.56 religiously.  If they were to get a 6x45 case, it could really foul up their reloading.

Thanks for the confirmation on barrel length.  If I go this route, all the information that I can find would be valuable.  It gets a little rough with pressure testing rounds with non-standard chamberings.  A lot of interpolation and extrapolation when you do not have good hard data in reloading books.

I think that I would have to go the 24" route.  I would need every bit of velocity that I could safely muster.  I am still young enough that toting a heavy gun around is no big.  I confirmed that the 85 grain bullet would be legal for antelope in Colorado and NM (NM has very few rules anyway).  The numbers from you and Marty would suggest that the Barnes 85 TSX would stay above the 1600 FPS threshold to at least 500 yards.  It does not have enough energy for my liking for big game killing, but it looks pretty decent out to 200 or 300 yards.   I need to do a comparison to the 5.56 round to see if it offers any advantages in long range PDing.  It's pretty windy out this way during the summer months.

Ah, the Moly mine in Questa.  For the transplanted anglos it is a blight on the face of the earth.  For the locals it has been a source of jobs and income for a lot of years.  Typical politics round here.  I do believe Roberto's is still here.  Been there once, but I had the rellenos.  I am weak for them, as everyone has their own secret recipe, and all are somewhat unique.    If you ever find yourself out this way again, drop me a line, lunch or dinner will be on me.   Tell me what you have a hankering for, and I can find the best spot.  If you have any contacts at the moly mine, some of the largest prairie dog towns out this way are in Questa on private property.  Lots of folks up that way work at the mine.   Being a Land Surveyor, I have been asked to work up there, but have always passed.  Too much experience with big clean-up sites, MSHA and OSHA in my previous Colorado life.

Thanks again,

Craig

Craig,

The 6x45 is not fire formed, you just run it through a sizer die to expand it from .223 to .243.  It really is one of the easiest wildcats you'll ever get into.
The Sierra #V manual has a good number of loads for this cartridge and a nice write up, check them out.
If you'd like, I could fax copies of the data. Shoot me a email.

Jim

Maddog_44 is right.  The Sierra manual as well as many others have quite good coverage of the 6 x 45.  It is very easy to load for, even easier than the .223.

As far as barrel length, I would think the 20" would pretty well max you out for velocity.  I have chamber quite a few in 16" and 20" but have never had the call for anything longer.   Rembember, it has the same case capacity as the .223 but a larger bore capacity to burn the powder in.  I think you would be carrying around an extra 4" for nothing.

The 6mm TCU uses a fire formed blown out shoulder, where the 6mm/223 is a easier resize.  Many years ago there was an article in Shooting times about using the cartridge in a single shot for antelope.  I believe they were using a Nosler bullet around 100 grains.

Email sent

For a midrange (MQB ?) battle rifle IMO the next logical step up from the 223 REM is a 243 / 6 mm class round not the 6.8 as currently designed. The 223 Rem is based on a limited case capacity 22 cal.  size case not like the 22-250 or 220 Swift. The small size means you can carry alot more rounds of 223 REM per weight than 6 mm or 6.8 ammo. The .243 WIN is based on a necked down .308 WIN size case which for me translate to a much higher level of potential performance. A 100 gr. 6 mm bullet can be driven at 62 gr. 223 Rem speeds of 3000 fps. The 6.8 is over matched with it's bullet payload and while better than 223 REM IMO if it were necked down to a 6 mm or even a 25 cal size it would be a much improved round.

None of these cartridges is the best at every thing, just like bullet designs differ to deliver the performance we want on target. You really need to ask yourself what you want a rifle / ammo combination to do. What game is to be taken as well as the expected range to target help to narrow the field.  So far it sounds like the 6x45mm will do what most of you want.

AS far as the 6.8 I think it is best left alone, it just does not offer enough powder capacity to justify
necking it down to .25 or 6mm caliber.  

Joe

Where to start?

Thanks everyone for the suggested manuals.  I have quite a collection but apparently not the right ones.  I will do a lot more checking.

Marty,  email sent.  Your a bad boy......

Maddog, I was just kidding about the fireforming.  I suspected that it should just be a case of expanding for the initial round with a die.  But, there is a certain amount of fireforming that all cartridges go through with an individual chamber.  I like to do my serious load development with once fired rounds and usually just neck sizing.  I know this is a no no for autos, but I have had good luck with 4 or more neck sizes in my 5.56, and many more in my 458.  I guess I am just pretty anal, but I like small groups.  And, I am talking about a hunting round, not life and limb.  I will check into the reloading stuff that I can find, then I may take you up on your offer.  I think I am about 99.9 % on putting this one together.  Thanks.

Dtech,  I am with you on the barrel length, but my goal is to try and get very good velocity, and I want the weight for recoil mitigation.  The sight picture at 15 power is easily lost, and I want this gun to double for prairie dogs.  I would like to not have to brake it, as I sometimes shoot PD's with others, and I have partial hearing loss due to one guys eagerness to kill a dog with his braked gun.  It was not unsafe, just stupid.  My plan is to see where things are at with 24 inches, comparing this to others with 20 inchers.  Then I can decide to trim and/or brake, depending on the results.  Now that I have found some guys actually using this little critter.   There is also the issue that I want to use the Barnes TSX, which (according to Barnes) might need a little more powder to get the pressure back up.  If I start with all of the variables at max, then I can reduce and rearrange to optimize for what I want out of this barrel.  I greatly appreciate your input, as I have seen your thoughts on other boards.  You do know what you are talking about.

TK, yup, I am fairly familar with the TCU stuff, as I was very into Contenders a few years ago.  This is where I ran afoul of this cartridge, as all that I could find was TC data for shorter barrels.  You guys have brought me around on this.  Thanks.

24K, I have been very actively following the 6.5, 6.8 and others debate here.  I have been in need of a midbore since I got into AR's a couple of years ago.  My problem has been that most of the debate hinges on Military performance, and I want hunting performance.  I, like many others, have been slow to jump on the 6.8 for the known issues of brass and parts.  I really like the numbers on the 6.5, but cannot bring myself to buy from a company that will not sell me a barrel and a bolt, as I have a MGI QCB upper.  I am not qualified to address the issues of the 5.56 v 6.8, but I do know that this on going debate and developement has put a lot of other midbore research on back burner.  I think everyone wants to see if and when the Military will make a change or commitment.  At least for me, on the civilain side, with the QCB I can make easy (read cheap) jumps into calibers, especially ones that do not require propriatery bolts and magazines.   I like the looks and performance of both the 6.8 and 6.5, and I pray that our soldiers do end up with the proper choice to save their lives.

Thanks everyone,

Craig

Marty just finished a 6x45 AR upper for me. I've only started load development but using the 80 SSP bullet and H322 it definately looks like it will go under MOA at 100 yards. I still need to get a new trigger installed but hope that will be here in the next week or two. It's a very soft shooting round.

And I can highly recommend Marty, took him a while to find the right barrel but then he had everything together in under a week just as I asked for.

A while back I contacted Sierra about using Hodgdon Benchmark in the 6x45mm with their 85 grain HPBT GameKing bullet #1530. Here is the response.

Benchmark is right between H322 and IMR3031 so I'd start with about 22.0 grains of BenchMark and work up carefully in 3/10ths of a grain increments and I'd expect you to find a max at about 24.0 grains.

JAR,

Thanks, you confirmed what I have queried Marty about.  Benchmark and BLC2 really shine with 75 grainish 5.56 loads, so I guessed that it must work with this one.  If I disremeber correctly, my 55 grain 5.56 loads with Benchmark have a fair amount of case capacity left.  I really like the newer Extreme line of the Hodgdon powder, as they do meter very well, and are temperature insensitive.  Good for me as we can have big changes in temps here in NM.  And you were correct in your previous post, this cartridge sounds like it will work for me.  I am really counting on the Barnes 85 to work.  With regards to the various neckings of the 6.8, it is all about pressure, bolt head size (thrust), and cartridge capacity.  What is pushing me over the top on this is the 5.56 bolt and magazine compatability.  That is worth a few hundred FPS for me.

Browning,

My experience is that the trigger is a large part of those repeatable less than MOA loads, at least for my shooting ability.  They can be done with a lousy trigger, but are so much more work.  You can also easily call fliers with a good trigger.  I've got the Geissele in my lower with the QCB, and love it. Nobody to blame but myself, if you know what I mean.

I have worked with Marty before.  I have one of the first GP 458's, and we have been in touch since.  He's one very class act.  He could turn this alternative caliber AR market on it's ear, if we could figure out a way for him to quit his day job, and not get divorced.  He's a true madman.

Craig

Bearbait, I'm thinking I going to install one of the drop in one piece McCormick triggers and give that a try. They have them on sale for $139 in one of the catalogs and it looks easy enough for even my skill level.

I haven't loaded the cartridge in a while (read decade) but I believe I used to run 21 grns of AA 2460 with a Nosler 100 grn.  I'm sure there are better powder choices now, but almost no recoil out of a 14" XP 100.  I used it for FL deer with good results, but our deer aren't much bigger than a dog with antlers.

If you were running the Contenders, you know they are great little cartridges.  The 6mm PPC or BR will easily outperform them at distance, but then you need more parts.

Randall,

Thank you very much for the data.  I have been following your 6.8 GP, and know how busy you are.  I did find some data for 24" barrel guns, and it does look like I could gain just a bit of velocity with a 24" barrel.  Not tons, but enough the keep a Barnes 85 grainer above the 1600 fps a bit farther.

I really appreciate the Benchmark and Varget modeling, as I have tons of it around for the 5.56, and it does better with heavier 5.56 bullets.

Thanks again, and Merry Christmas

Craig

Quoted: Here is a quickload simulation showing powders that are likely to be found. I'm just learning to use quickload and it's very helpful for choosing a powder. Don't take these loads as recommendations, they are all MAXIMUMS from a computer simulation. Changing the bullet or barrel length changes everything around. If you want to see something specific, just let me know... Cartridge          : 6 x 45 (6-223) Bullet             : .243, 85, Sierra HPBT 1530 Cartridge O.A.L.: 2.250 inch Barrel Length      : 20.0 inch Predicted Data for Indicated Charges of the Following Powders. These calculations refer to your specified settings in QuickLOAD 'Cartridge Dimensions' window. C A U T I O N : any load listed can result in a powder charge that falls below minimum suggested loads or exceeds maximum suggested loads as presented in current handloading manuals. Understand that all of the listed powders can be unsuitable for the given combination of cartridge, bullet and gun. Actual load order can vary, depending upon lot-to-lot powder and component variations. USE ONLY FOR COMPARISON ! Type                     (gr) fill (%) vel (fps) Pmax (psi) Winchester 748 24.8 98 2672 48225 Accurate No.2520 25.1 100 2658 47638 Hodgdon BL-C2 25.2 99 2649 48225 Hodgdon H335 24.2 95 2644 48225 Hodgdon H322 22.4 95 2641 48225 Ramshot TAC 24.2 98 2632 48225 Ramshot X-Terminator 22.6 93 2627 48225 Accurate No.2460 24.3 98 2615 48225 Alliant Reloder-12 23.4 97 2608 48225 Accurate No.2230 23.8 95 2600 48225 Accurate XMR 2015 22.0 100 2597 47676 IMR 3031                     22.5 100 2593 42137 IMR 4198                     19.7 91 2577 48225 Vihtavuori N133 22.3 99 2574 48225 Hodgdon Benchmark 22.5 97 2567 48225 Vihtavuori N130 21.4 94 2563 48225 Hodgdon VARGET 23.7 100 2561 46162 Hodgdon H4895 23.2 99 2537 48225 Hodgdon H4198 19.8 91 2534 48225

Randall:
Thanks for the reloading data for the Sierra 85 grain bullet. Your software is showing about 48,225 PSI as max pressure, this would be lower than the listed 55,000 PSI for this cartridge. Do you think this may be on purpose so they really are well below max to start.

Joe

You guys have convinced me to put one of these together.  I am going to do a 24 inch barrel, so hopefully in the new year we can share some real numbers, and get a little more useable info on this cartridge.  I plan on testing the Barnes 85 extensively, and at least a few other lighter bullets to come up with a good long range varmint load.

You guys are great,  and thanks again for all of your help, and reloading data,

Craig

Quoted: You guys have convinced me to put one of these together.  I am going to do a 24 inch barrel, so hopefully in the new year we can share some real numbers, and get a little more useable info on this cartridge.  I plan on testing the Barnes 85 extensively, and at least a few other lighter bullets to come up with a good long range varmint load. You guys are great,  and thanks again for all of your help, and reloading data, Craig

Craig:
Please do fill us in on how well the 24" barrel works out for you. I have seen the same thing as Dtech as far as my loads with the 20" barrel . Sierra lists load data with their test barrel of 24" and my velocities come close to these with like powder charge weights.

I am glad to see more interest in the 6x45mm, 6mm/223. Good luck with your build and post how well the Barnes 85 grain works.

Joe

Quoted: Craig- Quickload does not have the 85gr barnes, so here is the Sierra...

Randall, which version are you using?  My version gave significantly different results in terms of powders even at the default setting AND it has the Barnes TSX bullets ... got it straight from the man who developed the program, even has dimensioned drawings of the majority of the cartridges.

Quoted: Quoted: Randall, which version are you using?  My version gave significantly different results in terms of powders even at the default setting AND it has the Barnes TSX bullets ... got it straight from the man who developed the program, even has dimensioned drawings of the majority of the cartridges. I have version 3.2, just bought it from NECO a couple weeks ago. How do I go about getting more bullet data? Can you send me your projectile library file? Do you have Quickdesign as well? I can't seem to find a way to view cartridge drawings in mine, but I can create a new design for a cartridge and enter the dimensions to add it to my cartridge library file.

Strange, mine is labeled 3.1 but it is a custom version from Hartmut himself ....

I can see if I can send you the projectile library file.  I dabbled with QuickDesign but found it somewhat counter intuitive.  I have another program that is better for "quick n dirty" designs that gets me close enough to see if a design is worth more work

Here is what I got for the 6 x 45

Cartridge          : 6 x 45 (6-223)
Bullet             : .243, 85, Barnes 'TSX' BT 24341
Cartridge O.A.L. L6: 2.260 inch or 57.40 mm
Barrel Length      : 24.0 inch or 609.6 mm

Predicted Data for Indicated Charges of the Following Powders.

Matching Maximum Pressure: 48225 psi, or 332 MPa

or a maximum loading ratio or filling of 110 %

These calculations refer to your specified settings in QuickLOAD 'Cartridge Dimensions' window.
C A U T I O N : any load listed can result in a powder charge that falls below minimum suggested
loads or exceeds maximum suggested loads as presented in current handloading manuals. Understand
that all of the listed powders can be unsuitable for the given combination of cartridge, bullet
and gun. Actual load order can vary, depending upon lot-to-lot powder and component variations.
USE ONLY FOR COMPARISON !

79 loads produced a Loading Ratio below user-defined minimum of 90%. These powders have been skipped.

Powder type          Filling/Loading Ratio  Charge    Charge   Vel. Prop.Burnt P max  P muzz  B_Time
                                     %     Grains    Gramm   fps     %       psi     psi    ms
---------------------------------  -----------------------------------------------------------------
IMR 3031                           103.5     22.8     1.48    2775    99.4    48225    7039   1.156  ! Near Maximum !
Accurate XMR 2495                  105.0     23.2     1.50    2755    99.8    48225    7003   1.194  ! Near Maximum !
Accurate XMR 4064                  110.0     24.6     1.59    2750    98.5    48057    7255   1.191  ! Near Maximum !
Winchester 748                      97.0     24.1     1.56    2742    96.4    48225    7187   1.161  ! Near Maximum !
Vihtavuori N150                    106.5     24.3     1.58    2735    99.2    48225    6912   1.163  ! Near Maximum !
Accurate No.2520                    99.4     24.4     1.58    2735    97.3    48225    7120   1.175  ! Near Maximum !