Have long wanted to build a rifle in this class.
Walking Varminter type Rifle for Fox,Coyote & Chucks in populated area. 200-250 yds.
Both cartriges are very simular 6mm bullet on .223 case. As best I can tell the TCU is more-less an Akley Improved version.
I can find almost nothing on the 6X45 and everything I have found on the TCU is in 10-14" barrels. This makes it nearly impossible to decide which would be a better choice.
What would be the advantages-Disadvantages of either choice? What could one expect in Velocity & accuracy?

I believe that you are correct in your analysis. My understanding is that the 6x45 is simply a necked up .223 case that maintains the same shoulder angle and location. The 6 TCU fireformed into a chamber that has a 40 degree shoulder that gives a little more powder capacity. I don't think there would be a spit's worth of difference if you're talking about ranges under 250 yards. Obviously with more powder capacity comes more velocity so the edge would go to the TCU. All the data that I have seen has been for a 14" Contender as well for the TCU. I suspect that you could gain between 300-350fps over the listed velocities for a 14" barrel (depending on the rifle barrel length).

Thanks for your response. I think so long as I am going to venture into the Wildcat arena I might as well go with the TCU and learn to fireform cases as well. I think 3000fps is possible with 60 grn bullets and a 24" barrel.
Will start looking for an action.

I've had both and really side with the 6mm-.223 (6x45) for your purposes. The TCU was developed primarily for the Contender as the nearly straight-walled approach often gives better performance (I won't get into the details of that here, though) in the break-opens.

I must disagree with the other post, though: you'll only gain 100-175 fps when going from a 14" barrel to one of 24", and more than likely, 100-125 fps is about all the difference you'll realize. That's because this is a very efficient cartridge.

My XP 6mm-.223 with a 14" Shilen does 2740 fps with the 80 grain Sierra SP/SSP. You'll be hard-pressed to reach or top 2900 fps with a 24" tube. My 15" Contender barrel from VVCG isn't quite as swift but still manages around 2650 fps with 80 grainers.

Also, after firing many thousands of rounds in the 6x45s and other wildcats based on the .223 case, I can tell you that I have used more H-335 than all other powders combined. The blend of accuracy and velocity afforded by H335 is simply difficult to improve upon.

And, the Rem 7 1/2s are what I prefer in a primer. Lastly, avoid the nickel-plated cases and start with new, commercial brass.

B-Koes-
I recommended the 6x45 because of its simplicity. Run the case through a full-length die and load -- with no fireforming necessary.

Also, the TCU requires extra-careful loading techniques; otherwise, you can ruin the accuracy via improper sizing. This is no problem for one familiar with these cartridges, but I've seen too many TCU shooters give up on a barrel because of a lack of understanding of proper sizing/loading techniques.

Also, given equal pressures, the velocity spread from a 14 to a 24" barrel in my testing has never approached or exceeded 300 fps -- and this is from actual shooting, not interpolation of data. There have been certain loads in which there are differences in the 200 fps range, but more often than not, 150 fps is the top-range norm, expecially with the bullet weights I generally use (70-85 grains).

As I said, my 14" XP does 2740 fps with an 80 grain Sierra SSP. Most 24" barrels won't get beyond 2850 fps within the same pressure limitations. Granted, that Shilen is a little fast, and a 15" VVCG tube I have doesn't get quite 2700 fps. But there will be variances among the rifle barrels as well.

A perfect example of that is a bull-barreled rifle I had. It wore a 20" SS Hart barrel. With 80 grain bullets, it was a one-hole grouper all day long. But the MV never exceeded what the 14" XP would do.

This is all very interesting. I had not considered the problem of magazine feeding.
I have been shooting a Savage 10FP in .223 and have been loading single shot.
There is merit in the 6X45 being much easier to form. Velocity is not a big issue out to 250-300 yds, a critter shot at 2700 vs 2800 would`nt notice the difference.
I would likely use this on paper as well at 200 yds so have discovered that Brass prep is a time consuming issue. Thanks for your input!

I have dont have tht 6's but I have a 257 TCU in a T/C and a 25/223 Harrison Imp in a SAKO L491. I dont see much gain in Vel when going to a 24"barrel. One thing that I have to do is seat the bullet deeper for the SAKO for it to fit and feed in the mag.

THSimpson

Jim, I guess I'm "muddying the waters" some , but the 6X47 (222 Rem Mag necked up to 6mm) might also be something to consider. I believe it was once quite popular w/ the benchrest crowd before the advent of the 6 PPC so it's got to be very accurate. Of course, 222 Rem Mag brass is not as readily available or as inexpensive as is 223 Rem brass. On the other hand, you'd probably gain a little velocity over the 6X45. Max velocities from "Hornday Handbook, 5th Ed." (27" barrel) are as follows: 58 gr bullet-3500 fps; 65 gr bullet-3300 fps; 70 gr bullet-3200 fps; 75 gr bullet-3000 fps; 87 gr bullet-2800 fps. If you wanted to go the "improved" route, you could get a 6X47 AI, as well. Gary T.

Search the reloading forum for 6x47, I very nearly went this way and got a lot of data on it before I decided that it wouldn't work for me.

I have in front of me the Nov 99 Man Magnum article by Gregor Woods on the 6x45 velocities from readers rifles (no barrel lengths but all for hunting so likely no more than 24")

60gr 3200
75gr 2620
87gr 2600
100gr RN 2400

Gregor's use of the rifle was for deer so velocity was not paramount. I myself used 55gr at 3,250fps in my short 243 and it was very good on foxes out to 200yards (the longest I tried it)

1894

My 6x45 has a 22 inch barrel with a 1 in 10" twist and I match the speeds published in the Magnum magazine of Nov 99.

From what I have read, you guys have faster burning powders, so should be able to improve on the velocity - but for what purpose?

Recoil is neglible and the rifle is VERY accurate. Reloading equipment and components are easily obtainable.

My loads are tailored to my hunting requirements. To limit meat damage (we have to pay for the animals we hunt) I use a 100gr Hornady Round Nose at � 2300f/sec for short range work (less than 150m) and 87 gr Hornady SP and V-Max for longer shots. My loads have been tailored to have the same point of impact at 100m - so that I do not have to rezero my scope.

As I have no first hand knowledge of the other calibres mentioned in this thread, I cannot speculate if the 6x45 is better, or not.

Johan

I have a 6TCU that Bullberry rebarreled for me from a Win 70 LW 223. It has a 20" barrel and I get 3200fps w/60gr HP, 3100fps w/70gr, and 2950fps w/80gr Hor SS SP bullets. It has a 12" twist so any bullet over 80gr is a waste. The chamber was cut minimum so all I had to do was expand the 223 cases to 6mm in the FL die and fireform w/a starting load. I only neck size and all my cases have been loaded over 10 times each and have not lost a case to firering. The 6TCU case is almost the same capacity as a 6PPC and the data for my gun runs close to 6PPC balistics.

I have been shooting the 6x45 for years in a custom lightweight hunting rifle..L461 Sako action, douglas barrel and a beatiful dark red fiddle back piece of claro walnut that was as hard as woodpecker lips...Weighs 5 lbs and will shoot a 10 shot .400 group from time to time and always near a half inch...

H335 and H322 or the powders of choice. 20" barrel
IMI brass, Fed. Brass and CCI400 and Fed 205M

60 gr. Sierra 25 grs H-322 3100 FPS
75 Gr. BarnesX 26 grs. H-322 2944 FPS deer
70 gr. Nos.Bal.tip 27.5 H-322 3096 Acc.@.347
75 gr. Nosler 28.5 H-335 3200acc.@.460
55 gr. NosBaltip 25. H-322 Best Acc@.265

These are my best loads for my rifle out of hundreds tried..some are max so work up to them.

I have shot a lot of big game with the 75 gr. BarnesX and it is the only bullet that has worked well on big game...shoots about an inch...I would like to try some of GS HV bullets in it...I have gotten two exit holes with the BarnesX on several ocassions and that must be petals comming off...or perhaps bone fragmentation.

I had my 6x45 built as a small game / short range rifle, hence I load a 100gr Hornady RN at 2300f/sec. To extend it's range I also load Hornady 87gr bullets at 2600f/sec.

Last week I took the son of a friend on his first hunting trip to Namibia. I normally hunt with a 303 Brit but the recoil is a bit heavy for the 12 year old, lightly built boy, so I took the 6x45 with as well.

The rifle accounted for 6 springbuck on the trip. 4 at ranges of 250 to 300m, 1 at �40m and one at �60m. The smallest springbuck had a nett carcass weight of 23kg. Craig's first springbuck had horns of 13".

He also had a very good time shooting ground squirrels vir 87gr V-Max'es at 100 to 150m.

As stated before, the 6x45 is easy to reload, with easily obtained components, has low recoil and is very accurate.

Johan