How far could you conceivably neck up a 5.56 NATO round by just running it through sizing dies and not splitting the neck etc. 6x45 is the largest wildcat that I know about on this casing. I just had an idea that it would be nice to have all of my rifles based on the same casing.

Also, is there some formula or program that could be used to project velocities and energy levels when you move out of charted territories. I've never had luck with subsonic rounds shooting at game. I've watched crows "jump the bullet" so to speak when shooting subsonic .22LR at them.

There is a group of wildcats that were based on the 223 case that were used for handgun silhouette shooting. Those wildcats were labeled TCU, i.e. 7mm TCU, etc.
The case was necked up to at least 7MM, that I know of.
The TCU wildcats also were an 'improved' type wildcat, to maximize the powder capacity of the relatively small case.

I always thought that a .25 TCU (or .25-223) would be just about ideal as a called-predator round. John Wooters developed the 25 Copperhead, which was the .222 necked up to quarter-bore, and he raved about it for the remainder of his life. With the easier availability of .223 brass - and the slightly larger case volume, I think the .25-223 would be superb.

You can predict lots of ballistic items using commercial software. I use Load From a Disk for Windows by Wayne Blackwell ( www.loadammo.com ). Others use the more flexible but also more expensive QuickLoad.

You can even do a pretty good job with a hand calculator using the Three General Rules of Reloading. I'll post those as a separate thread if you'd like.

If you want an interesting round, how about the 6mm Thermos Bottle, it'll toss a 107gr MK around 3100 fps.

Both the 6x47 and 6x45 are decent little rounds, the 6x35 (shortened .222 case) wasn't much to speak of, not enough room for powder to be effective for anything beyond 100 yds. If you don't want to get into all the hassles of wildcatting, perhaps the 6.5x52R (.25-35 win), ammo & dies readily available - little bigger case and it's rimmed, just a thought.

the 6x35 (shortened .222 case) wasn't much to speak of, not enough room for powder to be effective for anything beyond 100 yds.

I disagree, I think a .221 Fireball necked up to .243 or .257 would be a very useful (and fun) cartridge to have.

I was actually thinking of necking it up enough to toss a 200 grain 8mm or .338 bullet. And if you could, what kind of velocities you would be able to get. I was hoping for about 1,800-2,000 fps or so. Not for varmints or predators, but as a light recoiling round for bigger game based on the same case as my predator rifle.

You can neck the 223 or 222 Remington Magnum all the way up to .357!!!

We do alot of the above listed cases in 7mm T/CU, 30 caliber and 357 for the H&R single shot rifles and have been doing several in 357 for the T/C Contender...

I don't recall as having done one in the 338 or 8mm calibers but it would be a simple chambering, necking and throating operation for whatever caliber you wanted...

Also, it would be wise to anneal the case necks if you are going to go above 7mm just to keep them from splitting....

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You can neck the 223 or 222 Remington Magnum all the way up to .357!!!

We do alot of the above listed cases in 7mm T/CU, 30 caliber and 357 for the H&R single shot rifles and have been doing several in 357 for the T/C Contender...

I don't recall as having done one in the 338 or 8mm calibers but it would be a simple chambering, necking and throating operation for whatever caliber you wanted...

Also, it would be wise to anneal the case necks if you are going to go above 7mm just to keep them from splitting....

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Any idea what kind of max velocities I would be looking at necking up to that range for a 200 grain bullet.

After going through all my recources, with bthe 223 case being necked up to 8mm or 338, it looks like you should be able to push a 200 gr. bullet between 1,800 and 2,000 fps. in a rifle length barrel...

I know from personal experience though that in the 223 necked up to 357, a 200 gr. bullet will easily exceed 2,000 fps. from a carbine length barrel....

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After going through all my recources, with bthe 223 case being necked up to 8mm or 338, it looks like you should be able to push a 200 gr. bullet between 1,800 and 2,000 fps. in a rifle length barrel...

I know from personal experience though that in the 223 necked up to 357, a 200 gr. bullet will easily exceed 2,000 fps. from a carbine length barrel....

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Nice, what is that wildcat called? Also, what does it headspace off of? I'm assuming it's pretty much straight walled at that point, so you can't headspace off of the shoulder. And there is no belt or rim either. So is headspacing basically done by the base sitting on the bolt?

I don't have a name for the 223X357 other than that...

This round headspaces off the case mouth just like what a pistol cartridge does for a semi automatic pistol. ALL cases must be trimmed to the same exact length and they are not crimped. I have only chambered for this round in the T/C Contender and the H&R...

One better yet is what I call the - 357 Super Max. This round is loaded using the 5.6X50R case with the walls blown out straight sided and the case mouth opened to accept a 357 bullet. This long skinny round beats the pants off the 35 Remington with bullet weights up to 200 grains and even with the heavier hard cast bullets, it still beats the old Remington round...

No special dies are needed either as I use a regular set of LEE carbide 357 Mag. / 357 Max. dies to load for the round...

My 357 Super Max is gaining in popularity with the Ruger #3 shooters shooting lightweight 16 1/4" to 18" barrels. The H&R also does well with this cartridge....

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Firstly, assassin, if you don't mind send me a PM with your e-mail or instant messenger. You seem to have a lot of experience with 5.56 and I have some other idea's to run by you. And forums generally aren't the best for 1 on 1 conversations. Also, I plan to use actual military 5.56 brass. So I should be able to safely push pressure levels a little bit higher than with .223 brass. 58,000 CUP as opposed to 50,000 CUP.

I didn't realize that auto's headspaced off of the case mouth. But I do not want to move off of the 5.56x45mm.

So you get an idea of the bigger picture, I'm going to quote myself from another forum.

I was thinking of a full length barrel 20"-22" with a target velocity of 2,000 fps for 200 grain bullets. Hopefully that will have enough enertia to penetrate both lungs on an elk assuming broadside shots inside 100 to 150 yards.

At risk of sounding like a paranoid schizophrenic, and to put it all in perspective. I basically want to have 3 rifles of 3 different calibers to cover everything I could possibly hunt, all based on 5.56x45 brass. That way when the zombie's attack or the global economic platform collapses or we get struck by a massive asteroid I can roll my own ammo and survive. Using what will probably be the most widely available salvageable brass, with an efficient powder to shot ratio. Maybe I should also say that sense I live near and have access to a military base, I can collect expended brass from the ranges on post. So I am talking about thick military 5.56x45mm NATO brass.

I had thought of 7.62, but the powder volume is a lot higher. And the brass less abundant on said ranges.

For one thing, THICK MILITARY BRASS will be a problem because of the decreased powder capacity and for reasons of safety, I would NOT load to 58,000 psi and would stay withing the s.a.a.m.i. spec for commercial 223 ammo!!!

Also, the thicker military 223 brass does not lend itself well to that much neck expansion without the necks splitting. Plus the fact that with the decreased powder capacity, you might NOT be able to reach your desired velocity level...

I know that it's not as "cheap" but for wildcatting, stay with the better brass like Winchester or move on up to something like Lapua or Norma....

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One better yet is what I call the - 357 Super Max. This round is loaded using the 5.6X50R case with the walls blown out straight sided and the case mouth opened to accept a 357 bullet. This long skinny round beats the pants off the 35 Remington with bullet weights up to 200 grains and even with the heavier hard cast bullets, it still beats the old Remington round...

No special dies are needed either as I use a regular set of LEE carbide 357 Mag. / 357 Max. dies to load for the round...

My 357 Super Max is gaining in popularity with the Ruger #3 shooters shooting lightweight 16 1/4" to 18" barrels. The H&R also does well with this cartridge....

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4 or 5 years ago, maybe, I made a tapered expander for one of the forum moderators (Contender) who was doing just such a project for a T/C - if my memory is correct.

I don't recall how it turned out, exactly, other than some vague recollection that he deemed it a success. It was, to the best of my memory, the 5.6x50 R (or some other rimmed European case of approximately that size) case necked up to .35 cal.

Just shows great minds think alike!!! :D

MikeG,

it would be interesting to hear the results of what someone else has done with the "357 Super Max" as I have not yet found anyone else out there who has done such a chambering! Do you remember if he left the case full length?

I'm compiling a list of loading data for this round and keeping track of the barrel lengths and velocity gained from each barrel/gun and hopefully I can offer a complete list of information with bullet weights from 125 gr. to over 250 grains, twist rates, etc.. Should prove quite interesting....

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Dunno, but you should be able to email him through the forum. That might be best.

Assassin

Re your .357 Super Max ( 9*50 Rimmed ).

Are there any problems with extraction of this now straight walled case from the G2 Contender? I have been thinking along those lines for some time.

Bones

Assassin

Re your .357 Super Max ( 9*50 Rimmed ).

Are there any problems with extraction of this now straight walled case from the G2 Contender? I have been thinking along those lines for some time.

Bones


Bones,

I have not experienced any problems at all, even though I have only done this in the regular Contender and not the G2. Unless one is loading "HOT", there should be no extraction problems....

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