The 223 Short project.

[briannmilewis]

Bob:

Thanks for the valuable and detailed input. One of the reasons I throw these things out for comment and review, is I know there are folks that have been there and done that on GBO.

Based on your and other input about minimal neck length, the next chambering will use a 222 Rem neck spec., here are both current and future case drawings.



As always, I appreciate your input, it will help make the project a success.

Contrary to the above description of 223 Short Part 2, through more recent research on my part, we by chance almost hit the optimal length from base to start of shoulder (Case length x 0.7072). I originally specified the case to be 1.125" max. Jed made up the first batch of dummies for the reamer design at 1.135" max.

In a later version of the 223 Short, after we test the current design thoroughly, I will make what you would call a "Bench Rest" version. It will have a 30 degree shoulder angle, that starts at .803" from the base of the case, and have a .008" or .011" case taper.

These three attributes are based on the common Remington and PPC benchrest designs, a smart place to start I think. Case diameter, and length of neck and shoulder do not seem to be critical in the short BR cartridges. I will accept whatever results from the three BR attributes specified for the 223 Short. I know if I had the software, I could know what the shoulder and neck lengths will be ahead of time. Shane, can you run it up the software flagpole when you get a chance?

I do not know if the taper should be proportional or absolute compared to the popular BR cases. Absolute is 0.011", proportional based on case length would be .008" taper.

Another similar round with less case capacity is the 5.7x28 FN, the ballistic equivalent of the 22 Hornet (150yds), which is 75 yards short of our design goal of 225yds. The differences are it has a case length of 1.138", zero taper, and a 35 degree shoulder that starts at 0.9114" from the base. It is optimized for semi-auto use, we plan on bolt-action and single-shot use.

Thanks for everyone's continued interest, I think Spring will be seminal for the 223 Short project thanks to Jed, Larry and Shane.



Cartridge drawings are derived from those available on Steve's Pages. One of these days I will be able to make a donation to GBO and Steve as well.
http://www.stevespages.com/page8d.htm

[chipsoles]

Hi Brian, & Crew,
 With the dims. given in the last dwg., the neck length, would end up @ .235". This combination, should help to reach your goal. Has anyone decided if ID reaming, or neck turning, will give the best results, balanced with ease
of processing?
 I would like to wish all of you, a safe, holiday season.
Bob

[briannmilewis]

Hi Brian, & Crew,
 With the dims. given in the last dwg., the neck length, would end up @ .235". This combination, should help to reach your goal. Has anyone decided if ID reaming, or neck turning, will give the best results, balanced with ease
of processing?
 I would like to wish all of you, a safe, holiday season.
Bob

Thanks Chip (<-- I am assuming that): Everything helps. We are sticking with the original chambering, except on mine, Larry will size the chamber neck for the 221 FB case OD thickness.

[chipsoles]

Brian, Have you looked at 9mm Win. Mag. brass, for your project? The head dia. is .394"+.016"
with a length of 1.160". Just a thought.
Bob

[briannmilewis]

Bob, just looked at a drawing...maybe too difficult to get the neck down completed without a pre-existing shoulder and neck...would be about the same as necking down the 357 mag to the 256 Win Mag and one step further...not always easy and may need one or two interim steps to make sure the brass is preserved...starting with 256 Win mag as a basis of a rimmed version might make sense.

[briannmilewis]

Looked at a number of web postings and checked with Larry, trying to make a final decision on what I will use as platform for my 223 Short testing. Cash is/will likelybe tight, I have decided to go with either a standalone Rossi (non-Wizard) 12 gauge for the stub, or a Rossi 12g from a matched pair - 12g and 223. While there is no official Rossi line on this, Rossi forum folks have measured the barrel swell on rimfire/410 pairs, 357 s and the centerfires and 12 gauges. It appears the barrel swell and matching receiver is the same dimensions for the 12g and the centerfires, which would be SB2 in Handi parlance. The 410s and 357 use narrower barrels and receivers and would be SB1s in Handi speak.

My err on the side of caution would be to buy a matched pair 12g/223 so there would be zero doubt about the 223 Short being safe. If I want to take a risk, I may just buy a 12g and ship Larry the barrel, and then take some prudent precautions like an 8ft string on the trigger, gun in a rest and hiding behind a tree. Larry put a 22 Hornet successfully on a Rossi 22/410 frame, and while the Hornet does not have the pressures of a 223, it certainly exceeds the average shotgun with a much smaller bearing surface. Also, I guess their Rossi shotguns don't use large firing pins.

Now if cash is not a barrier, the next level up I would do would be a Rossi Wizard and 12g for the stub. The Wizard only has one receiver that fits all barrels. Or could likely rechamber a Savage Axis for the same amount.

[Bull45cal]

Go Axis and don't look back.  I talked to Savage tech support the other day, and all you need for a .223 to .22-250 swap is a new bolt head assembly (disassemble the bolt and swap head assemblies), new .22-250 mag, and a new barrel.  (depending on your confidence in your abilities or available funds, you might want a "Go" guage for each of the calibers you purchase) 22-250 barrel pre-chambered and threaded (ready to go) from ER Shaw for $180 shipped.  Bolt head assembly for $50-60.  Mag for $30.  Once you have the bolt head, all you need is the barrels, and mags, then you can have 243, 308, 270, 35 Whelen, etc......  You will also need the barrel nut wrench and action vise which are one time cost items.  Look, I'll even make the action vise for you if you need.  It's not hard.  You'll love yourself for it later.   

[briannmilewis]

Last week I gave LarryT the go ahead to make the 223 Short barrel for a Savage. So I am taking Shane's advice and will be getting an Axis or a Stephens 200 to keep within a tight budget. I am first going to try used and then if the price is close go new.

I am also going to get a smith to swap the barrel, or I may be game enough to do it myself after reading a really good write up in Shooting Times about swapping Savage barrels. Larry and Shane are always available for reference and support if I do it myself.

I will be shooting 35gr - 46gr bullets for my testing, and likely using L'il Gun powder to begin, and Remington Benchrest small rifle primers, they worked really well on my Hornet.

The final performance I will be looking for is Max Point Blank Range of 225 yards, no more than +/- 1.5". If I can find that sweet spot, I will be done and it will be a modern alternative to the 22 Rem Jet and 218 Bee. After discussion with Shane we will NOT apply any case dimension changes unless we can't meet the performance goal. In Shane's opinion there is too little powder in the Short to make any case changes significantly effect the performance.

When the 223 Short is done, we are already kicking around other ideas that have been brewing while the 223 Short takes its course.

Later folks.

[briannmilewis]

Based on recent email swaps with Shane, I think it is a good time to review my design goals for the 223 Short, and see how the little round stacks up to our expectations.

225 Yard Coyote Getter - Shane's testing has shown varmint accuracy is good to 300 yards. √

Cheap Parent Cases - Shane's testing has shown that mixed headstamp 223 Rem make fine 223 Short cases with minimal to no loss during forming, and no significant difference in accuracy between brands. (221 cases necks are significantly smaller OD and had to be specially handled when resizing fired brass, so they do not meet my criteria for simple/easy forming.) √

Simple Forming - Forming the cases is achieved on basic loading presses, not requiring heavy duty presses. Here is a quote from Shane about the difference in forming cases from 223 Rem and 221 FB:

After fire forming and resizing, the 223 Short brass formed from 221 brass has a smaller outer neck diameter than that formed from 223 brass.  The brass that makes up the neck (of the 223 Short) comes from the middle of the case body (thicker brass), when using 223 parent brass.  When using 221 FB parent brass, the brass that makes up the neck (of the 223 Short) comes from the shoulder area (thinner brass).  That is why I had problems sizing 221 FB brass and 223 brass with the same mandrel.  I ordered two more mandrels from Lee.  One was .001 smaller than original, and the other was .002 smaller. √

Small Powder Usage - Shane's use of L'il Gun shows powder use the same as the 22 Hornet (14gr max). Have been reading up on Blue Dot, and it may give us less powder use than L'il Gun and up the velocity past L'iL gun. That maybe the way I get my 225 yd +/_ 1.5" trajectory. √

Performance to match 218 Bee & 22 Rem Jet - Shane's testing confirms that the cartridge has much more performance than the two older style cartridges, we are encroaching on the 221 FB performance. √

Accuracy - Shane has experienced some brilliant accuracy from 50 yards to 300 yards. I was hoping for MOA, reality is MOA or better. Some like a 50 yard group with 8 rounds in one hole and 1/4" flier on the 9th shot, then 3/4" to 1-3/4" groups at 300 yards! Shane's rig has something to do with that I am sure. My rifle will be a shop bought Savage or Stevens.

Trajectory - I am looking for a MPBR of 225 yards, with +/_  1.5". I will have a better chance of meeting that using much lighter bullets than Shane. √

While I still have to test the lighter bullets in a production rifle, and Shane is chasing optimal loads, it is obvious that we have met or exceeded my design goals. That is directly attributable to Larry, Jed and Shane's contributions to the project, they really know what they are doing.

I expect all data to be in by Fall, so we can present a finished round knowing exactly how much it costs to rechamber a rifle and reload this puppy.

We will post more shooting results and pictures, we need pictures of target and the rifle.

Thanks for following us so far, and we hope you stay with us to the end of the project.

Again, I am so grateful to the GBO family who have helped us along the way with comments, questions and suggestions. The four of us on the project are more than happy to share our findings of what went into the project at every stage. Hopefully, when we are done, some of you will want to try the cartridge and we will assist in any way we can.

Brian

[briannmilewis]

Bullet and powder selection for the lighter bullet testing.

The range of bullets is 35gr - 46gr, and I need to select bullets from the following pool:

Hornady: 35gr NTX; 35gr V-Max

Barnes: 36gr FRAN Var-Grenade

Berger: 40gr HPFB (Varmint)

Hornady: 40gr V-Max;

Nosler: 40gr Spitzer Ballistic Tip

Sierra: 40gr BK-Moly; 40gr Blitzking; 40gr HP Varminter

Speer: 40gr SP Spire Pt; 43gr TNT-HP Green

Barnes: 45gr BT Banded; 45gr TSX Trip-Shok-FB

Hornady: 45gr Hornet; 45gr HP Bee

Remington: 45gr HP

Sierra: 45gr SPT Varminter

Speer: 45gr SPTZ Spitzer

Speer: 46gr FNSP w/Cann

Winchester: 46gr HP

I am not going to use roll my own bullets to keep the evaluation task relatively simple, and help out folks that do not cast their own. Of course if anyone wants to build a 223 Short and try casts and provide us the test data, that would be welcome.

Powders: L'il Gun, Benchmark and Blue Dot. Shane has coaxed speed and great accuracy out of L'il Gun. He has squeezed amazing accuracy slower using Benchmark. I have recently been researching Blue Dot in 223 Rem cases and people are having great speed and accuracy, so I think is is worth a try in the Short.

Cases:

I am going to try mil surp that have been processed.

I have an observation about the accuracy and performance Shane saw last season. As the round unexpectedly behaves more like a 221 FB than the 218 Bee and 22 Rem Jet that it was designed to replace, I think the case design may have something to do with it, as well as the L'il Gun powder. Some of you know that I have spent a lot of time looking at the Bench Rest cartridges and came to the conclusion that they are of a particular length 1.52" or so, and they have a 30 degree shoulder, and the shoulder starts at 1.075" from the base of the case, and they use small rifle primers and flash holes.

By chance, the Shorts shoulder starts at .806" from the base, if BR specs were applied, than the shoulder would start at .803" from the base. So just by chance we hit one of the BR specs. Also, the folks that know BR cartridges (www.6mmbr.com) assign the small rifle primer and flash hole as major contributor to the accuracy of the 6mm PPC, but they do not know exactly how or why.

[geezerbiker]

Dumb question, could .357 mag cases be used to make a rimmed version for a Martini rifle?  I think this would be a killer round for these old guns...

Tony

[Trans.Man]

Amazing Wildcat Project (Exciting)... Surprised this cartridge didn't evolve years ago (the common .223 cartridge [1964], converted into a short version - Reloaders Dream).  Whatever happened to the Colt MARS project (MINSAS)? Abandoned!

I've been researching PDW (Personal Defense Weapons / Calibers) FN Herstal's 5.7x28mm, and H&K's 4.6x30mm. This wildcat cartridge (.223 Short) would be better than either as PDW - IMO.  The FN Five-SeveN Pistol would be an incredible PDW in .223 Short (nearly the same specs as the 5.7x28mm).  It appears very close to being compatible with the Five-SeveN Design (Magazine, Ejector Window, etc.). It would need a custom barrel and some fine tuning. I wonder how much "time" before someone will attempt such a Mod.

By 2009, The FN Herstal Five-SeveN PD Pistol was being used in 40 Nations (Military & Police Agencies), and in the USA, is currently being used by over 300 Law Enforcement Agencies - including the Secret Service.  The Five-SeveN looks real nice, but uses a Proprietary/Unique Cartridge = More Expensive $$$

This .223 Short could become a great dual purpose cartridge (Small Rifle and PD Pistol)... very compatible and cheap for reloaders, very accurate, lower recoil than 9mm, 20 and 30 round clips - for the Pistol.  The case length may need to stay close to 28mm - overall cartridge length to under 41mm to fit magazines inside a Pistol Grip.  WOW - what a fun cartridge this .223-short could be.

Great work and dedication to "The Team".  Thank You

John

Five-SeveN (FN Herstal) (with 20 Round Clip) http://en.wikipedia.org/wiki/File:Five-seveN_USG.jpg
                                                                 http://en.wikipedia.org/wiki/FN_Five-seven

[briannmilewis]

John:


You are way ahead of me mate. Never even occurred to me, but I think that is a symptom of being too close to the project.

I still haven't got the cash together to test the lighter bullets yet. I also have not checked in with Shane this season to see if he has anymore testing to report.

According to Wiki we are exactly the same dimensions overall 28.83mm and case only 1.135" as the 5.7x28.


Why not just take the 22 rem jet (cheap from prvi), put 30 deg shoulder on it that starts .911" from the base? That would be a new 22 revolver round or a modified 357 desert eagle!




Considering Shane has got brilliant performance for 300 yards out of his rifle, in a pistol it would be brilliant because it can use much heavier bullets compared to the 5.7x28, due to the greater powder capacity of a .376" diameter case to the 5.7x28s .313" diameter, and also use the same light bullets too! The 5.7x28 uses about 14gr of powder and the 223 uses the same amount or up to 3gr more, but for some reason burns it much more efficiently so you can get quite unexpected performance form it.   

Any brass manufacturer could pump out 223 Shorts with only a few modifications I bet. I ought to look into that. Maybe we should get it tested in both rifle and pistol, I think you are onto something.

I appreciate your insight. Well, I found Shane on GBO and he offered up his 223 Savage target rig for a 223 Short barrel reamed by our smithing guru Larry T, and signed up for testing. I wonder if I could do a shout out on GBO or Reloaderz and find someone who would be willing to have it done, just the same way Shane came into the project.

OK, the 5.7x28 operates at max 55k psi, the 221 FB runs 46k to 52k. I am sure the 223 Short is in that range too, but I do not have the tools to estimate the 223 Short chamber pressure.


If we had to modify a 5.7x28 pistol to accept the .376 diameter case and larger case head, would that threaten to fail due to chamber pressure, having to remove to much metal from the chamber, unless a new chamber can be made of stronger metal?


If we modified a 223 AR with a 223 Short barrel, that would be very interesting. Are there any 221 Rem ARs? Hmmm, I will research this.

[briannmilewis]

Dumb question, could .357 mag cases be used to make a rimmed version for a Martini rifle?  I think this would be a killer round for these old guns...

Tony

I have been thinking of using the 22 Rem Jet case, already a 357 mag necked down to 22cal. They are cheap from Privi. I would put a 30 degree shoulder on it that starts 0.911" from the base.

[geezerbiker]

I have been thinking of using the 22 Rem Jet case, already a 357 mag necked down to 22cal. They are cheap from Privi. I would put a 30 degree shoulder on it that starts 0.911" from the base.

I'd really like to see how this works out.  I'm really looking forward to getting the Martini fixed and I'm holding off until I can afford to install a new barrel at the same time...

Tony

[briannmilewis]

Had an email exchange with another GBO member about location of shoulder, neck lengths and shoulder angle. We will do a 223 Short v2 that uses a 40 deg shoulder, leaving the neck length a little longer. It seems that shoulder angle focuses the charge and 40 deg is pretty much the perfect focus. Also, reducing charges for the slightly reduced case capacity if the shoulder is changed, should result in more complete burning inside the case, less barrel combustion, maybe 3% increase in velocity.


I would like to do a rimmed version too, so applying the same specs to 22 Rem Jet cases would be pretty much ideal. Would be a good candidate for a 22 Hornet Handi rechamber, using slightly heavier bullets than the Hornet seated out a little further to take up the .103" freebore difference with the Hornet. Should be interesting.

[briannmilewis]

Shane has been laid up for a few months due to a motorcycle accident, so we have not had any ongoing testing this season yet. I was worried so I tracked him down on the web, and called him, we had never spoken before, even though we have been on the project for ages. Same is still true for Larry and Jed, I have never spoken to them either. It is amazing what can be accomplished using the web, doesn't matter if your group is around the corner, across the country, or all over the world.


My guess is that final v1 evaluation will take place in Spring 2012. Sorry about that, I know it is not what everyone hoped, but it is the best we could do under the circumstances and without hard deadlines.


Shane spoke of an interest he has in developing a 223 Short sub-sonic that could be suppressed. He thinks a 90g+ bullet may be able to accomplish that. Gets more interesting all the time.


Hopefully my 1:12 twist barrel will be chambered by Larry soon, and I will be able to follow that up with a Non-Accutrigger Savage or Stevens 223 to fit it too. The reason to fit it to a non-adjustable trigger means that what ever accuracy I get out of it, anyone with a heavier barrel, or Accustock could do better.   

[rayv]

What an interesting thread, and great documentation of how to approach wildcat design.  Thanks!  Very sorry to hear Shane was hurt; hope recovery is going well. 
I found this thread by initially searching on .20 wildcats, and then sort of second-order linking through to this one.  Has anyone considered a .20 version of the .223 Short?  I ask because I'm interested in the .20 VarTarg, but I like the idea of using (i.e. buying) .223 brass a lot more than buying .221 Fireball brass.  :-)

[tacklebury]

Any of you heard of the .22 TCM Auto?  Seems as someone may have beat you to punch on this.  There are already some firearms being chambered in it.  It appears to blow the socks off the 5.7x28.  Article available in the Latest American Handgunner Digital edition.  Not sure if this link will work...:
http://fmgpublications.ipaperus.com/FMGPublications/AmericanHandgunner/AHJF12/

[briannmilewis]

Empty by design...the ammo guide data was for the Reed Express not the micro-mag

[briannmilewis]

What an interesting thread, and great documentation of how to approach wildcat design.  Thanks!  Very sorry to hear Shane was hurt; hope recovery is going well. 
I found this thread by initially searching on .20 wildcats, and then sort of second-order linking through to this one.  Has anyone considered a .20 version of the .223 Short?  I ask because I'm interested in the .20 VarTarg, but I like the idea of using (i.e. buying) .223 brass a lot more than buying .221 Fireball brass.  :-)

We would all be poor if we had to buy 221 FB brass all the time. I feel your pain. Once we are done with the 224 version testing, I really think there is an application for 20 cal and 17 cal versions, especially as we blew the doors off our own performance expectations right out of the gate with the short.

Thanks for the compliments on our process. I designed it, Jed M engineered the dies, Larry T made the chamber reamer, and Shane H donated the barrel and testing so far. I deliberately wanted to design a case that was a modern design and cheap for anyone to make (most abundant brass is 223 Rem), no neck turning or reaming etc, the only thing after forming is to cut that long neck off and chamfer and deburr. We kept the neck at 23º so forming would be easy too. The over arching design goal was "cheap to shoot". I got into centerfire with a 22 Hornet, so that got me hooked on small efficient centerfire cartridges.

[rayv]

Isn't it great to "blow the doors off (y)our own performance expectations"?  I like the way it serendipitously comes so close to the magic BR measurement ratios. 
 
Design criteria of cheap to shoot, easy to form, no neck turning/reaming required (!) .... Like Hannibal said, I love it when a plan comes together.  I have a K-Hornet, and like you, that has sparked my interest in small, highly efficient, cartridges.  This kind of performance on such a small amount of powder?  Wow.  I Really want to see what the (possible) .20 caliber could do.  And the 30 degree shoulder looks like an interesting possibility, too. 
 
Well thought out, well executed by a diverse group.  Imagine what it would've taken to coordinate and accomplish all this without the net.  Ouch. 
 
Looking forward to the next development.   Developments .... :-)

[tacklebury]

The cartridges are quite different, and I expect the 22 Micro-Mag out of a 22" rifle barrel, will not be a 300 yard coyote killer, unlike the 223 Short.

Great find on the web by the way.

Well I was looking at his speeds of 2065 from a 4" barrel and at an average of 50fps per inch of barrel, you get 18*50 fps increase for a total of 2956 fps.  This adds 156 fps to your 2800 fps load.  I am not a ballistician, but just figured I'd put this out there for you to take a look at.    I like the idea of the .223 short for my own reasons, albeit I'm heading in a different direction than massive speed for varmints.   

[briannmilewis]

Good thoughts tackleberry. What I should do is go back to the source and ask them if they have chambered a rifle for it and what the performance is like. I'll report back.

[briannmilewis]

rayv - Without the net it would not have been practical. I had learned in high tech software testing and development how to use the web for projects. I just did a different kind of project the same way, this involved releasing 42 year old master tapes of a famous Australian band of many years ago. Same thing, we are almost at release and I have never met or talked to anyone on the project.

My approach to the design and cheap parent cases etc. played into getting the best result for the least amount of money. We had our naysayers in the beginning who projected (and from past history was the accepted thinking) that we would spend a bunch of money and come up with nothing that some other cartridge already does. Well we spent very little, maybe $300 includes the barrel, the dies, and Larry's reamer. There was more time than money expended which I expected, and once Jed M modified a set of 221 FB Lee Dies, and expeirmented with the best way to form the cases without loss, and we overcame the kneejerk reaction to want to turn and ream necks, then the rest is just been hard work for Shane.

The only expensive part of this is the dies, as I do not expect anyone to make or modify their own. Just trying to work out what the minimum die set would work.

[rayv]

Happy New Year, Brian and the rest of the development crew. 
   I hope 2012 is off to a great start for everyone. 
   Rog on how the web makes such distributed projects workable.  I hadn't considered the intercontinental aspect of it until you mentioned Australia .... but as long as the other person has internet access, that's immaterial, isn't it?  Now, if we could just move solid objects that easily and rapidly.  Scotty, beam this over there .... :-).  I'm glad your project development expertise translated so well to this one. 
   Any new developments on the .223 Short?  Do you guys have any idea what/when the next milestone might be?  Not trying to be a pest; just very interested. 
 

[briannmilewis]

I have to get a barrel from Larry, and then get a Savage or Stevens to go with it and test the 35g-46 bullets.

My ballistic goal is 1.5" above and below line of sight to 300 yards.

We can't appear to do that with the heavy bullets Shane has been testing, he is getting about 3" above and below, the usual acceptable point blank performance from the larger diameter bullets.

I am sure we can get what I want with the lighter bullets.

I hope my money drought is cured by my music project so I can roll into Spring and buy whatever rifle I want the new barrel fitted to and have someone else do the fitting.

That's about all for now.

[briannmilewis]

Brian Note: I had to rework the Bolt Thrust Calculations here to make sure they were correct, they were not.
-----
Nothing yet about light bullet testing.

Just had a chat buddy (Torp) ask me tonight if we could re-chamber a Martini 22LR for 223 Short.

I thought about it, and then read about it, then converted 303 Savage pressures (The Martini uses Brit 303 bolt and I assume outside chamber diameters) to PSI and came up with 37,000 PSI. The Martini case head is 0.166 Square Inches, and the 223 Short case head is 0.112 Square Inches and 55,000psi.

223 Short BT = 55,000 x ((.378 x .378) x 0.7852) = 7858 ft/lb

303 Brit BT = 49,000 x ((.460 x .460) x 0.7852) = 8141 ft/lb

The 223 Short BT is 96% of the 303 Brit.

Web article says typical SAAMI proofing barrels have to withstand  33% -  44% over pressure. http://kwk.us/pressures.html

If so, the Martini can be re-chambered to 223 S using the same action.

This also verifes Tony's Cadet that was modified for 222 Rimmed successfully is safe.

Yes Dorothy, there is a re-chambering Good Fairy!

[rayv]

I was just today thinking about "alternative" hosts .... My thoughts were something like ... hey, bet that .223 Short would be nice in a Thompson/Center rifle.  Hey, bet it'd make a nice T/C pistol, too ... No, wait ... an XP-100!  (yes, my mind really wanders around like that.  Kinda scary.)
I'm interested in the .20 version you mentioned as a possibility, too.  I've been looking around at .20 and .22 wildcats because some are so much more efficient than factory loads.  So many of them are labor-intensive for case forming; makes yours (form, cut off extra length with a Harbor Freight chop saw, trim, load .... no neck turning or reaming) very interesting.  Also, based on the easily available .223 Remington case, rather than something like the way too expensive .221 Fireball.  Looking forward to the next step in the process.  Hope all is going well for the dev team.     

[geezerbiker]

The Aussies rebarrel their .310 Cadet rifles to .222 rimmed.  Since the .22 LR Martinis are made on the same size action but with 50+ years newer steel, I don't see any reason not to use the new .223 short in Martini action.

If you want one to try, you can work on mine... 

Tony