270 Winchester was developed by Winchester when introduced they made rifle and factory ammo available so it never was a wildcat. .277 diameter bullets were created by Winchester for that cartridge here in the states at least and Winchester did not want a metric designation like 6.5 or 7mm so use .277 which might have come from a Chinese bullet that existed but not popular here.

Basically the 270 is simply a 30-03 cartridge necked down for .277 diameter bullet.

I could wildcat a .308 Winchester several times.

6-308 also known as .243 Winchester
6.5-308 also known as .260 Remington
7-308 also know as 7mm-08 Remington
338-308 also known as .338 Federal

^^Brass made for them now. No longer wildcat.

I could also Wildcat 6.5 Creedmoor several times.

6mm Creedmoor
25 Creedmoor
22 Creedmoor

^^Brass made for them now. No longer wildcat.

This is my thoughts as well. Just because brass is made for a round doesn’t mean it’s not a wildcat any longer.
22 Creedmoor and 25 Creedmoor are good examples. Now that SAAMI has approved the 22 Creedmoor and Hornady is now producing ammunition it’s no longer a wildcat.
The 25 Creedmoor unless I am mistaken would still be a wildcat as it’s not been submitted nor is there factory ammo that I have seen.

Yea I would say that’s wrong too. “Improved” performance isn’t always the goal and there are many examples like the 300 Whisper AKA 300 Blackout don’t hold a candle to the 30-30 Win but a wildcat that became popular enough be standardized and my old favorite 6mm/223 aka 6x45 which is still very popular in certain circles and overseas but still hasn’t made it to mainstream standardization.

25 gibbs, 270 gibbs, 6mm international, 257 ai,270 ashurst, 7stw, 30 imperial, 338 06, 30 338, Im sure Ive had other that I cant remember over the years, im kinda tired of fire forming brass nowdays though

When new cartridge case is developed and made available to the public there will be people that like to tinker and have the ways and means to do it will neck it up or down to different diameter bullets and all those will be "wildcats" until they are made as commercial offerings.

Cartridges of the world defines wildcat cartridges as cartridges that there is no factory ammo for or has never been available. That is shortened what a wildcat is defined as per Cartridges of the World which has a chapter dedicated to wildcats.


Edit, to add we got off topic so lets

guilty myself here but did post what wildcats I currently have

Custom barrel makers often play a pivotal role as well by creating something that will chamber modified designs of these existing casings.

6.5-06

One could argue (incorrectly, IMO) that the .256 Newton already claimed that placeholder in the catalog of commercial cartridges...but it's not really just an '06 case necked down to 6.5mm.

25-223 and the 7.62x40
Both are highly accurate and are fun to play with.

I'm not reading all that but anyone with half a brain knows that when a discussion is started about wildcat calibers, an obvious tenet of the topic is that the caliber being discussed is CURRENTLY a wildcat. Almost every cartridge design known to man had to be invented and therefore WAS a wildcat at some point. Bringing up any cartridge from 50+ years ago because it USED TO BE a wildcat is plain dumb.

So good at sticking your foot in your mouth. Custom barrel makers have nothing to do with it. They make calibers .17, .204, .224, .243, .257, .264, .277, .284, .308, .325, .338

Thousands of cartridges fit in that list.

Tool and die makers play a role in new cartridges. Reamers have to be made, to ream out the barrel, brass has to be made or modified, and sizing/seating dies have to be made.

Now is probably the easiest time in history to come up with a Wildcat. I've spoken to reamer makers and die makers. They will do the work, from a drawing. It will take a wait time and money, but can be done.

When I was having fun building AR's, I built a 6x6.8 wildcat. It shot & functioned beautifully. Dies were easy & cheap since I just needed to get a 6mm bushing for my 6.8 SPC die. It was a fun diversion but nothing exciting. I sold the barrel & don't miss it.

My first was the .30 Herrett that kmon mentioned -- for a Contender with 10-inch barrel. I found the case forming much less onerous than expected, using a hardened RCBS trim die with a file. Apply Imperial wax, run her on up, saw off the excess, file her smooth and deburr.
Had the TCUs in 6, 6.5 and 7mm. On the '06 case, 6.5-06, .338-06 and .400 Whelen. On the .30 WCF case family, a .35-30 that I should have kept, and a .25-35 Tomcat project, now in the capable hands of Dave Manson of reamer fame. It was based on blowing out the shoulder of the .25-35 in order to get the 117-grain RN up to about 2800 fps. It was designed around the hearth of Francis Sell's home near the Oregon Coast in company with Sell's friends Parker Ackley and Chick Donnelly, who knew a thing or two about wildcats and barrels. See Rifle issue No. 83 for more on this worthy wildcat.

Remember the 7.62X40 WT

Per the OPs question: I'm down to three wildcats...6x45, 6 TCU and .338-06AI.

Some interesting perspectives here. I'll choose two points to weigh in on:

1) Wildcatting is not now (nor has it EVER been) a driver in the non-standard cartridge development role. A rifled tube (custom or otherwise) neither knows nor cares what cartridge is stuffed in its bum. That's a function of chambering and chambering is the realm of the reamer wizards...always has been, always will be.

2) As much as I love my old .25-06, it ain't no wildcat. If it was old enough to have ".25 Neidner" stamped on it that would be an only slightly different story...but it doesn't. And it will STILL eat factory .25-06 ammo...that's been commercially available since '69!

No wildcats for me. Sounds like something I would enjoy if I had time and space though.

i left out 22 k hornet 22 creed and 6.5 06 and what else

A couple or three