Rimless cartridge question

I know, it's a nutty idea but I designed a centerfire .22 round. Dunno yet whether I'll ever make any because it also means modifying a bolt
or making a new one for one of my .22 rifles.Today while eating lunch and looking at a rimlesss cartridge I thought about making a rimless .22 centerfire cartridge simply because it would mean less machining. Looking online I see that rimless cartridges locate against the shoulder. So when rimless cartridges are fired they can't grow in length like rimmed ones can, right? If I make a rimless .22 cartridge it will be .250 diameter. The bullets will still be the same dia. as normal .22s of course. But maybe I can get away with a bullet with a constant diameter instead of the traditional .22 rimfire design. That would make it easier to make the bullet molds. If I did that would the bullet still need to be crimped in the shell the way a .22 rimfire would be? My rimless design would increase the shell dia. to .250 so that way the O.D. would just be the dia. of the stock. If screw machine stock is used the the O.D. of the shell case will be very consistent. Maybe I can get away with just pressing the bullets in. Eric
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On Tue, 05 Apr 2016 17:50:53 -0700, snipped-for-privacy@whidbey.com wrote:

How are you going to extract this thing? Or will it have a "head" with a recessed extraction groove, such as larger centerfire cartridges? If so is it going to cost more to manufacture then the .22 rimfire cartridges. Is there an advantage ?
If you are going to use cast lead bullets, aren't lead bullets normally lubricated? And is so how will you lube your constant diameter bullets?
Cases are usually crimped to hold the bullet tightly. If you don't crimp the bullet then the cartridges will have to be handled a bit more carefully and probably should only be used in a single shot weapon. I've seen 44 Magnums jar bullets that aren't heavily crimped, far enough out of the case that the cylinder wouldn't turn.
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John B.
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wrote:

The rounds would resemble any other rimless cartridge, just smaller. I am not looking at having someone else make these, I am gonna make 'em. And a rimless case will require less time and smaller diameter stock. I know standard rimfire .22s have crimped cases and need to in order for the correct pressure build up. I have seen rimless rounds where the bullet is just pressed in and I was wondering if I could get away with that, especially since I want low velocity. I shoot CB shorts because they are so quiet but they are expensive and hard to get, they always seem to be out of stock unless I want to pay fifty cents a round. Eric
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Just use .251 bullets. Have a gun to shoot it ? Thompson pistols have pins that shoot center or rim.
I'd look at the .25 auto cart. and think of that.
Martin
On 4/6/2016 11:03 AM, snipped-for-privacy@whidbey.com wrote:

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I'm not sure either. At this point I am just thinking about what would be required for a rimless cartridge and if it would be worth the effort. Timewise it would seem to be a waste but I like making things, especially out of metal, and I like shooting. Having a machine shop and being a machinist makes it easier to make things. All the comments posted so far relating to my first post have been a good education. Eric
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On Mon, 11 Apr 2016 09:11:57 -0700, snipped-for-privacy@whidbey.com wrote:

I mentioned earlier that .22 rimfires have ground glass in the primer and that they rely on the crimp to build up pressure. Or they did, 30 or 40 years ago, when I learned those things.
Wondering if they still use the glass, and what the current thinking is on crimping rimfire cartridges, I came across this informative piece from _American Rifleman_:
http://www.americanrifleman.org/articles/2010/9/10/the-impossible-22-rimfire/
Maybe this will add to your store of knowledge. The story on crimping centerfires is full of arguments and opinions, but this is the clearest piece I've seen on rimfires.
--
Ed Huntress

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wrote:

The .22 developed around 1845 from a lead ball in a percussion cap for indoor practice. The rim was soon added to eliminate slow and clumsy ramrod extraction. Being the first metallic cartridge, preceded by only the pinfire paper shotshell and a few dead-end caseless experiments, and meant as a toy it didn't have the strength or consume as much metal as 1860's military experience proved necessary.
It's NOT a good example to copy in any way. Cased ammunition wasn't substantially perfected until around 1870, and settled into the 'modern' form between 1890 and 1900.
http://www.chuckhawks.com/history_rimfire_ammo.htm
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On Mon, 11 Apr 2016 12:24:40 -0400, Ed Huntress

Thanks for the link Ed, I'll read it this evening. Eric
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You are missing the point. It isn't the cartridge in the chamber that is the problem it is the cartridges in the magazine/cylinder that cause the problem. As I believe I've said, I've seen 44 Magnum revolvers lock up because the bullets move far enough that the bullets protrude from the cylinder.
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John B.
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http://castboolits.gunloads.com/showthread.php?37184-Velo-Dog-revolver-reloading
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On Tue, 05 Apr 2016 17:50:53 -0700, snipped-for-privacy@whidbey.com wrote:

Machined brass needs thicker walls, remember, because it isn't work-hardened. There are some wildcatters who harden their machined brass by fire-forming it, but that's for the experts.

The necks can grow from the shoulder forward. Depending on how it's loaded, the cartridges may have to be neck-trimmed after a few firings.

That depends on what kind of gun you're going to shoot them in. I handloaded for my Browning 1885 without crimping, but that's a single-shot rifle. No problem.
You're biting off a big bite. I also designed a cartridge and got pretty far along with it. It was a .32 S&W Long necked down to .22 caliber. I made my own cherry and started to ream a chamber before I was cautioned by a wildcatter I met in the ASSRA. He told me the walls were 'way too thin on that cartridge for what I wanted to do.
So my replica Farquharson falling-block action still sits there, waiting for me to retire and do something about it.
--
Ed Huntress

>Eric
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On Tue, 05 Apr 2016 23:09:47 -0400, Ed Huntress

Greetings Ed, I want to be able to shoot a CB short type round. Low energy. The rimless round I drew up has thicker walls than a standard .22 case. If I use a standard .22 bullet with the smaller diameter heel the wall thickness is .022". If I use bullets that are a constant diameter then the wall thickness where the bullet is would be .014". A standard .22 case has .010" wall thickness. Even if the machined case is weaker won't the chamber support it? Eric
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On Wed, 06 Apr 2016 09:11:12 -0700, snipped-for-privacy@whidbey.com wrote:

In terms of specific measurements, you're over my head. .22 rimfires are very specialized beasts today -- special powder, ground glass in the primer, etc. Their pressures run around 20,000 CUP, I'm told, and the difficult priming, combined with the thin case walls, makes it necessary to crimp them hard to get reasonably consistent ignition.
When you go to a very small centerfire, like you're describing, ignition is likely to be much better because of the central port, but everything else changes, as well. As you know, centerfire cartridges typically run higher pressures -- up to 50,000 CUP in some handloads. Benchresters and single-shot folks often (generally?) don't crimp. They just get a mild interference fit, and swage and ream cartridge mouths for consistency.
Centerfire case-wall thickness comes into play with hot handloads, which is probably what most of the machined cases are used for. I have no idea what kind of pressures you're going to develop with those tiny cartridges, but I'm naturally cautious, and I should point out that the worst case of head separation I ever saw, back when I was a varmint-rifle fanatic, was on little handloaded .22 K-Hornets. There are a lot of mysteries that go into pressures, including shoulder angle, powder type, powder space, etc.
I don't have the knowledge to evaluate those things, but, when you were talking about machining your own brass, I thought I should point out that you don't want to make it as thin as rimfire brass, and that your brass won't even be as strong as regular drawn (actually, back-extruded) cartridge cases.
I watched a .25/06 blow off a cartridge head once, back in 1961, when they were still wildcats, and this one was loaded very hot, shot in a sporterized /03 Springfield without the Arisaka safety conversion. That scared me for life. Fortunately, it did not *scar* anyone for life. But it came close.
--
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I certainly understand wanting to do it just prove you can...
I don't see why hand loading a subsonic round in a small pistol standard cartridge won't do what you need. No reason not to cast your own boolits. I'd suggest the TOK round. other possibilities.
Karl
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On Wed, 06 Apr 2016 14:22:57 -0500, Karl Townsend

With a 50-gr. bullet, a commercial .25 ACP runs around 780 fps out of the muzzle. It's a semi-rimmed and you could download it to watch the bullets fly, if you want. <g>
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On Wed, 06 Apr 2016 14:22:57 -0500, Karl Townsend

I won't be shooting a pistol Karl. I am considering converting a bolt action Remington I already have. I'll have to google the TOK round. Eric
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On Thu, 07 Apr 2016 08:36:51 -0700, snipped-for-privacy@whidbey.com wrote:

There's no reason you can't use a small pistol cartridge in a rifle. In fact, that's where I got the idea for my own wildcat. I saw a rifle built for single-shot (offhand -- scheutzen) indoor competition using .38 Spl. cartridges.
The .25 ACP sounds like it should be about what you need. It has a small rim and an extractor groove ("semi-rimmed"), so you can seat it on the rim.
--
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I would have suggested .25 ACP as well, but thought he said "headspace off the front of the cartridge" in the specs. TOK is the smallest bottle shaped cartridge i could think of.
And yep, lots of rifles use pistol rounds. I have a huge collection of 9mm rifles. mostly sub machine guns from the WWII era rebuilt into semi auto.
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On Thu, 07 Apr 2016 11:56:44 -0500, Karl Townsend

I got a little lost in that part of the conversation, but I thought he was interested in that because he had thought of making 0.250-dia. cartridges out of 0.250 stock, and would have no rim to work with.
With the .25 ACP, he'd have a modest-sized rim -- enough, I think.

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On Thu, 07 Apr 2016 12:04:11 -0400, Ed Huntress

If I remember the .25 ACP has a primer. It might be mentioned that the quick draw crowd that uses/used wax bullets used a rifle primer and no powder to fire wax bullets. If he is trying to match the ballistics of a .22 CB it might be a solution.
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