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
Reply to
etpm
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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.
Reply to
John B.
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Reply to
Jim Wilkins
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.
Reply to
Ed Huntress
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
Reply to
etpm
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
Reply to
etpm
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.
Reply to
Ed Huntress
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
Reply to
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.
Reply to
Ed Huntress
A couple of years ago I sold my .240 Gibbs. It used a fire-formed 30-06 case necked down to .240. What a rifle! I sold it because I couldn't afford the optics it deserved and had no place to stretch it's legs, no 1,000 yd ranges near by and the closest one didn't have golf carts.
Back to the subject, I think there is no advantage to wildcatting anymore, there are rounds for everything that have been perfected and components available. I'm shopping for a 6.5mm Grendel or such that will fit on the closest ranges. There are a lot of @6mm rounds for an AR-15 platform that are extremely fine tuned.
Reply to
Tom Gardner
Yeah, I agree. The wildcatters from the '30s through the '60s had a point, but there must be five cartridges for any reasonable purpose today.
It sure was fun, though. When I was in my early teens, my best friend's very wealthy dad had around 20 custom wildcat rifles that we used to shoot every other week or so, all four seasons of the year, at woodchucks and crows. I shot a few that were wildcats then but which are now commercial cartridges, from the .220 Swift to the .25-'06, and a few that never made it -- the .22-3000 Lovell, the Ackley Bee (I think they retained the .218 designation for the cartridge from which it was derived, but I forget), and a .219 Zipper built back in the '30s, before anyone had made a bolt-action rifle for it, on an old Win. receiver (Model 54 or Model 70 -- again, my memory isn't that good). It could still drive tacks and slaughter crows.
I gave it all up when I was around 15 and decided to stop shooting anything I couldn't eat. Woodchucks were OK, but I wasn't going to try a crow. Then I bought my Browning 1885 in .223 for hunting javelina (killed one with it near Apache Junction, AZ), and almost got back into varmint hunting with it, but you need to own a farm in NJ, or be invited to shoot by an owner, in order to shoot varmints with a centerfire rifle. My farm-owning friend sold his farm.
So I sold my Browning in disgust. I did make close to $400 profit on it, though.
BTW, if anyone needs woodchuck recipes, I have a few from the old _Gourmet_ magazine. No kidding.
Reply to
Ed Huntress
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
Reply to
Martin Eastburn
It was shooting a .220 Swift that got me interested in rifles. Everybody should shoot one at least once in their lives.
Reply to
Tom Gardner
It's capable of even better with no wind and the planets aligned. There is a 500 yd range not too far away and has golf carts. I'm looking at the 6mm AR Turbo also. I sold two Mini-14's and have a SKS for sale to finance such.
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Reply to
Tom Gardner
Out of curiosity , what's an SKS worth these days ? Say a Russian pre-ban with full kit , including bayonet and cleaning kit and oil/solvent container .
Reply to
Terry Coombs
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
Reply to
etpm
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.
Reply to
Ed Huntress
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.
Reply to
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.
Reply to
Ed Huntress
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Hmm ... ever seen the .22 Remington Jet? A .357 Magnum necked down to .22. Long taper and a problem backing out in a revolver -- it tends to bind the cylinder from free rotation unless you really clean all oil out of the cylinder bores and off the case.
Enjoy, DoN.
Reply to
DoN. Nichols

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