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View Full Version : Anyone ever make a modern BIG rimfire like 9mm?


repoman1984
08-01-2012, 3:34 AM
Has anyone ever done modern super large "combat viable" rimfire in a modern auto loader? In CA one could have a few more features on their rifle.

Lifeon2whls
08-01-2012, 7:21 AM
Aside from maybe us here in this state and possibly a few others, I don't see the point in developing a cartridge that would really serve no other purpose than to allow additional features on a rifle. I also don't believe that you can reload rimfire rounds so you really narrow the market...hence the rounds become extremely expensive and who wants to shoot that rifle then anyway?

BSlacker
08-01-2012, 10:08 AM
If a 9mm at 450fps is of any use to you go ahead. Rimfire ammo is limited by the material required to make a reliable ignition case rim. In rimfire pressure is low and about half what is found in smokeless powder cartridges of like caliber. The case must be formed over for the primer and then bent by the firing pin so it is weak and won't handle much pressure and still be reliable. :)

Merc1138
08-01-2012, 10:58 AM
Limited market to sell such a product so it would be expensive to produce. There's just no point.

repoman1984
08-06-2012, 2:02 AM
If a 9mm at 450fps is of any use to you go ahead. Rimfire ammo is limited by the material required to make a reliable ignition case rim. In rimfire pressure is low and about half what is found in smokeless powder cartridges of like caliber. The case must be formed over for the primer and then bent by the firing pin so it is weak and won't handle much pressure and still be reliable. :)

true but doesnt a .45 ACP operate on the same chamber pressure as a .22lr?

I was thinking something along the line of a AR-15 style drop in bolt for a cartridge almost identical to a pre-existing center fire cartridge. Offset the firing pin, maybe redesign the extractor and its plausible. One of those things thats only going to be known if its reliable/functionable when its built, thats the problem.

frigginchi
08-06-2012, 4:27 PM
Here you go. Now make a gun for it :)

http://georgia-arms.com/new45autorim230grleadroundnose100pk.aspx

BSlacker
08-06-2012, 4:45 PM
true but doesnt a .45 ACP operate on the same chamber pressure as a .22lr?

I was thinking something along the line of a AR-15 style drop in bolt for a cartridge almost identical to a pre-existing center fire cartridge. Offset the firing pin, maybe redesign the extractor and its plausible. One of those things thats only going to be known if its reliable/functionable when its built, thats the problem.

Yes, but the 22lr is pushing a 40gr bullet and the 45ACP pushes a 230 grain bullet. The force/push against breech face is larger with the increase in bullet weight. :)

Here you go. Now make a gun for it :)

http://georgia-arms.com/new45autorim...nose100pk.aspx (http://georgia-arms.com/new45autorim230grleadroundnose100pk.aspx)

This is a centerfire cartridge it is for shooting 45 ACP from a revolver. :)

frigginchi
08-06-2012, 5:15 PM
Says rimfire :confused::confused:

http://www.ammonow.com/handgun_.45_Rimfire_page_1.html

Yes, but the 22lr is pushing a 40gr bullet and the 45ACP pushes a 230 grain bullet. The force/push against breech face is larger with the increase in bullet weight. :)



This is a centerfire cartridge it is for shooting 45 ACP from a revolver. :)

BSlacker
08-06-2012, 5:28 PM
Says rimfire http://www.calguns.net/calgunforum/images/smilies/confused.gifhttp://www.calguns.net/calgunforum/images/smilies/confused.gif

http://www.ammonow.com/handgun_.45_Rimfire_page_1.html
It is on a page labeled rimfire. The .45 Auto Rim itself is a centerfire cartridge intended to fire in .45ACP revolver without moon clips.
It is just on a page labeled rimfire it is not rimfire.
If you look a little further down the page you offered you will see a picture and they are centerfire. There are plenty of .41 cal rimfire ammo but it is under powered. :)

http://en.wikipedia.org/wiki/.45_Auto_Rim

The peak pressure is the same but the reaction and timing are not. At ignition the 22lr has a small volume of propellent it burns quickly and moves a light bullet, (40gr) the opposing force. So with the rimfire we have a shorter impulse and a equal and opposite reaction from a 40gr weight and the space volume is increasing after the propellent is burnt quickly. With a .45ACP there is a larger volume of propellent to burn longer and provide a longer impulse as well as a heaver weight to move (230gr) so more opposing force to move the case. If it would work it would work.