rechambering .22 rimfire to centerfire

02 September 2003, 06:11

I forgot to post the second question I had about my plans to rechamber a Martini International to .22 Hornet.

I understand .22 rimfire barrels have a diameter of .223, while .22 centerfire's use a .224 diameter tube. If I want to convert to Hornet, do I need to rebarrel, or can I use the rimfire barrel? I assume I can push a .224 bullet down the 1/1000" smaller bore, but I am concerned about the impact on pressure.

02 September 2003, 06:51

Vibe

I can add a small bit to this. I've done it. Not with a Hornet though. I necked the 25ACP to 22 and use Hornady bullets in them. I've done 3 or 4 rimfire barrels this way. I DID have pressure problems when I tryed to use the Rem 45gr HPs, but so long as I used Hornady bullets I've had no pressure problems. There may be other manufacturers that will work as well, and in fact Rem may work for you. Just back off to about 1/2 loads to start with a new bullet when working up loads. Some will work, some may not. Of course my BEST loads to date only push the 35gr V-Max to 1850fps and the 45gr V-max to around 1600fps. I know you are looking for more than that probably. But since I had done it before thought I would chime in. In truth the rimfire barrels are closer to .222 unless it was a 22 Magnum, then it's the same as the centerfires.

02 September 2003, 13:11

rupert

There is no problem re barrel dimensions. Conversion of the Cadet action was common in Australia (to 222 rimmed and others) when the action/rifle was cheap. I have a 12/15 converted to centrefire and 22 Hornet and it produces quite satisfactory groups without pressure problems using 40gn HP Sierra bullets and Lil Gun. So that 22rf barrel will work quite well and the steel is normal nickel steel, not some sort of inferior stuff.

02 September 2003, 13:36

Hot Core

quote:
Originally posted by markb:
...I understand .22 rimfire barrels have a diameter of .223, while .22 centerfire's use a .224 diameter tube. If I want to convert to Hornet, do I need to rebarrel, or can I use the rimfire barrel? I assume I can push a .224 bullet down the 1/1000" smaller bore, but I am concerned about the impact on pressure.

Hey Mark, Some 22 rimfire barrels are even smaller, in the 0.221"-0.222" sizes. Don't remember where I got that tidbit, but the only way to know for sure what your barrel is, is to "Slug" it.

As far as 0.223" Jacketed bullets, they are still being made as well as the much more common 0.224". Back many years ago the original 22 Hornets all used 0.223" bullets. I know Sierra still makes them, but haven't looked at the others lately. Maybe some of the other Bullet Manufacturers do too.

I'd suggest as far as the bullets Spiking the Pressure in your barrel, each barrel needs to be judged on it's own merit. It isn't a good idea to "assume" that just because someone else has been able to do this without Pressure Problems, that you will not experience them either. Though I can see where the information is nice to have.

So, be particularly aware of the Pressure Ring Expansion on your cases as you fire them.If you go ahead with this project, ask for a SAAMI Minimum chamber and I'd even suggest that getting the K-Hornet chamber might help you as much as anything.

Going through a project like this only to find out you have now got the typical Hornet Problems of short case life and sporadic accuracy would certainly not be fun.

Best of luck to you on the project.

02 September 2003, 16:00

Clark

I was thinking of converting a 22 LR to .223 for fun, but a someone pointed out to me, the steel used in 22 LR barrels is soft and will not stand up to high velocity.

03 September 2003, 02:16

J Wisner

First slug your barrel and find out what diameter the bore is.

About 30 years ago I took a #12 action and fitted a Remington 513 barrel to it. Chambered it for a 218 Bee, Shot I don't know how many crows etc with it. However the Remington barrel has a .2225 bore in it. So always used Speer or Sierra 40 or 45 gr. .223 bullets in it.

Jim Wisner