How to neck down straight walled cases

[rplaw]

I want to build something (someday) and it'll probably be chambered in .22TCM. I know the ammo/brass for the .22TCM is available for reloading, but researching the round got me wondering.

How would someone go about necking down a cut-down case?

For example, the .45ACP rim diameter is .480 and the base is .476. If I were to cut down a 5x57 Mauser case (rim diameter .473, case diameter of .472) to produce a case length of .898, how would I neck it down to accept a .22 bullet?



Reason for asking:

This case would have slightly more volume than the .22TCM (thereby reducing the powder compression issue with 45gr. bullets) and would fit the 1911 magazines better than the .22TCM does - they supposedly rattle a bit in the 9mm mags.

Also wondering why this wasn't done originally instead of using the smaller .223 case...

[Dirtlaw]

Keep us posted. That's an interesting round. I thought the weapons were not on the CA list though. Is that not so?

[DrewN]

It's a drop in conversion is my understanding (if you use RIA parts), like their 9mm/.38 Super. The only RIA Super we can get is a GI model, but the 9MM was available with ambi safeties etc. Evidently it's just a linked barrel swap. Their website also shows Glock 17/19 and 1911A1 complete top ends.

[pacrat]

How would someone go about necking down a cut-down case?

SHORT ANSWER ................ Incrementally. By utilizing ever smaller dia sizing operations. In steps. Until desired case diameter and overall profile is attained.

Often requires annealing between operations.


Have fun

[rplaw]

Keep us posted. That's an interesting round. I thought the weapons were not on the CA list though. Is that not so?

I want to build a ghost gun with this chambering just for the "hey wow" factor.

7" slabside longslide, alum frame with super extended dustcover, titanium nitride barrel, slide cutouts, custom engraving, yada yada yada... Definitely a BBQ gun.

In .22TCM it would have almost zero recoil. And, it might even make major power factor with the right bullet.


What I want to know is how to neck down a case after I shorten it. In case I want to make my own cases at some point. Or go up in case volume and ream the TCM chamber for the larger case.

Is this a multi-stage process?

[rplaw]

SHORT ANSWER ................ Incrementally. By utilizing ever smaller dia sizing operations. In steps. Until desired case diameter and overall profile is attained.

Often requires annealing between operations.


Have fun

Hah, you posted while I was typing.


So, different stage dies? Or 1 die getting slowly "tightened" with each setup?


I'm really just asking because I'm bored today. Someone has probably already done this with the .45ACP case (.22BOZ?) already.

[Toxic Shock]

Cutting a rifle cartridge to .898" length and then necking down is a non-starter. The case walls on a standard rifle cartridge will be way to thick for doing this. Even with neck turning or reaming the shoulder area will be way too thick. It's better to use the proper brass for something like this.

[pacrat]

So, different stage dies? Or 1 die getting slowly "tightened" with each setup?

Going 45 to 22 reduction would likely take 3 steps of reduction to complete without crushing the case in the process.

That's 3 different sizing ops, using 3 different dies. I know of NO sizing die that is adjustable for diameter.

Your prospective "volume" results have a likely flawed expectation.

For example, the .45ACP rim diameter is .480 and the base is .476. If I were to cut down a 5x57 Mauser case (rim diameter .473, case diameter of .472) to produce a case length of .898, how would I neck it down to accept a .22 bullet?

The internal WEB of a rifle cartridge designed to support 60,000 + PSI. Is much more substantial.

Than the WEB of a comparable dia pistol cartridge. designed for sub 20,000 PSI containment.

Adding the wall thickness difference that "Toxic Shock" already mentioned. You would likely go to all the fuss to make a case with LESS volume.

Going the .898" case length. Why not start with the 45 acp case?

It starts out a bit larger dia than the 7x57 and doesn't have the Wall/WEB volume issue.

[DrewN]

Isn't the 22TCM parent case a 5.56?

[pacrat]

Isn't the 22TCM parent case a 5.56?

Yes

https://www.google.com/search?q=22+tcm+cartridge&oq=22+tcm+cartridge&aqs=chrome..69i57j0i22i30l9.7123j0j7&sourceid=chrome&ie=UTF-8

The .22 TCM or 22TCM (.22 Tuason Craig Micromagnum) is a proprietary bottle-necked cartridge created from a 5.56 NATO cartridge developed by custom gunsmith Fred Craig and Rock Island Armory (RIA) for semi-automatic pistols and the Rock Island M22 TCM bolt action rifle.

[rplaw]

Going 45 to 22 reduction would likely take 3 steps of reduction to complete without crushing the case in the process.

That's 3 different sizing ops, using 3 different dies. I know of NO sizing die that is adjustable for diameter.

Your prospective "volume" results have a likely flawed expectation.



The internal WEB of a rifle cartridge designed to support 60,000 + PSI. Is much more substantial.

Than the WEB of a comparable dia pistol cartridge. designed for sub 20,000 PSI containment.

Adding the wall thickness difference that "Toxic Shock" already mentioned. You would likely go to all the fuss to make a case with LESS volume.

Going the .898" case length. Why not start with the 45 acp case?

It starts out a bit larger dia than the 7x57 and doesn't have the Wall/WEB volume issue.

The case has to be stronger than the 9mm/.38 super/.45ACP case because of the higher pressures. I think .357 mag is only something like 38,500(?) and the .22TCM is around 40,000. That's why the TCM uses a rifle cartridge case to begin with.

The case length/COAL is limited by the magazine size. .45 case length is .898. Anything longer isn't going to fit in the magazine unless you want the bullet buried in the case. Which will add pressure to an already very high pressure cartridge.

As for volume, someone would have to measure them to be positive but I think that the 5x57 should have a skosh more interior room. Not a lot, but even a few grains of "breathing room" would help prevent powder compression but I don't really know if this is actually a problem or not. It seems like everyone is concerned about it, but they load like that anyway.

As a final point; for me, at this time, this is merely a mental exercise just for the information and knowledge. The gun this would be chambered in is years down the road (if ever) and I have 2 projects in line ahead of it, plus getting my floozy gun back together (waiting on a new plunger tube).

[LynnJr]

Buy a skip otto die from Butch Lambert at shadetree and your all set.

[Fat Albert]

Extractor cutout.

No one has has talked about the extractor cutout. The cutout on the 45ACP and the cutout on a standard Mau. case(308-243-270-30/06) are not the same. Different angel/dia./heights. I collect cartridges and the first 45APC (pre WW1) had /06 extractor but that was changed. Just put the two cases next to each other and it stands out like sore thumb.

[Dirtlaw]

So are 22 TCM guns now available in CA????? I was interested a long time ago, but the weapon was not available. This post has revived that interest.

[ar15barrels]

Also wondering why this wasn't done originally instead of using the smaller .223 case...

Because such a fat case will be difficult to feed and not fit into as many different handgun frames.