Caliber choices

[johnforrest]

Greetings,

I got interested in 22 TCM and 7.62x25 looking for a better caliber to pair pistols and rifles using the same cartridge.  I already have a 9mm Luger AR and its pretty fun to shoot but is lacking a little horse power for longer ranges. The Tokarev has so much history and fun "other guns" to collect it seemed like the logical choice until the 22 TCM caught my eye. 

I'm starting to realize the TCM pistol side of the equation isn't very reliable and the terminal ballistics are never going to make me feel confident using it on anything bigger than a coyote.  

I wish there was something like a 45 acp case with a .25  bullet that would afford the 'combination" pistol/rifle combo that made the rifle side more effective. 


Is there something I don't know about?


For now the 7.62x25 is gonna be the way I go. Wish it shot a little flatter but that's life, we compromise? 



John

[HMC710]

Hey John,

The possibilities are out there so lets explore a few known and "unknown" with the goal of rifle / pistol round. The first thing we need to do is establish a working length for the pistol, how long is too long?

1.19" = 22 Uzi, 9mm, 357 Sig
1.28" = 22 TCM, 224 BOZ, 9x23, 9x25 Dillon, 38 Super, 10mm, 45 acp, 460 Rowland, 50 GI
1.38" = 22 Reeds Express, 762x25
1.59" = 5.7x28, 256 Win Mag, 30 Carbine, 357 Mag, 10mm Mag, 41 Mag, 45 Colt, 45 Win Mag, 50 AE
1.59+ = 44 Mag

Feel free All to chime in with all the rounds I've forgotten!

Now we need a reliable pistol platform.... and once you get over 1.28", your choices are limited. M57 for the Tokarev, AMT for the 30 Carbine, LAR Grizzly for the 45 Win Mag. The Automag is being resurrected, but its been a long road for them so far. Great read tho, you should look them up.

By far, the 1.28" platform is readily available from Glock and 1911's, so lets stick with that. Unless of course you want to go revolver, and then we can happily run up and over the 1.59"! My woods gun is a Ruger Blackhawk in 30 carbine.

But lets stick with autoloaders and the 1.28" just to run this to the ground. You mentioned you wished the 22 TCM would shoot a bit flatter. Have you reloaded this yet? 3000 fps is reached rather quickly in a carbine, however, it is recommended you make your brass from .221/223 cases if you really want to wake this thing up as TCM brass is very soft. And.... once you start reloading the TCM, you quickly blow past the 1.28" threshold.

To your 2nd question, the .224 BOZ is a necked down 10mm which puts it in the higher pressure range than the 45 ACP.

So its always a compromise, as they say, "Speed costs money, how fast do you want to go?"

[johnforrest]

Thanks Tim



The 7.62x25 is what I wished shot a little flatter. But I still plan to use it for my next AR project. 

After spending some time listening to TCM owners complain about RIA I think I'll wait till they iron out all their issues or there gets to be choices in other brands of guns. 



Thinking about a more ideal round or asking what other possibilities are out there. I assumed using 1.28. So many guns to use it. 

My gripe about the 22 TCM is terminal ballistics. It flys plenty flat for me.  It's fine for a little plinker but something that was a big brother to the 7.62x25 is what I was asking existed.

My unicorn is 30 cal bullet, better trajectory than 7.62x25, still function in a glock or 1911. Then have a AR rifle for it and I would be pretty happy. I think alot of other would be too don't you?

If I'm just dreaming, necking down a 45 acp case and using a 30 cal bullet would be my choice. Easy, cheep components. But I worry about problems underfilling the case? Nothing crazy pressure wise so reloading is easier to stay safe.

Most of the wildcat stuff I see, was all developed for just one type of gun, my thought is to have a cartridge that works relatively ok in a hand gun but able to do real damage out at 200+ with a rifle if you really needed it to. We could also optimize the same cartridge for barrel length and terminal ballistics or make a common load that worked ok in both. 

I just realized I am asking for 30 carbine versatility in a cartridge that would function in a 1.28 mag.

Anyway, I hope you find this as interesting as I do. I appreciate you helping me. Maybe it will turn into something you can use.

John

[HMC710]

North American Arms did a few necked down rounds but they never caught on.

Probably the easiest to do would take the 357 Sig and neck it down to 30 cal and see where you end up. Then to keep it under 1.28, your bullet selection is extremely limited. Some of the .32 cal pistol bullets can be pretty short.

As an aside, but funny story, we were at a bench rest shoot and was testing the 22 uzi between rounds shooting clumps of dirt at the 200m back stop with an 8" ar pistol..... with no sights Got lots of attention!

Yes, very interesting stuff (and expensive and time consuming, both of which I'm limited on...)

Lets see if the Forum will jump in here with ideas on the 30 Unicorn: 1.28" oal, 30 cal, 200 yds.

[johnforrest]

Have you done a 39 super or 9x25 dillon? I didn't realize that the extra barrel length helped their ballistics so much. Reloading something specific for a longer barrel might really be what I am after. Anyway they look like a good compromise so far.

I see you have had a case issue with 357 sig, could that same trouble pop up with these two also?

[johnforrest]

Tim, I am sorry, I just discovered 4 more pages to the firearms section. I thought there was just the one.

[HMC710]

My issues with the 357 Sig were self inflicted..... I assumed because it was a bottle neck that it headspaced on the shoulder. It does not. It headspaces on the case mouth like the 9mm, 10mm, 45acp, etc.

When the last major player stopped making blow back barrels, I stated getting calls. The round, in my opinion, is the worst choice for blow back, High Pressure and Necked Down. 22 TCM is the same way and it has soft brass too boot. Both rounds are asking for case failures in blow back.

When we did our first 357 Sig DI's we also did one based on 10mm brass (9x25 Dillon) I don't know how exact it was, we just used 357 Sig dies and went for it.

The 9x23 and 38 Super both fired out of my 9x23 set up, they are very close in size and Starline makes some "super comp" brass for both for major power.

[squirrelslayer]

There is a guy on Glock Talk who built a 21 and model 40 (with an opened up breech face) to 38 casull (45 acp necked to 9mm) and he's getting very impressive #'s from them.

I too felt a 30 caliber variant would be pretty awesome. Going with a .310 bore could give you the option to run .308-.312 caliber bullets although not ideal it would be a good place to start to see what works best.

This would give you bullet options from those 50gr xtreme cavitator's on up to ~115gr gold dot's (30 carbine or .327 federal) in the pistol (mag length restrictions) then virtually infinite options from a carbine with a mag like Tim is making. Di would allow for higher operating pressures and I would use 45 super brass (stronger web design)

I would like to mention the guy who built the ones on glock talk is running a comp to mechanically keep the gun locked up longer (much like how a 460 rowland operates) to obtain the velocities he's getting. not running a comp would unlock to early and end up catastrophic. So that's something to consider when hot rodding handguns.

Problem going smaller bore diameter than that is bullet selection and mag length restrictions.

I too would like to attempt this concept but from a different approach. I plan to make a modern 7.65 french longue but off .327 federal brass with machined into a rimless case. I would run the full 45k psi and run .312 caliber bullets from a small frame pistol (ie. glock 9mm) this would be very similar to the 7.92 VBR (which was based of shortened 30 carbine brass) I would have to bush a AR bolt to run it in that (or maybe look into a 5.7 CMMG banshee bolt/extension for their radial delayed setup)

Just a word to the wise Wildcatting can be an addictive hobby.

[HMC710]

We use std 556 bolts in our 30 Carbine uppers and have not had an issue.

[squirrelslayer]

The dummy I made has a rim diameter of .337" vs the .360" of a 30 carbine so that's a pretty substantial drop down from .373" of .223

This one was made to a length to fit in a micro pistol like a LCP, P3AT ect... flanked by 32 acp and .380. not sure why I put a 38 spl case in the photo....maybe symbolizing common pocket pistol calibers.

[HMC710]

Good Deal!

[johnforrest]

Well I am hearing about a few 9x25 AR's being built (or they claimed to have been built). But I'm not seeing anything about velocities, reliability, functionality. The $150/ die set is a bit of a buzz kill too. And nobody want to part with their used sets. All in all, it still looks like the best option (performance wise) of anything I'm looking at.

[squirrelslayer]

Wonder if you did something like the 7.5 FK cartridge then if you could find dies just remove .100" from the die and use 10mm brass. 9x25 would obviously be easier but always fun to have something different.


www.fkbrno.com/cartridge-7-5

[HMC710]

I'll see if I have any notes on the 9x25 we did