can anyone educate me on the .38 JT rimless

[jonsidneyb]

Hello,

I was wondering if someone can tell me what is different about the .38 JT rimless .38 Super from other rimless .38 Super casings.

Is this cartrige capable of 9x23 loads safetly?

I cannot find much on the net about this cartridge.

[ClarkEMyers]

The .38TJ has a distinctly different extractor groove profile (sort of like the difference between the .308 and the .30-'06) which throws the inside base of the case farther into the chamber. Some say this means the extractor is likely to benefit from tuning specific for the .38TJ.

I don't know that the 9X23 is capable of 9x23 loads safely and I shoot one in a ramped barrel. There are significant differences in water capacity of the empty case - generally the .38ACP or .38Super even rimless oddballs run more capacity than the 9X23 empty. Loaded capacity of course depends on seating depth and to some small degree on bullet base - a beveled base giving an infinitesimal greater space for the same depth. I tend to think that I'm loading the 9X23 to higher pressures but with a smaller case capacity so higher pressure for same weights of powder so I don't consider the data interchangeable. I do think that either case could be loaded to equivalent bullet velocity or power factor. BUT not with identical loads. In particular starting with full bore .38 Super-face loads in a 9X23 is a recipe for disaster.

Notice that the .38TJ is not a cartridge but a cartridge case and like the 9X23 you won't find a lot of SAAMI spec information. I'd suggest forums like Brian Enos or the various 1911 specific discussion groups. One of the popular groups, maybe even this one?, recently had a picture posted showing each of the various .38ACP cases sectioned and laid side by side - if and when I run across it again I'll come back and post the link.

[ClarkEMyers]

See Brian Enos forum for a lovely picture of most of the .38ACP/+P/Super lot, sectioned and laid out side by side including Lapua and Starline Supercomp as well as the Hornady Todd Jarrett for rimless. I'm not sure that I'd push limits in your Tanfoglio hicaps.

I rather suppose the .38TJ will kill demand for the 9X23 in race guns and that might reduce demand in carry guns and so lead to the decline of factory loads and Winchester brass. On the other hand the loads from Corbon and such are encouraging for the 9X23 and some of the necked down speedsters may decide the issue in the end. It may boil down to how much support Hornady maintains for the .38TJ - I hear the family will indulge themselves to a point but I don't expect the .376 Steyr to endure much longer and there are others.

[jonsidneyb]

I currently use 9x23.

I was thinking of changing to a rimless .38 super casing but am a little bit wary of it.

I would like to get a real 1450 fps with 124 bullet so I am not asking for the world if you are used to 9x23.

I have a couple of reasons for wanting to do this.

[eerw]

The 38 TJ offers a deeper larger extractor groove than the the other 38 super rimless type cases..the 38MCM was just a rimless 38 super as is the 38 supercomp..so the extractor groove is shallow..hence the popularity of the Aftec extractor...more consistent pressure from the springs..for extraction..

there was some article..where the writer got Hornady to run a loading of 124grJHP in TJ brass at about the velocity you are wanting...

the brass should hold..as 124gr bullet at 1450 is about what IPSC shooters would run when the old PF was 175. but note that is through supported 1911 style barrels.

so in a 1911 with the right powder and a supported chamber..the velocity you are seeking with that bullet weight should be attainable..as long as you are careful with your loading..and watch for pressures..

I would suggest using a hard primer to minimize the primer flow also..

what advantage do you see switching from WIN 9x23 brass to a rimless 38 super case??? the TJ brass is pretty expensive and about as available as WIN 9x23.

When I shot WIN 9x23 I was easily getting 8-9 loadings using a 115CMJ and 124CMJ bullet shooting at about a 171 PF with WIN SR primers.

[ClarkEMyers]

The .38TJ is about as good as it gets for making major in high capacity double stack magazines - though I do prefer the 9X23 in single stacks. It's perfectly straightforward to make your desired velocity with the lighter 115 grain bullets.

I am informed that the 9X23 case is definitely a stronger case than the .38TJ. I have made no particular tests of my own for the limits of the .38TJ - rather I have and will continue to use the 9X23 case for loads beyond SAAMI - again I have not and won't test the limits of the .38TJ myself. I do agree that the .38TJ is more likely to meet your desire for feeding in large double stack magazines - assuming good lips and release point and all the rest.

I do have adequate stocks of SP2 (and WAP) among other powders and SP2 does a fine job for high velocity with heavier bullets in the 9X23. On the other hand there can be wide spreads - large standard deviations - however one might choose to express inconsistent performance - I'd have to shoot a lot of hot loads in the .38TJ to trust the velocities will be consistent. I'm not going to bother myself.

However though 1450 with 115 grain bullets in the .38TJ is well plowed territory to the best of my knowledge and belief 1450 with 124/125 grain bullets in the .38TJ is experimental territory. I am by no means saying it can't be done. I am saying that for my understanding you will be on your own. I don't expect to see many published loads with attribution that exceed SAAMI specs by much. With a 124 grain Hornady FP Todd Jarrett himself reports 1497 fps for a 185.6 power factor with a considerable amount of WW540. There may be folks on the Brian Enos forum with more to say on the subject.