I'll start with I had an extra 6" g20 9mm sitting around with no purpose as well as a bunch of SPP 45 acp brass.  I got to thinking...  I remembered the articles back in the late 90s about the 38 casull and the speeds they were getting which were impressive at the time (124gr at 1800 with h110).  I figured I could possibly make this a reality so I contacted my friend who does some smith work and he believed it could be done.  The goal was to recut the 9mm chamber to a 38/45 add a comp and run it in my g21 longlslide.  This will be loaded to 38 casull specs, not the old 38/45 specs.     

I looked on ebay and found a like new 38/45acp die set for sale that I won for about half price over a new set from rcbs.  Then after I received the dies I "tried" forming acp brass in a single stage but that was a bit far fetched.  The forming die from rcbs was also a pricey piece but looking at pics the form die resulted in something very close to the 400 corbon.  So i grabbed a lee 400 corbon dies set for $30 and bingo I have the right combo for good looking brass!

I made a few dummies up with the heaviest bullet I planned on using and sent the barrel and slide assembly off to get chambered.  Comparing the case capacity to the 9x25 Dillon the 38/45 case held about 1.5g more of 300mp when filled to the top.  Should make for some good numbers and that big sharp shoulder should help with getting the slow powders burning (Its like a WSM pistol round).  The barrel has been chambered and has great case support right up to the extractor groove.

So far the preliminary tests have resulted in a 125gr xtp (.357 dia) over 20.5gr of h110 averaged 1876fps and 977lbs of energy.  WIN standard LP brass and WIN LP primers were used for this load.  The standard LP primers were starting to flatten at this level but case heads were still down at .479".  This gun will be running a compensator on it shortly and should be very effective at taming the beast since.

My ultimate thought with this project was to have something "unique" that had cheap plentiful brass with 357mag ballistics but was soft shooting.  The goal wasn't really to be a light bullet at rifle velocity setup but it looks like it may be great as a coyote pistol!  I'll work up to 180gr pills over slow powders and see what it can do.

Not too bad for an old wildcat!

Yes I call it the 38wby as it reminds me of the weatherby rounds.
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I had drawn up some plans for a 9/45 (45ACP necked down to 9mm). Basically, the same thing. I didn't have access to a machine shop, so it never got past the drawing stage. 

I built a 38/45acp back in the 80's using a 38 Super barrel. I used a Gov't model 1911 Colt. Did all of the Gold Cup mods to it. It shot pretty good with groups at 25yds from bags at an inch with 125gr HPs. All it turned out to be was a 357 semi auto. I had tons of issues with cases that would split during the forming process. And that was using annealed brass. Brass life in mine was a paltry 3 times thru the gun and it was done. Split necks were common. I still have it but it's probably been 20 years since I've seen it. I guess I should dig it out of the vault one of these days. Then there's finding the ammo and all things considered, that's probably why I won't be shooting it any time soon. Far too many that I load for and far too much of too little sitting in the cabinets and boxes.

I'll consider my self fortunate then!  I just made up about 500 pieces of brass and only messed up 2 so a .4% failure rate is pretty good in my mind.

I'll start working up more data in the next few weeks but I believe 2000fps with a 125gr is attainable with what I've seen so far in my gun.  I'm more interested in the heavier bullets but it's always fun seeing the chrono edge closer to that 2000fps number.

The original .38/.45 Clerk (pronounced Clark) was a fairly good performer. a modern, "Magnum" level version should prove interesting.

Ok some time has gone by since I updated this so here we go...

We decided to make a bit of an improved round so we shifted the shoulder forward .030".  We wanted more capacity plus no next tension issues so 30 thou worked nicely (see pic of the normal and improved case).  Capacity of the improved puts it about 1.5g ahead of the 9x25 dillon when filling all 3 with 300mp powder.

So far I have only tested 300mp in the gun which is very slow, but was a safe one to work with. 


So far I my best results have been:
125gr, 22.0g 300mp 1877fps avg,  977lbs of energy.
158gr, 17.5g 300mp 1511fps avg, 800lbs of energy.
180gr, 16.0g 300mp 1448fps avg, 837lbs of energy.

All loads were with blazer SPP 45 brass and S&B small rifle primers

Case heads were no larger than .4755".  I'm running out of room in the case and may be able to a little  higher in these loads with 300mp.  H110 is a touch quicker burning and my yield better numbers still?  I'll max out the 300mp before swapping powders but overall I'm happy with the results so far!

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Interesting cartridge and setup! 

Maxed out the 300mp over the weekend with the 125s and 158s.  I didn't bother with 180s because I was already close to full compression with 16g.  The 16g load was also very accurate so I'm happy with that. 

Blazer SP brass and S&B SR primers

125gr xtp over 22.5g 300mp avg 1969fps/1075ft-lbs
158gr php over 18.5g 300mp avg 1604fps/902ft-lbs

Case heads ran .476" (very low still)

Overall I was very impressed with 300mp with the velocity and vs case head.  I will begin h110 and aa9 workups soon.

Nice work ss. Please keep us updated.

Thanks,
Keith

Is this a modern version of the .38/45 Clerke?

Yes sir it's essentially a 38/45 clerke improved loaded to 460 Rowland pressures.

This may be fine if one uses .45 Super brass. As long as the pistol is properly set up for it (flat-bottomed firing pin retainer, progressive springs to 26 lbs at the apex of compression, etc.). I like the idea, but the 9 X 23 Winchester seems to have been done first.

I'm not trying to be offensive and correct me if I'm wrong, but isn't this "reinventing the wheel"?

Not really reinventing per say but enjoying  something different.  Really my goal was to have a purpose for spp 45 brass so making a bottleneck round and using SR primers worked well.  My method for slowing down my slide speed is the 2 port comp pictured on my gun.  Since its not a 1911 there is no flat bottom fps option to use.  My barrel has case support up to the extractor groove so I don't have a need to use 45 super brass.  I believe that SPP cases are stronger than LPP cases anyways so it's worked well for me.

Compared to the 9x23 or 9x25 Dillon the 38/45 is a different animal all together.  The 45 case has less mag capacity obviously but will surpass the others ballistically. 
With 125s the 9x23 will get you 1500-1600fps the Dillon will get you around 1800fps and the 38/45imp will get you near 2000fps.  Whether it's worth it or not is up to the individual.

I swapped my s&b primers with cci400s and re-ran my 22.5g 300mp load with the 125 xtp.

5 shot average has just been bumped to 2014fps and 1125lbs of energy!