Modified 357 maximum

[Gohon]

I have a NEF 357 magnum I've been playing around with.  Having received a new RD TLC-359-190-RF mould I wanted to see what they would do in the 357 mag Handi.  Loading the 190 grain bullets ahead of 13.5 grains of Lil'Gun it was a easy 1" groups at 50 yards.  Through my Chrony they clocked a average of 1676 fps.  The RD's 190's were loaded at the top crimp groove but was not a compressed load.  Actually there was room for experimenting to take place.  No signs of pressure what so ever. 

  Anyway, I've been kicking around the idea of reaming this gun out to the 357 maximum.  But I got to thinking if I really needed to do that at all.  My brother had given me a bag of new maximum cases he no longer had use of.  So.....what I did was to take ten cases and trim them down to 1.440 inches and they dropped right into the 357 mag chamber.  This particular bullet design has two crimp grooves so I loaded a dummy cartridge using the top crimp groove for a OAL of 1.823 inches.  The round dropped right in so I loaded another round using the lower crimp groove for a OAL of 1.884 inches and it dropped in with no problem.  Even the longer OAL is not touching the lands.

So before I charge these loads up and start experimenting and testing, does anyone see any problems or danger I may headed into?  I know this will fall far short of the 357 maximum but I'm thinking 1900 fps or so with this 190 grain bullet should be attainable. 

[Dinny]

That's a shame what you're doing to that Maxi brass... trimming it and all... Have you thought about trying 360 Dan Wesson brass? It may be harder to find though, just kinda depends on the time of year and when the last batch was run at Starline.


If you like that, you'll like the Maxi even more.

Thanks, Dinny

[steve@357maximum.com]

This seems like a reasonable idea to me.  I have been contemplating doing something similar with a 45-70 case to make an Indiana deer hunting legal cartridge that will shoot out of a .45-70 just for kicks....no pun intended.  For safety sake, don't forget to use small rifle primers in your heavier loaded .357 Maximum shorties.  Also, since you are reducing the case capacity, you may have slightly higher pressures so keep a close eye on pressure signs.  Steve

[Spanky]

I think Stimpy tried a shortened 45-70 a while back and the results weren't great.



Spanky

[mike@nds]

The only problem I could see is if you pinch the case mouth in the throat and up the pressure.

Knowing the true dimensions of your chamber with a casting would be prudent.

I'd just ream it to Max and have a proper chamber for those types of heavier loads.

[Gohon]

Originally I had cut the brass to 1.460 and they chambered clean with no binding.  Knowing the that DW 360 brass was 1.415 I Took another .020 off the case for a final length of 1.440 which is just slightly longer than the 360 brass.  Since the case falls right in with no binding I'm sure the case mouth is not going to bind  or pinch in the throat.    First loads I make up which will be tonight, I'll be using Dan Wesson 360 load data and I'll work from there. 

If 360 brass was available I'd just buy that but Starline hasn't made any of the 360 brass this year and they say it is discontinued on back order until enough back orders make it worth their while to produce.  That may be next year and then again it may be two years from now.  The Maxi brass is available all over the place and it takes only a few seconds to cut each case down.   I suspect the maxi brass is also cheaper than special runs of 360 brass.  Anyway it really is an interesting project and should be fun to work with.  Most likely I'll end up reaming the gun to a maxi but in the mean time..................

[Dinny]

In my unmodified 357 Mag Handi, the 360 brass could chamber with no problems at all. Once I loaded it, the rounds would FTF. Tim suggested that I trim .010" off the brass and all my problems were solved. I still don't fully understand why that worked, but I am fine with it now that it works.  

Thanks, Dinny

[Gohon]

Just a quick update on my experiment.  Three separate five shot groups using 19 grains of Lil'Gun gave 1/2 inch groups at 50 yards at 1958 fps.  Actual bullet weight was 192 grains.  No signs of high pressure of any kind.  Still enough room in the shell for another grain or two without compressing the charge.  If these groups stay tight out to 100 yards which is the next step them this gun just became a easy 150 yard deer killer.  Now I'm wondering just what a good gas checked hard cast 158 grain bullet would do.

[Rustyinfla]

  It could be that the smaller groups are coming from the shortening of the gap from case to rifling. Good job. That's what careful loading is all about.

[gcrank1]

Have you found what the longest (bullet seated out) length is you can use? In a sgl. shot you dont have to crimp if the bullet 'pull' is OK in the case mouth and you might gain a little more boiler room.
Nothing wrong with your methodology and results that I see.