357 SIG Long Neck

[my_old_glock]

I am working on a long neck 357 SIG cartridge. It has the same dimensions as the regular 357 SIG from the taper/bevel to the base, but has a longer neck so I can use cast bullets with wax/lube rings. It uses standard 10mm brass, and will have an overall length of ~1.260" (same as 45ACP and 10mm).

Using Quickloads software it looks like I can get the same velocity from my Glock 20 using a 158gr lead bullet in this 357 SLN cartridge as a I can with a 4" 357 Magnum revolver with the same bullet in a 357 Magnum cartridge.

Here is a picture of a mock-up using an old (damaged) 10mm case. It isn't perfect. I just wanted to see what it looked like. I have to machine my 357 SIG sizing die and crimper to make it work, as well as rechamber my Lone Wolf G20 barrel.






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[my_old_glock]

Maybe I will call it the 357 Kayan after the the long necked Kayan People.




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[Blades]

Is it like the 9x25 Dillion? Although I don't know if the 9x25 can use a 158 grain bullet. Just wondering.

[fltbed]

You should call it the 9X25 Almost.

As in, it's Almost a 9X25 Dillon

[The_Shadow]

I use cast Bullets in my standard 357 Sig and 9x25 Dillon cartridges.  Neck tension is a key to bullet fit without loose bullet fit.
I'm using the dillon dies for both after the LEE 357Sig sizer started marking / galling the brass.

I use my RCBS 9mm expander die to do the neck so I do get the advantage of the longer straight section and flair only enough to accept the bullet base.  Seating is done slowly via a separate step to provide a straighter bullet positioning.  They I add the taper crimp to finish things.

My cast bullets are sized to 0.3565".  I have shot some 0.357" jacketed as well

[The_Shadow]

my_old_glock, One thing that concerns me with the long neck is that the case will enter the freebore area and not be allowed to expand putting extra drag/friction on the bullet that may increase the pressure spike and/or possibly resize the bullet smaller which might give leading and poor accuracy...Just some observations for thought.

[my_old_glock]

my_old_glock, One thing that concerns me with the long neck is that the case will enter the freebore area and not be allowed to expand putting extra drag/friction on the bullet that may increase the pressure spike and/or possibly resize the bullet smaller which might give leading and poor accuracy...Just some observations for thought.

I don't think I understand what you are saying.

I plan to use my 9x23 chamber reamer to make the necked down part of the barrel's chamber longer. I know the 9x23 is taperd, and the 357 SIG is straight, but I doubt it will make much difference.


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[The_Shadow]

OK, I was just wondering if you were going to shoot these from a standard 357Sig chamber, where the extra neck would protrude into the trueing cone area where the bullet would try to force itself out and over the extended neck section, but if you are modifying that area, you may be just fine.

[my_old_glock]

I modified my sizing die, and formed some more old 10mm brass. The crease you see about halfway down the side was caused by the 357 SIG die because the used 10mm brass was bulged. [It was the same brass I used to test the 210gr XTP 41 mag bullets in this thread (post #48) http://10mm-firearms.com/reloading-10mm-ammo/41-magnum-bullets-in-a-10mm/48/ ] I resized in 3 steps. The line was made after the 2nd step. I then ran the 10mm brass through a LEE buldge buster die. I than finished the last step. They are not perfect, but should work OK for testing.

[my_old_glock]

[my_old_glock]

I was able to run these past a chronograph. (I did not shoot the one on the far right - #6)

All were shot from a Lone Neck modified 6" Lone Wolf barrel.


Frome Left to Right is:

Standard 357 SIG.
Sig Sauer 357SIG brass
Berry's 124 grain HBFPTP
10.0gr 800X
COAL 1.150"
Velocity = 1660 fps  (over the 1500 fps recommended by Berry's)

Notes: This cartridge was not as precise out of the Long Neck chamber as it was from the same barrel before I reamed the neck longer. The extra gap or free travel may have been the culprit.

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357 SIG extended length or long seat.
Sig Sauer 357SIG brass
Berry's 124 grain HBFPTP
11.2gr 800X
COAL 1.260"
Velocity = 1755 fps  (over the 1500 fps recommended by Berry's)

Notes: Precision was about the same as the standard 357SIG ammo tested above.

*******

357 SIG Long Neck.
Sig Sauer 10mm brass
Berry's 124 grain HBFPTP
12.5gr 800X
COAL 1.260"
Velocity = 1830 fps  (over the 1500 fps recomended by Berry's)

Notes: This is a hot round. I do not know why I used 12.5 grains with this load, and only 11.2 grains with the previous load. I thought I made them the same. This looks faster than Underwood's 125gr FMJ 9x25 Dillon load, but I do not know if their stated velocity is out of a 6" barrel - like this cartridge/load.

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357 SIG Long Neck
Sig Sauer 10mm brass
Lee 358-158-RF cast lead bullet mold (actual weight was 165gr)
8.7gr 800X
COAL 1.250"
Velocity = 1450 fps

Notes: This was the most precise of all the loads I tested. This load is equivalent in velocity to Buffalo Bore 158gr 357 load out of a 4" revolver (according to the Wikipedia page for the 357 magnum cartridge). A 4" barrel revolver is close to the same overall length as a Glock 20 with a 6" barrel and slide.

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357 SIG Long Neck
Sig Sauer 10mm brass
Lee C358-158-SWC cast lead bullet mold (actual weight was 165gr)
8.2gr 800X
COAL 1.250"
Velocity = 1375 fps

Notes: I was not impressed with this cast bullet. It had the gas check installed but the check was below the neckline, so it might have come loose and shifted when the cartridge was fired causing out of balance and poor precision. I did not find any gas checks between the gun and target, nor were there any gas check holes in the target.

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This cartridge has potential.

All primers look relatively the same in flatness and firing pin slot spooge over. The only real difference is that small primers were used in the 357 SIG brass, and large primers were used in the (modified) 10mm brass. There was no case bulging with any loads.



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[Rorge Retson]

Any updates on this??

[my_old_glock]

Any updates on this??

I have not had time to shoot these again.

It will probably be another 6 months until I can post something worthwhile.

I am planning on trying some (resized) Hornady XTP and FTX 140 grain 357 magnum bullets.



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[asilcot10]

Any updates on this??

I have not had time to shoot these again.

It will probably be another 6 months until I can post something worthwhile.

I am planning on trying some (resized) Hornady XTP and FTX 140 grain 357 magnum bullets.



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Wishing you a speedy recovery.

[Neal]

I know this is an old thread, but I just found it. Of all the wildcat bottleneck pistol cartridges, this one interests me the most. The weak link in my two favorite bottlenecks, the 357 SIG and the 400 CorBon, is the short necks. Also had a 9X25 Dillon barrel and Dillon dies several years ago. Sold my barrel to McNett, and the dies to a Glock Talk forum member. It was fun to play with, but had limited practicality. As a lover of cast bullets, this long neck cartridge fascinates me and I wonder if the OP has done any more load development with it.