Jack D. Davis, Metalsmith, retired

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.357 Magnum Single Shot Rifle

SAAMI chamber with the long throat/forcing cone

The Rifle

Recently, I purchased a used (Like new) H&R Handi Rifle in .357 magnum caliber at Cabela's and, after a few rounds to make sure it shoots, I started to work on it.

The objective was to make it as short as possible for stowing in my camper. A fun gun, survival gun and occasional hunting gun.

First, I cut the barrel off to 16.5", then I removed the scope base and replaced it with a 12" Pickatinney rail. I then mounted a Weaver 4X scout scope using QD rings. I also mounted a Bushnell Red Dot, also using QD rings. Then I mounted a laser under the barrel forward of the forearm.

Plans are to take the scope base that came with the rifle, cut it down some and mount it on the forearm behind the sling swivel mount for other accessories (bipod, tactical flashlight). I replaced the recoil pad with a butt plate (not shown) and now the rifle is just 31-1/8" OA long.

Added the cut-off section of scope rail to the forearm and fabricated a ridged bipod for bench shooting. A pair of UTG QD rings for easy on/off.

Changed scope to Bushnell 3-9X40mm with 6" eye relief on 1/2" riser. I've removed the laser and will reinstall on the picatinney rail on a side 45 degree mount (ordered). A light is coming for the forearm rail.

 

 

Laser moved to picatinney rail on offset 45 degree and weapon light mounted to forearm rail.

Weapon light removed and bi-pod installed.

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The Loads

As always, DO NOT USE THESE LOADS without backing off 10% and working up according to safe loading techniques. I consider them to be safe in my firearm, but not necessarily in yours.

After some testing, I learned that this rifle had an extra long throat. So long, in fact, that the bullet jump from a standard 1.6" cartridge was almost 1/2". I don't know why this is such a long throat/forcing cone, but I have learned it is the SAAMI standard chamber. It is what it is and because it is, I can use that long throat to my advantage.

Being a single shot rifle, I am not constrained by such things as cartridge overall length to fit in revolver cylinders or lever gun actions. Also, since it is a single shot, there is no need to crimp into a cannelure. This means that I can seat bullets much shallower and that not only gets the bullet closer to the rifling lands, it also allows room for more powder. With some of the heavier (180 gr. and 200 gr. and up) bullets, you can equal published loads for the .357 Maximum in the magnum (1.285") case in single shot rifles with the long throat found in some Handi rifles and perhaps others, too.

The Powley computer online is found at Powley Computer

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Hornady 140 gr. FTX

I received a box of Hornady 140 gr. FTX bullets as a gift and went to work working up a load using this bullet. I seated a bullet in a case as shallow as possible then chambered it and slowly closed the chamber, allowing the riflings to push the bullet into the case. Extracting the case, I learned the COL with this bullet touching the lands was 1.96". But it was just seated about 1/8". Workable, perhaps, but I felt deeper was better. I decided on 1.86" COL with the bullet seated ~.22". It was nice and firm.

I had some IMR 4227 on hand, so starting at 16 gr. I loaded and fired one. No signs of excess pressure. Then I moved up to 17 gr.. Still no signs of excess pressure. 18 gr. 19 gr. then 20 gr. Still no signs of excess pressure. The 20 grain load was compressed, so this is the maximum load possible in a magnum case with the COL at 1.86". I don't have a chronograph, but calculating and estimating MV based on published loads in the .357 Maximum, and adjusting for barrel length and added powder, I believe it is in the area of 2050 fps. I have since fired a number of these loads with no pressure problems in my rifle.

Loads specifics as follows:

bullet

Case trimmed to 1.285"

bullet

Powder IMR 4227, 20 grains, compressed

bullet

Bullet Hornady 140 gr. FTX

bullet

Cartridge OAL (COL) 1.86"

bullet

Primer CCI 500 (small pistol)

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Hornady 200 gr. FTX

Next I purchased a box of Hornady 200 grain FTX bullets, and following the same procedures, I arrived at a COL of 2.25" with the bullet touching the lands and seated deeper to 2.15" for my COL. This also gives me a seated depth of ~.22". Again starting at 16 grains of IMR4227 and going up to 18.5 grains before seeing a flattened primer, I consider 18 grains to be maximum in my rifle. 18 grains of IMR4227 is the listed maximum load for the .357 Remington Maximum (.357 Super Mag.) I then settled on 16.7 grains because this is the nearest charge my powder measure throws without going over 18 grains. Actually the next measure aperture up throws 20 grains of 4227. I'm guessing that this load is in the area of 1650 fps. But that is really a WAG. Could be more, could be less.

Load specifics:

bullet

Case trimmed to 1.285"

bullet

Powder IMR 4227, 16.7 grains

bullet

Bullet Hornady 200 grain FTX

bullet

Cartridge OAL (COL) 2.15"

bullet

Primer CCI 400 (small rifle)

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Hornady 158 XTP

I couldn't touch the lands with the Hornady 158 gr. XTP in the magnum case. I ended up with a COL of 1.75" and a maximum charge of 20 gr. IMR 4227 powder. MV ~1900 fps. Test firing shows no signs of excess pressure. This charge is slightly compressed and would be maximum in a magnum case, but a bit below maximum pressure for the COL and my rifle. MV ~1900 fps.

Load specifics:

bullet

Case OAL 1.285

bullet

Powder, IMR 4227, 20 gr.

bullet

bullet, Hornady 158 gr. XTP 

bullet

Primer CCI400 SRP

bullet

COL, 1.75" 

 

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Hornady 180 gr. XTP

This load is near maximum, but shows no excess pressure signs in my rifle. Again the powder is slightly compressed at 20 grains. COL of 1.85". MV estimated to be near 1900 fps. This (20 gr. IMR 4227) is the listed maximum load for the .357 Remington Maximum (.357 Super Magnum) on the Hodgdon website.

Load specifics:

bullet

Case OA length 1.285"

bullet

Powder, IMR 4227, 20 gr. 

bullet

Bullet, Hornady 180 gr. XTP

bullet

Primer, CCI400 SRP

bullet

COL, 1.85" 

 

 

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My favorite plinking/target load for revolver and rifle:

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.38 spl or .357 mag case

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148 gr. hollow base wad cutter

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3 gr. to 3.5 gr. Trailboss

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CCI500 primer

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Typical Comparison of Magnum and Maximum in these loads

Standard length 1.60" COL, 1.86" length COL, 2.15" COL

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Test Firing

4/28/12    Today, my son and I took our rifles and handguns into the nearby woods for some shooting fun. This is the first time I had a chance to try the above Maxi loads in magnum cases at longer ranges. We were shooting at around 125 yards over the hood of his car and standing off hand. Both loads are quite accurate. I was able to hit small rocks and sticks measuring ~6" regularly at this range. More than enough accuracy for hunting and plinking. I fired 45 rounds of the 140 gr. FTX load and 50 rounds of the 200 gr. FTX load. None showed any signs of excess pressure. Primers and cases look normal and they extracted easily. In short, the bullets went where I was pointing at the time it fired. Next time, I hope to have a bench rest for fine tuning.

 

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Last modified: March 03, 2013