Pressure Testing various loads and crimps for 12 gauge

The bags of shot at the butt separate the recoil from my shoulder/surgery.


The pressure curves show little difference with the several crimps tested. In fact, the SD shown is 5 for the entire sequence of 10 rounds.









While the ammo was coned from 12 to 20 gauge, it's apparent that the reduction does not hold. In fact, the crimp opens a small amount in some coned ammo. The "0" refers to the factory crimp. The 3/8, 1/2, and 5/8 refers to the length of the coned area of the factory Rem Game Loads. The Rem Game Load factory and the 3/8 coned Rem Game Load data is in presented in the pressure curve data.

Note the descriptions of the rounds for the chart below are as follows: 1,2 Rem Game Load reference; 3,4 JTB reload "coned"; 5,6 JTB substitute Pyrodex; 7 JTB Pyrodex "coned"; 8 JTB Black Powder LIDU "coned"; 9,10 Rem Game Load Reference

Note the descriptions of the rounds for the chart BELOW are as follows: 1,2 Rem game load reference; 3,4 Rem game load reference "coned"; 5,6 Win AA Featherlite; 7,8 Win AA Featherlite "coned"; 9,10 JTB reload. The summary estimated pressure is meaningless as the ammo differs in the test.

The pressure is shown as peak, e.g. Round 1 Rem game load is shown as "92". This equates to 9.2 K Oehler pressure units. This assumes that theReference Remington Game Loads are at or below the SAAMI maximum for shotgun loads. Furthermore, all loads tested are substantially less than this reference.


Pictured below is the "strain gage" attachment to the test barrel.

I guess it's true that my posts on the SASSwire make it seem like I'm a maverick with regard to match transport of accessories and learning about reloading and posting my findings. Not to recommend anyone use my loads, the findings are just for information and hopefully of interest to those that log onto my blog. Since I'm recovering from heart surgery and the effect of shooting on my surgery is unknown, I intend to use lead shot bags to absorb the recoil rather than my body. Also, I don't intend to measure velocity, as the safety of reloads with regard to pressure is the objective of this study. My start date for actual firing rounds is March 6, 2008. the atmospheric conditions will be posted on the Oehler printouts.

The shotgun I intend to use for 12 gauge pressure testing is the H&R (NEF) 3" Magnum. Guess it's also called the Standard Handi/Pardner shotgun with a modified choke. Not the best choice as an open bore would be best as would a shorter barrel that more closely represents my Cowboy shotguns with about 20 inch barrels and 2 3/4 inch chambers. This shotgun uses a transfer bar safety along with an ejector. I'll attempt to find the proof pressure that this shotgun was tested for. A usual proof pressure for a standard 2 3/4 inch 12 gauge is 40K PSI.

The Strain gage is mounted 1" from the breech as recommended by the Oehler 43 instructions. Unfortunately, the epoxy on hand was out of date. While the strain gage checks electrically, it may not function properly if the epoxy loosens. Important to know that the Oehler PSI isn't absolute. It must be interpreted against a commercial load that is expected NOT to exceed the SAAMI standard.

I intend to use the Remington Game Load ammo that has 1290 fps and 1 oz of #7 1/2 shot. This load should have a higher pressure than the Winchester AA Featherlites with .26 grams of shot and a velocity of about 900 fps. The coned commercial load will be set to a depth of 3/8 inch that may approximate what was being used in SASS/CAS. Using a MEC Supersizer, 20 gauge to reduce the diameter of the 12 gauge factory crimp. The closest Lyman load data for the Game load has a velocity of 1205 fps and a pressure of 7000PSI. The Win AA Featherlite, according to the Hodgdon website has a maximum pressure of 5.6K PSI

My reload to be tested will list the hull. All have the Claybuster gray wad, 14.5 grains of American Select, and 7/8 ounce of # 7 1/2 shot. The coned reloads will be set to a depth of 3/8 inch. Again, the coned test will use the MEC 20 gauge Super Sizer to reduce the diameter of the 12 gauge crimp.

Another purpose is to fnd the effect of a deep folded crimp, 1/4 inch as compared to 1/8 inch. Both will have a strong Hornady Roll crimp to be comparible to the factory roll crimp.

A black powder load will also be tested and the specifications for the square load using LIDU and Pyrodex were tested with a few rounds.

Ammo........................ crimp ........ Oehler PSI......... Hodgdon PSI - Remarks

Rem Game load....... Fold ..............9.5K, 9.5K ........Unknown, but estimate 10.5K PSI Reference

Rem Game load....... Fold-cone.... 9.1K, 9.3K

Win AA FL................Fold.............. 4.1K, 3.8K......... 5.6K PSI from Hodgdon website

Win AA FL............... Fold-cone.... 5.8K, 5.7K

Rem Game Load..... Fold.............. 9.2K, 9.5K ........Unknown but estimate 10.5K PSI Reference

JTB Rem GL........... Fold.............. 3.8K, 4.0K........... Estimate to be like Win AA FL

JTB Rem Gl............ Fold-cone..... 4.2K, 3.8K

JTB Pyrodex.......... Fold............... 4.8K, 4.4K......... Square load 4.3 & 1 1/8 ounce shot

JTB Pyrodex.......... Fold-cone ......4.8K

JTB LIDU............... Fold-cone....... 4.2K

Rem Game Load.... Fold............... 9.3K, 10.1K .......Unknown but estimate 10.5 PSI Reference.

Keep in mind that these findings are only for my H&R/NEF 12 gauge 3" Mag shotgun. Findings for anyone elses guns may be compeltely different.