I've been experimenting recently with two-projectile loads in a snubby for self-defense. I'm wondering who else has given this serious thought.
Here are some combinations I've tried:
Attachment 238451
(1) Lee 356-95 RF base-to-base with 105 grain H&G #50 = 200 grains
(2) Lyman 356402 base-to-base with NOE 70 grain WC = 195 grains
(3) Two Lee 356-95 RF base-to-base = 190 grains
(4) Two Lyman 356404 base-to-base = 190 grains
(5) Lee 356-95 RF base-to-base with NOE 70 grain WC = 165 grains
(6) Two NOE 70 grain WC base-to-base = 140 grains
(7) One 000 buckshot over NOE 70 grain WC = 140 grains
I've been using 2400 powder for the 190 - 200 grain loads with velocities about 750 ft/s with easy extraction and no serious flattening of primers. I've flirted with 4756 for the 140 grain loads with velocities approaching 1000 ft/s but I don't like it. I won't list any specific loads and caution anyone first trying something like this that the bullets are probably going to be seated deeper than a single bullet of the same weight, so even published loads might give excessive pressure.
With everything I've tried, accuracy at 7 to 10 yards has proven more than adequate for the purpose. So my bigger concern has been penetration. Early on, i was relying on Hatcher's energy-based formula for penetration through 7/8" pine boards. That's what (mis)led me to the 140 grain combinations at high velocities and I won't admit how much time I wasted trying to determine a useful R (for resistance) value for ballistic gel. Then I finally broke down and bought the kindle version of MacPherson's
Bullet Penetration book. From MacPherson I learned (what I should have already known) that penetration depends more on sectional density than energy.
Both MacPherson's graphs and the "expedient equation" from Schwartz's
Quantitative Ammunition Selection show that the 190 to 200 grain combinations at, say, 750 ft/s, should exceed the 12" FBI minimum penetration standards in bare gel. So far, my actual penetration testing has been limited to a few shots into some homemade (uncalibrated) gelatin and a couple shots into a fresh brick of Clear Ballistic gel. With the homemade gelatin, three shots of the #3 combination -- two Lee 356-95 RF bullets loaded back-to-back at about 750 ft/s -- coasted through a 14" brick of uncalibrated gel proving absolutely nothing.
To date, I've only fired two shots (#1 combination -- Lee 356-95 over 105 grain H&G #50 WC at about 750 ft/s) into a 16" brick of calibrated Clear Ballistic gel. The results were at least thought-provoking. Both MacPherson and Schwartz predict the front bullets should penetrate over 16" and the back WCs about 13-14". Surprisingly, all four bullets penetrated the full 16". More testing awaits the construction of a mould to re-melt the gel.
Now, I suppose the obvious question is "Why bother?" One answer is that I accept the "Shot placement is King and penetration is Queen" mantra. But to that I would add "Lady Luck is the Court Jester." Given good shot placement and adequate penetration, whether any given bullet hits a vital target and immediately ends the threat is very much a matter of luck. And if I'm shooting at the Fitz Luck Target, I figure I have a much better chance of a winning score with two shots rather than one.
But another answer to "Why bother?" has to do with what I call the "Hamburger Factor." There seems to be some consensus that the mass of tissue crushed in the permanent cavity is a reasonable measure of wound trauma. Given full penetration of a non-expanding and non-tumbling bullet, MacPherson sets this wound mass for a .38 at 24 grams for a wadcutter and 16 grams for any other bullet nose shape. The corresponding numbers for a .45 would be 39 grams and 26 grams.
So, if both bullets from combination #1 really will reliably penetrate more that 16" of ballistic gel. That would indicate a wound mass of about 40 grams per shot and put a cylinder full from a 2" snubby on a par with a magazine full of GI hardball from a 1911.
Now, I understand that there's a lot of hand-waving involved in this with graphs and equations and theories. But 200 grains of lead at 750 ft/s is nothing to scoff at and two .36 caliber holes are bigger than one .45 caliber hole and two shots at the Fitz Luck Target will usually out-score one shot. So, if I can convince myself that the back wadcutter will reliably penetrate 16" of gel, I think I'll become a believer.