Tackling this from the opposite side of the fence. My personal range ammo tends to be lead bullets and fast powders (Titegroup). This gives me accurate, inexpensive, low recoil, pretty clean, target loads, in .38 and .44. To reload a premium grade SD load, I would be looking at buying a slower powder (like CFE Pistol), for this load only, and a hundred count box of XTP or Gold Dot. The cost would be much more than what I would be paying just buying a 20 or 25 count box of any well-regarded SD load, and even shipping from Lucky Gunner.
No, on cost grounds, I don't think this makes sense.
I don't agree with your assessment at all, from both effectiveness and cost perspectives.
In terms of effectiveness, I've had conversations like this before. They go something like this:
Me:"How long is that 25 round box of self defense ammo going to last?"
The other guy: "I just plan to carry it and never actually shoot it, unless you know, I need to in self defense"
Me: "So if you ever need to shoot in self defense, you are comfortable carrying and shooting self defense ammunition without ever verifying that it is reliable and performs well in your handgun?"
The other guy: "Well, it has great reviews...."
Me: How about practicing with your self defense load?"
The other guy: "We're at the range right? I practice every couple weeks with target loads.".
Me: "Do they have the same recoil impulse and point of impact as your self defense load?
The other guy: Well, no..."
Me: are you confident that you'll shoot your self defense loads as well as your target loads? Remember that you'll devolve to your lowest level of fully mastered training under extreme stress, and now you're adding ammunition that recoils differently and shoots to a different point of aim, on top of any other training shortfalls you may have."
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Using a single box of 25 rounds of premium self defense ammo might be a valid strategy if your "personal range ammo" has an almost identical recoil impulse, shoots to the same general point of aim. Some police departments do the same thing - issue a premium self defense hollow point for officers to carry, and then use a less expensive practice load that uses a load with the same point shape, weight, velocity and point of impact. But even then, the Department has usually tested the self defense load extensively in its issue handgun model(s), and the officers still usually qualify with the actual self defense load.
If you personally are shooting a semi-auto pistol, you need ensure that your practice load has the same point shape as your self defense load, is 100% reliable and demonstrates no set back issues in your pistol over at least 200 rounds of testing.
Even with a revolver you'll want to fire enough of your self defense rounds to ensure that the bullets don't back out under recoil (especially the last one or two) which could cause them to jam the cylinder and, worst case, also prevent a reload. You'll also want to ensure that the load doesn't create comparatively large pieces of unburned powder residue that might find it's way under the ejector star. Perhaps most importantly you'll need to confirm that the load isn't prone to light strikes in your revolver. You're probably looking at 50 rounds to meet that criteria.
So you're now looking at 3 boxes of 25 rounds, or around $75, for a revolver and around 9 boxes at around $225 for a pistol - if you want the assurance that it will function reliably.
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If you are using a fast powder and a lead bullet, that probably means a lower velocity target load, and it's unlikely to have the same recoil impulse, shoot to the same point of aim, or demonstrate the back out or set back characteristics in your handgun. That seriously degrades the value of your practice time.
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Let's look at my .357 Magnum hand loaded "self defense" loads. I'm using a Hornady 125 gr XTP on top of 9 grains of Unique that produces 1,300 fps in my 2 1/2" revolver (S&W 686+).
At that velocity the 125 gr XTPs give very reliable expansion along with penetration between 16" and 17" in ballistic gel, so the terminal ballistics are fine by FBI standards for expansion and penetration.
The recoil is much lighter with the 9 gr charge as compared to 20-21 grains of a colloidal ball powder like Win 296/H110 and I'm not losing any velocity compared to the slower burning powder, so I'm one up on most factory loads using similar slow burning powders optimized for 4" or 6" barrels.
Cost wise:
I pay $21.00 per 100 locally, or $17.40 per 100 plus shipping from Midsouth. One box or five boxes, shipping is the same at $10, so on line at five boxes per order, I'm paying $19 per 100. We'll use that for 19 cents per bullet.
I pay $22.00 per pound for Unique in a 1 pound can. I usually buy in 8 pound kegs at $150 or so for a cost of around $18.75 per pound but we'll use the $22 per pound cost. With a 9 grain charge that works out to 775 loads per pound, and 2.8 cents per load.
Primers cost me $31.00 per thousand at the local gun shows every 2-3 months, or 3.1 cents each.
I can get new Starline .357 Magnum brass for $89 per 500, or certified once fired cleaned and polished R-P .357 Magnum brass for $68 per 500. That's 17.8 cents per case for new brass, or 13.6 cents per case for certified once fired brass (which is just as reliable as new brass). I get at least 10 shots in a case before it has to be retired, so we'll estimate the reload brass cost at 1.8 cents per shot.
Consequently, my .357 Magnum loads used for practice in multiple fired cases cost me 26.7 cents per round, while my .357 Magnum loads in new brass cost me 42.7 cents each in new brass and 38.5 cents each in certified once fired brass.
In terms of costs for a box of 25 those per round figures equate to $6.68 per box in multiple reloaded brass, $9.63 in once fired brass and $10.68 in new brass.
I'll quite often buy Federal American Eagle or Federal Champion 158 gr JSP factory ammo when I find it locally in the $25 per box of 50 range as it shoots really well in my .357 lever guns and is a good hunting load. Then I'll use that once fired brass for my .357 Magnum revolver loads. At 50 cents per round, it's not much more expensive than my new brass .357 Magnum loads, but I count the once fired case as a freebee.
The end result is that for $75, I can shoot between 7 and 11.2 boxes of 25 rounds each - compared to just 3 or 4 boxes of 25 self defense loads.
That means:
1) I can afford to thoroughly test my "self defense" ammo;
2) I can afford to practice with it on a regular basis;
3) which makes it my "regular .357 Magnum range hand load", not a sounds-worse-in-court "self defense handload";
4) and also means I will shoot it much better if a self defense situation ever arises (unlikely, but confidence inspiring);
5) I can afford to cycle out my concealed carry ammo every range session so it's always fresh and not in fact the rattiest, dirtiest, most abused ammo I own, which is also confidence inspiring; and
6) each range session I am verifying that the load performs well in my handgun and that I shoot it well in my handgun, which is again confidence inspiring.
