The Shotgun

[Tgace]

The Shotgun is one of the most powerful weapons in the self-defense arsenal. At the average range of a SD encounter, the power of this weapon is a force to be reckoned with. Its limitations being its size, which can limit its manuverability and ease of use by people of smaller size. Its recoil can be a factor, as can its limited ammo capacity and speed of reloading. However with the proper ammo selection and training anybody can operate the shotgun effectively.

There are two types of ammunition for defensive shotguns: buckshot and slugs. Birdshot...not even worth mentioning.
Contrary to popular belief, shotguns do not spread shot into such wide areas that they do not require aiming. If they did, that would make it negligent to use them in self defense situations. You are responsible for where your shots impact. Generally, buckshot leaving a shorter barreled shotgun will stay together for a little past one yard, after which it tends to spread approximately one inch per yard. This means that most shotguns wont be able to keep all the pellets of a standard 00 buck load on a stationary target, faced squarely, past 15 yards. It is wiser to assume that you probably can't keep all the pellets on your intended target past seven yards, especially under stress. It should also be obvious by this point that the shotgun requires aiming.

Magnum loads, which pack more pellets at higher velocity, tend to have greater spread. Which isnt really a good thing in a SD situation. "Tactical" loads, which have lower velocity than standard loads, often use hardened, plated shot and sometimes one pellet less, tend to have less spread. They also generate less recoil.

Because the 12 ga. is the traditional bore for police shotguns, it offers more options: more guns to choose from, more variety in ammunition, and more accessories.

Shotgun use in home defense is principally a short range, from cover affair. As such, I would stick to buckshot due to its less likelihood to overpenetrate. Slugs, in general, are for precision work and distance work. Since most homeowners wont be attempting to preform a hostage rescue with a shotgun, the first isnt much of an issue. If you are manning your homes defensive perimeter from alien attack then a rifle would be your better choice anyway.

Stick to pumps or autoloaders. Single shots, doubles and over/unders just plain run out too fast....

 

[Cruentus]

This is a good subject matter for me because I know very little about the shotgun; my focus has been on pistol first, and rifle second. I'll be sitting back and happily reading! :drinkbeer

 

[Tgace]

http://home.sprynet.com/~frfrog/shotgun.htm

The Zone System - While the use of sights will enable a target to be hit, a method is needed to help determine the optimum engagement distances for the ammunition used. The zone system sets up bands of weapon performance versus ammunition selection. The first or "A" zone extends from the muzzle to about seven yards, where the pattern has typically expanded to between four and seven inches. Within this range the shot charge is effectively a single projectile and it is quite easy to miss a human sized target unless sights are used.

The "B" zone extends from the end of the "A" zone to that range where charge of buckshot has spread to about the width of the human torso (about twenty inches). This occurs at a range of between twenty to thirty-five yards for most weapons. Since the shot charge is spreading out the pattern must be centered to effectively turn off an assailant. While hits can be obtained without proper sights, it is just as fast and much more positive to do it with sights. At the course that I attended the maximum range for the "B" zone for a given ammunition was determined by the range at which the shotgun would consistently knock down a 10 inch diameter steel lollipop target with the buckshot used. (One student's shotgun would consistently drop the target at 35 yards and about 50% of the time at 40 yards! That's patterning!)

Past end of the "B" zone, at twenty-five yards or so depending on the individual weapon, even with modern buffered loads and hardened buckshot the shot charge spreads so much that the majority of pellets may not strike the target that is aimed at. This area is called the "C" zone and this is where the rifled slug comes into play. At the course that I attended one of the techniques taught is a "select slug" drill that teaches the rapid switching to a slug round with a shotgun loaded with buckshot when a C zone target appears. While the approximate distances of the zones can be memorized, many of the students used the width of the thick ghost ring system front sight blade as a reference for the B/C break point but once practiced a couple of times you get a feel for when it's time to switch and it becomes automatic.

Some folks may comment at this point, "Why not just use slugs for everything and forget about buckshot" and some folks actually do that. Unfortunately, there are a couple of flies in the ointment with this approach. First, the use of buckshot is mandated by many organizations with slugs reserved for "special" use. Second, slugs will shoot clean through most soft targets so they must be employed carefully for general use.

The biggest problem with both buckshot and slugs is that their performance is highly individual weapon dependent, which brings us to the third principle.

Ammunition selection - Several noted gunsmiths who are familiar with shotguns have stated that the patterning or grouping ability of shotgun barrels is 1/10 gunsmithing and 9/10s magic. Barrels with effectively identical internal and external dimensions and chokes will give widely varying performances with different shot sizes, loadings, and brands. This is especially true with slugs where a barrel can show a three to five inch difference in group size simply by changing the brand of slugs.

Because the performance of a given barrel is so dependent on the particular ammunition trying to document patterning or group testing is a waste of time. However, using the same brand of standard 00 buckshot in a variety typical riotguns I have observed 25 yd patterns ranging from 4¾"(!) up to 25", and 5-shot slug groups using standard Foster type slugs ranging from slightly under 3" to over 5".

Some ammunition types such as the reduced velocity Federal and Remington "Tactical" buckshot loads generally give reduced pattern diameter in just about every weapon they are fired in because of the lower pellet deformation. However, there are always exceptions. Thus, it is extremely important to zero and pattern your shotgun with the actual ammunition that you will be using. This will allow you to determine the performance of and the appropriate zones for your combination.

 

[MA-Caver]

From the age of 10 to 16 I grew up outside a small speck on the map in Middle Tennessee and while this is far and beyond the fabled Hillbilly country the people were still share-cropping and moon-shining in certian parts.
The shotgun was the preferred weapon of the vicinity. Many of the shiners I gotten to know (in my early teens) did prefer the 00-buck shot but most of the time they had a far more effective deterrent... Rock Salt. The type used with hand-cranked ice-cream makers. A couple folks I knew did prefer bird-shot for their home defense. For the farmers it was mostly so they could use it against crows and other problem vermin. However; should they ever have to point their weapon at an intruder or trespasser, bird-shot would be less likely to kill, but when you think of the hundreds of pellets stuck in your *** and lower back that the doctor has to pull out...one by one, I'd hazard a guess that it would cause one to go into a state of reflection and find something else to do with their free time.
My first hunting experience (read: kill) was with the Shotgun. A .20 gauge single shot. Later moved up to the reliable .12 ga and had opportunities to shoot the awesome 16 ga. Killed several rabid animals at a safe distance too with my father's 20 and 12 gauges.
While sawed off versions of these weapons are illegal in most states (hell, all of them if I'm not mistaken) they were quite common among my friend's parents and were there primarily for the home defense for the fact that the typical long barrel of the weapon isn't there to be hampered by door jambs and furniture. It's also intimidating as hell, especially the stereotyped double barrel sawed off type.
Rarely though have I seen home-owners saw off the shoulder stock. "Ah mean, Ya'll gotta have sumpthin to brace the gun wit unner da ar'm wen ya's shootin it... t'ain't dat rite Billy Joe?" "A'yuh, dat rite dar Ralf." (Gads, I miss suthern speak... need to hang out with Seig, Tess and the rest o' de gang up dar in Wes Virginny.)
Anyway the shot gun is probably one of the most powerful and intimidating weapons anywhere. It's messy and very effective no matter what kind of shot you choose for it.

 

[Tgace]

I wouldnt recommend the "shoot em with rock salt or birdshot to teach em a lesson" tactic. If I have to shoot somebody its to protect life and that necessitates a quick resolution. Somebody just standing in my backyard "may" get a gun pointed at them, but Im not shooting them with anything unless the situation demands it....

 

[dearnis.com]

I wouldnt recommend the "shoot em with rock salt or birdshot to teach em a lesson" tactic.

Second that.

Biggest mistake made with the shotgun- assuming it is just point, shoot, automatically hit.... They are a wonderful, wonderful tool but you must put the time in getting familiar (and getting comfortable with recoil).

For social shotguns give very serious thought to upgraded sighting systems; there are several flavors of ghost ring sights on the market; done right they are fast, precise, and add tremendously to the weapon's versatility. Also some consideration to a weapon-mounted light source....

 

[Tgace]

Ya beat me to it!

Sights. In general, ghost ring systems are the best...

http://www.xssights.com/catshotgun.html

Red dots are nice, but I would hesitate to have a dedicated sight system that depends on glass and battery power.

 

[GAB]

Hi,

Regarding the birdshot being not worth mentioning...

When I was younger and hunted quite a bit, I also read quite a bit on the shotgun and its use in the brush and going in after a wounded animal especially wounded prey animals. ( I was a bowmaker and hunter in the middle sixtys) We had guys with shotguns as a back up.

One of the greatest African prey animal hunters recommended number sixes for backup when getting within a few feet of these animals and giving them the blast at a close range (5 feet). They go to the thick brush, same as boars. Then they charge when you get close.

Made sense to me. I saw a shooting where at about 5 feet the perp closed a door real quick, the hole in the door was about 4 " in diameter and the guy was hit in the buttocks. The damage is not just a hole it is missing material, as in flesh.

According to Hunter the animal receives all the foot pounds and at close range like that holes, as big as your fist in the brute.

He discovered this one time when he had accidently put the birdshot into his double barrel or had it as a back up, in one barrel. I believe it was a cat of some kind, big.. It was above him and the first shot (by the person hunting) just irritated the cat, it jumped from above and Hunter ( real name of guide)
hit the cat with the bird shot second round, flipped it in the air and it landed dead. Big hole in it.

Good story anyway.. I have experimented with it and it is deadly.

Regards, Gary

 

[Tgace]

If you have to be within 5' for it to be effective Id rather have buck. Its effective from 5' and out to 25 yards...KISS.

 

[MA-Caver]

I wouldnt recommend the "shoot em with rock salt or birdshot to teach em a lesson" tactic. If I have to shoot somebody its to protect life and that necessitates a quick resolution. Somebody just standing in my backyard "may" get a gun pointed at them, but Im not shooting them with anything unless the situation demands it....

Well neither would I... now-a-days. But consider what part of the country I'm coming from. Southern Baptists and Church of Christ church members being predominate along with a smattering of other "old-world" churches to boot. "Being the good Christians they are" ... killin' somebody don't sit right. So at a distance they knew bird-shot would cause the least amount of damage say at a range of 10-15 feet.
But also consider... if a person is IN your house in the middle of the night and you didn't invite him or know him, you and yours are the only house for say about 40-50 acres... you're gonna shoot... you better shoot. If you're lucky enough to intimidate them outta the house then you can shoot AT them while they're on the run... with bird shot it ain't gonna be dat bad if it were buck. Using rock salt.. .(mind you they're ground to small pellets, akin to bird-shot) it'll give 'em something to be mindful of. Not to mention it's a lot cheaper to buy especially if you're a share-cropper out in that area.
Share croppers don't exist anymore I don't think. I think they were called something else in the 60's/70's when I was growin up in that area but the concept is the same none the less. Those folks were usually poor... dirt poor.

 

[GAB]

If you have to be within 5' for it to be effective Id rather have buck. Its effective from 5' and out to 25 yards...KISS.

Sorry Tgace but I respectfully disagree...

The reason is, the result. It is the whole load of shot 100 plus pellets. One large hole and covers more mass at that distance, not just 9 or 12 hitting the item.

The idea is to wait till they get close. Or because you are in the brush and cannot see more then a few feet. This is a very special circumstance.

Slugs are even more iffy because they are only one item and not like a fist or softball hitting the same area at the same speed.

I see where you are coming from.
But I have had a little experience myself.
It is not always that easy as to say KISS.
But then I will figure that answer, from your lack of experience.

Regards, Gary

 

[KenpoTex]

I prefer, and load my 12 gauge with 00-buck for home defense. However, like GAB said, I definately respect the damage "birdshot" can do at close range. Several years ago I shot a raccoon from about 15 feet with a 16 gauge loaded with #8's. I hit him right in the chest (he was "treed") and the shot literally blew away a chunk the size of a grapefruit out of his chest/shoulder area (and threw him out of the tree). birdshot may not be "ideal" but I wouldn't hesitate to rely on it if that's what I had.

 

[Tgace]

Dont get me wrong, at a range of out to say 10 yd. max, birdshot (wouldnt go smaller than #6 shot) can be damn effective. But on the average, I would still say that birdshot will only work reliably against larger mammals at distances which are much too close for comfort to depend on it. If you want more pellets go down to #1/#4 buckshot. IMHO....If its all you have and its gonna be close, by all means use it .

Had a cop responding to a burgulary in progress call hit with birdshot in my area recently. He survived fortunately, but had to have a lot of pellets removed from his chest/shoulder...no big chunck blown out..this was from about 7-10 yards. Dont know the shot size.....I would just prefer to have the most flexable load possible regarding range. But like I said, if its all you have...

 

[Tgace]

http://home.sprynet.com/~frfrog/shotgun.htm

The Effectiveness Dilemma

At this point a brief discussion of small arms "effectiveness" is in order. When talking about the effectiveness of any small arms system, it should be noted that the military looks at effectiveness in a different light than the law enforcement or civilian user. The police officer or civilian is interested in the immediate termination of the actions of the individual shot—the proverbial "instant incapacitation." The military on the other hand is primarily interested in creating a wound that will require medical treatment and hopefully the use of several other enemy troops to help the individual who was hit.

Thus, the military considers that an effective hit is one that delivers approximately 58 foot pounds of energy to the target rather than one that instantly shuts down the target. While a shot pattern typically opens up about 1" per yard of range, a good riotgun with a load of #4, #1, or 00 buck can provide several, if marginal, hits on a full length human target out to about eighty yards at that range when directed with a good set of sights, but one does not get "instant incapacitation." If viewed in the military perspective the 12 gauge riotgun firing buckshot can be "effective" on individual targets at that range.

The table below shows the average results of firing at fifty and seventy-five yards at a full length human silhouette with #4, #1, 00, and 000 buck from cylinder bored, rifle sighted, riotgun. Note: most of the hits at 75 yards were very "marginal."

Loading Avg. Number of Hits
(Full sized humanoid target)
50 Yards 75 Yards
27 pellet 4 buck 10 3
34 pellet 4 buck 6 2
16 pellet 1 buck 6 2
20 pellet 1 buck 7 4
9 pellet 00 buck 3 1
12 pellet 00 buck 4 2
8 pellet 000 buck 1 0

Less anyone thinks that only one or two pellets of buckshot will effectively turn off an attacker, consider what is actually striking the target. A pellet of 00 buck is essentially a 54 grain, .33 caliber projectile that is traveling between 1000 and 1300 feet per second. This puts the effectiveness of each pellet of #4 buck at about the .22 rimfire level and 00 buckshot at the muzzle somewhere between that of the .32 ACP and .380 ACP cartridges, none of which any serious person will bet their life upon. The table below gives some interesting data.

Shot Size Pellet Diameter (in) Pellet Weight (gr) Sectional
Density Velocity (fps-20" bbl) Individual Energy (ft lb) Number of pellets in loading Total Weight (oz) Total Energy
(ft lb)
000 .36 70 .077 1265 250 8 in 2¾" 1.3 2,000
00 .33 54 .070 1295 200 9 in 2¾" 1.1 1,810
0 .32 48 .066 1200 155 12 in 2¾" 1.3 1,860
1 .30 40 .063 1215 130 16 in 2¾" 1.5 2.080
4 .24 20 .052 1260 70 27 in 2¾" 1.2 1,890
#6 Shot .11 1.9 .022 1290 7 280 in 2¾" 1.25 1,970
.32 ACP .31 71 .104 900 130 - - -
.380 ACP .35 90 .102 950 190 - - -
38SPL +P .35 158 .177 890 280 - - -

At 75 yards a 00 buck pellet is only traveling at about 830 f/s and has only about 85 ft lb of kinetic energy. At 100 yards the kinetic energy is about 70 ft lb. In addition, shot, because of its spherical shape (and thus low sectional density) has inherently poor penetration compared to a conventional bullet, especially if deformed by intervening material. (#4 buckshot is especially known for this problem.) The so-called "premium" buckshot loads with their hardened and/or plated pellets generally give better performance because the pellets don't deform as much.


--------------------------------------------------------------------------------

A Penetrating Study

To determine what kind of penetration could be expected the following data was obtained from various published and International Wound Ballistics Association (IWBA) sources. The #6 birdshot load of copper plated hardened shot (2¾" - 1¼ oz -3¼ Dram) that is often recommended as an ideal solution for the in-home scenario was fired at five yards to discover the effectiveness of that loading at in-house/across-the-room ranges. All other penetration data was obtained at seven yards. It is generally accepted by those involved in the wound ballistics field that a minimum penetration of twelve inches of 10 percent ordnance gelatin is one of the criteria needed to provide reliable incapacitation of a human assailant.

12 Gauge Penetration Tests
10% Gelatin
Load Number of Pellets Penetration
@ 7 yards
000 Buck 8 14" - 16"
00 Buck 9 13" - 15"
1 Buck 16 12" - 14"
#4 Buck 27 9" - 11"
#6 Shot (Hard shot) 280 4" - 6" (@5 yd)
1 oz Foster Slug - 18"
450 gr SABOT Slug - 21"

As can be seen from the table, the often recommended standard 4 buck load is lacking in penetration. This has been confirmed by data from numerous field experiences and is especially true if the target has any "give" to it such as a loosely fitted leather jacket. The #6 shot often recommended for home protection also gives marginal penetration. To insure adequate penetration under all conditions you should stick with 1 buck or larger shot although the #6 shot will probably suffice for the initial in-home encounter at "across the bed distances," where the shot charge is still essentially a single mass, when backed up by a buckshot round.

In addition, shot's spherical shape doesn't give a very good ballistic coefficient (00 buck has a nominal Gs coefficient of about .071 (approximately .045 G1) compared to .104 G1 for a 71 gr .32 caliber FMJ bullet or .390 for a 150 gr .30 caliber spitzer) and the velocity drops off rapidly as you can see below.

Performance of 00 Buckshot
Range Velocity
0 1290
50 1060
100 780

Since the shotgun with slugs is frequently used against "hard" targets penetration tests were done, using standard NATO steel test plates. Buckshot loads are shown for comparison and the results are given in the table below.

12 ga Penetration Tests
SAE 1010 .138" steel plate
Load 7 yd 25 yd
000 Buck N N
00 Buck N N
1 Buck N N
4 Buck N N
1 oz Foster Slug P D
450 gr Sabot Slug P P
P = Penetrated
D = Dented
N = No Effect


--------------------------------------------------------------------------------

Sluging It Out

Contrary to popular belief, the shotgun with conventional Foster slugs is not hopelessly inaccurate. The myth of the "inaccurate" slug probably got started by those individuals trying to hit a target with shotgun equipped with a front bead sight only. The average fighting shotgun, (eighteen to twenty inch cylinder bored barrel) using good ammunition and fitted with proper sights, can easily, group five shots into ten inches or less at 100 yards, and inside of four to five inches at fifty yards. While this is not tack driving performance it is more than adequate for use against human assailants or deer sized game out to 75 to 100 yards.

Most people think that the trajectory of the 12 gauge rifled slug is close to that of a mortar, and since they don't think they could hit anything past 25 or 50 yards (which is probably true if they don't have a set of sights on their shotgun) they zero for slugs at 25 yards. Unfortunately, this short zero severely limits the effectiveness of the slug firing shotgun. Surprisingly, a slug's trajectory is quite flat out to about 125 yards (assuming the proper zeroing range). The biggest limitation of the shotgun slug is that penetration and trajectory drop off drastically beyond 125 yards due to velocity loss, so its maximum effective range is probably about 125 yards. (I still wouldn't want to be hit by a slug at 200 yards though!)

12ga Foster Type Rifled Slug (G1 = .109)
(20" barreled riotgun with ghostring sights)

Range Velocity Zero = 75 Zero = 100
0 1440 -1.0 -1.0
25 1320 0.7 1.4
50 1200 1.1 2.5
75 1120 ± 2.1
100 1050 -2.8 ±
125 1000 -7.5 -4.0
150 960 -14.4 -10.2

A problem with slugs at the longer ranges is their reduced hard target penetration due to velocity drop and generally soft lead construction. However, even at 100+ yards they will take any opponent out of the fight unless they are behind heavy cover. During a course I attended students had no problem consistently hitting humanoid sized steel targets at ranges up to 100 yards. The resulting impact left no doubt that an assailant would have been deactivated.

The new saboted subcaliber slugs that have become popular can decrease group size when fired from a conventionally bored shotgun that likes them, and they offer increased penetration at the longer ranges. However, they are really designed for use in shotguns with rifled choke tubes or fully rifled barrels. Fired from weapons so configured, 100 yard five-shot groups of four inches or less are quite common. Unfortunately the rifling plays havoc with the patterning of buckshot. One problem commonly reported with the saboted slugs, especially in a smooth barrel is that about ten percent of the time the sabot fails to separate cleanly causing a really wide flyer.

 

[modarnis]

On the issue of shot size:

Don't forget that most humans wear clothing. Now that it is winter, heavier clothing severely limits penetration of birdshot. I will use a hunting analogy, you use larger bb, #1 or #2 shot for geese for the same reason, they have a couple inches of down and an inch of fat, all which dissipate the force of the shot.

Unlike a rifle bullet or a slug, the shot stream is somewhat conical as it leaves the barrel and expands. Pellets on the outer edges of this cone lose velocity and drop off. You may break a clay target with one of these dropoffs, but in all likliehood not get the self defenseresult desired.

A good method to test your load/choke combo is o pattern the shotgun. A large piece of whit posterboard with a black dot in the middle will suffice. Use a 15-20 yard distance. After you shoot the target once, draw a 30 inch circle around the pattern hit. Knowing the shot size and load (1 oz, 1 1/18 etc you can know the # of pellets started with) figure the percentage hit in that circle.

Absent a ghost ring sight system, shotgun mount is critical. Without a sight system, if you mount the gun differently, its like a moveable rear sight. Us skeet shooters say head on the gun and eye on the target. You can observe the effects of mismounts on the pattern board as well.

A great, user friendly home defense 12ga with ghost ring sights is the Benelli Nova. Out of the box under $250. For an extra hundred you can add a mercury recoil reducer and a magazine extender with 2 3/4 shells will give you 7+1. Add another $180 and you can get a 26 or 28" barrel that allows you to convert it to a nice waterfowling gun too

 

[dubljay]

Not to discount the effectiveness of shooting a person at 5 feet with any kind of shotgun load, but in my opinion in a self defense situation, if you let them get with in 5 feet of you... you messed up. Granted you get taken by surprise and *pow* no doubt of the result should you hit them, however should I be facing some one I sure as hell wouldn't let them advance within 10 feet of me. There is a slim possibility that they could be on top of you before you could get a shot off.

 

[TonyM.]

The chart was really aimed at waterfowlers because it showed a greater hit average with smaller pellets. Anyone shooting at anything over fifty pounds at seventy five yards with anything other than a rifled slug or preferably a sabot would be very foolish in my opinion anyway. On the other hand home defence shooting is usually in less than twenty feet indoors. BB or one of the smaller buckshots are plenty of oompf at that range without killing your family or neighbors.

 

[GAB]

The chart was really aimed at waterfowlers because it showed a greater hit average with smaller pellets. Anyone shooting at anything over fifty pounds at seventy five yards with anything other than a rifled slug or preferably a sabot would be very foolish in my opinion anyway. On the other hand home defence shooting is usually in less than twenty feet indoors. BB or one of the smaller buckshots are plenty of oompf at that range without killing your family or neighbors.

Hi all,

I have to agree with all the information you are putting forth, good stuff, thanks.

In a house the distance is very close, just think about it. Most shootings are at close range. They should be if you think about it for any length of time.

There is a real disadvantage to the shotgun, very powerful and deadly to say the least. Many times they are just in the way. Given that statement, I still feel like Tgace does. I only threw the birdshot in for conversation sake.

Not to blow my own horn but being a very good shot helps to give one confidence and in that arena you are king when it comes down to precise shooting, it is the main factor in confrontation.

Scatter gun ment just that... Not the best in a crowded location or for the novice...It is like bringing in the cannons or howitzer in my opinion.

We relied on it very much in my days on the force, every man had his own individual one and carried it next to him in the vehicle, it is very effective in close quarters, butt stroke and all, just look at it as a four foot baton.

Regards, Gary

 

[psi_radar]

Dont get me wrong, at a range of out to say 10 yd. max, birdshot (wouldnt go smaller than #6 shot) can be damn effective. But on the average, I would still say that birdshot will only work reliably against larger mammals at distances which are much too close for comfort to depend on it. If you want more pellets go down to #1/#4 buckshot. IMHO....If its all you have and its gonna be close, by all means use it .

Had a cop responding to a burgulary in progress call hit with birdshot in my area recently. He survived fortunately, but had to have a lot of pellets removed from his chest/shoulder...no big chunck blown out..this was from about 7-10 yards. Dont know the shot size.....I would just prefer to have the most flexable load possible regarding range. But like I said, if its all you have...

I keep birdshot in my short-barreled Ithaca 12 gauge. I've measured the possible shot paths within my home, and the longest would be 12 yards. The old Ithaca I have has the neat feature of being able to fire as fast as you can pump while holding the trigger down. So I can get some lead downrange real fast. I know the birdshot won't have the same sort of penetration, but that's ok with me since I'd prefer the shot not to be able to slip through walls or doors and hit anyone it shouldn't.

 

[Tgace]

The chart was really aimed at waterfowlers because it showed a greater hit average with smaller pellets. Anyone shooting at anything over fifty pounds at seventy five yards with anything other than a rifled slug or preferably a sabot would be very foolish in my opinion anyway. On the other hand home defence shooting is usually in less than twenty feet indoors. BB or one of the smaller buckshots are plenty of oompf at that range without killing your family or neighbors.

The chart was entirely aimed at military and LEO use. The result was purely mathematical. Of course more pellets are going to result in more hits at range while taking spread into account. The problem is how effective are those hits? The study, if anything, is pro-slug as the author points out that buckshot beyond its intended range is a poor penetrator.As Gary points out, the shotgun is an aimed weapon. Shot patterns are only inches across at "social" ranges. A slug could work just as well, the problem is overpenetration. As shot deforms and looses velocity much easier, its better for indoor use.