Smoothbore Surprises

By olegv published on in Ammunition, Firearms

Conventional wisdom of defensive shotgunning says that larger projectiles penetrate more. So loading birdshot guarantees absence of overpentration, while slugs will sail through the foe and possibly hit bystanders. But shotguns are sometimes unpredictable, and this theory only holds “all other things being equal” which they seldom do.

Test firing results

Test firing results

This particular 20ga shotgun was loaded with the assumption that minimum penetration would be ideal for home defense. Should birdshot prove inadequate, #3 buck (the largest commonly available in 20ga) would come up, and then slugs. The gun was test fired earlier at 25 yards and penetration was found as expected: minimal for birdshot, moderate for buck and considerable for slug. This time, test firing was done at 7 yards picked as the more likely in-house distance and the results were quite surprising.

20ga rifled slug fired into gelatin

20ga rifled slug fired into gelatin

Slug sailed right through the tabletop used as the test material: veneer-covered particle board doesn’t stop much. The worry that slugs would also overpentrate on humans was laid to rest by firing them into gelatin: only about 7 inches of penetration were achieved, with massive fragmentation of the projectile. That shouldn’t have come as a surprise, as the rifled slug is thimble-shaped and made of soft lead. For deeper penetration, either Brenneke hard cast lead, sabot copper or DDupleks steel slugs would be required. But slugs with deeper penetration are probably not the default home defense munition.

Buckshot was next. Spread was as expected, roughly XX inches. The pellets penetrated the tabletop but had little energy left on the other end. #3 buck pellets are about quarter inch in diameter, weigh just under 24 grains and have initial velocity of about 1200fps. That’s similar in energy to .22 Short bullets but with lower sectional density and no stabilization through rotation. The load makes up for the low individual pellet energy by launching about twenty projectiles at once.

The surprise of the day was delivered by birdshot. Plain, soft bulk pack birdshot produced a smaller pattern than buckshot and greater penetration as well. That became possible because the wad cup stayed with the pellets at the point of impact and the entire assembly hit as a solid mass. By 25 yard mark, the wad would have separated fully, but up close birtshot worked as a large pre-fragmented slug. Penetration beyond the barrier was low, but the initial punch was much out of proportion to the expectations. The shots were fired from cylinder bore and they may have contributed to the tight pattern. Although choke tightens patterns of loose shot, it could have separated the wad from the shot quicker than the unconstricted bore. Given the unpredictable nature of barrel and load interactions with shotguns, the only way you would know for sure if your own weapon duplicates this result would be by conducting a test firing of your own.

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Comments (10)

  • Azbearhuntr

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    A gut shot at 21 feet will always disable?! Jesus where are you getting your info man?! I guess we can stop aiming for the chest then! I guess all those confirmed cases of criminals taking multiple hits in the vitals and not dropping are lies. Go ahead and load up your shotgun with shells made for 12 ounce birds and aim for the gut…wow.

    Reply

  • John Lloyd Scharf

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    I live in an apartment and my neighbors are also armed. If your buckshot comes through my wall, I am going to return fire with my .308 or .45.

    This is home defense – not combat. Since your heart is less than 7 inches, that is enough penetration. This is a video showing what birdshot will do: http://www.youtube.com/watch?v=EA250yz2DR4 Obviously, at 10 feet, it is going to break ribs.

    You are rarely going to have more than 10 feet distance in an apartment. Even a gut shot at 21 feet is disabling, even if it is not lethal. If you think you would not be stopped, feel free to take a round at 21 feet with your heaviest coat to “protect” you. Here is a close shot with birdshot:
    http://www.pathguy.com/sol/07091.jpg

    Reply

  • Firewagon

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    One of my favorite quotes comes from a Jack O’Conner reply to someone asking him about being in the woods deer hunting with a 12 gauge and buckshot. The questioner wanted to know if he would be o.k. with just that 12 ga./00 buckshot combo if he should run up on a bear. Jack replied that with a 12 ga. and buckshot he could walk up to the biggest bear in the woods and spit in his eye.

    Jacks response might have been somewhat embellished, but the point was made. On another note, anyone thinking seven inches of penetration as sufficient should read up on what the FBI thinks about that!

    An aside: double ought (00) buckshot in 12 ga has 9 .33 cal pills in the 2¾” shell and 15 pills coming out of the 3″ mag @1225 fps. #4 buck is much smaller @.24 cal.

    Many pattern their guns @25 yds. That distance would only relate to some palatial estate not reachable with my pocketbook. Most rooms are rarely bigger than 12’x24′ – check out what happens inside that distance with your trusty smoke pole! My ‘night stalker’ is an 870 12ga pump w/18″ cylinder bore barrel loaded with double ought!

    Reply

  • Berserker

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    I seem to recall a gelatin test of a .22 round nose long rifle having better penetration than that. I have the 00 buck in my Mossberg 12ga. That is 15 lead balls at .30 cal and 1200 fps. Now I find out those Remington shells are in a plastic wad cup and come as a package at 7 yards… Nice to know! Not too worried about coming up short in the shotgun department.

    Reply

  • Mike Meserve

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    When I live in a apartment I keep my shotgun loaded with number 4 birdshots. Now I live in a house that is brick as are the other houses nearby. Keep in mind the goal is to stop someone. Most people will stop when shot with bird shot (it hurt). In my EMT text book (many years ago) there was a picture of someone shot with bird shot from the spread on his body is was more then 7 yds away and he was died.
    For now in my home I have the good old stand by load of 00 back up by my 1911 .45acp.
    As alway be safe and shoot stright.

    Reply

  • Azbearhuntr

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    Here we go again! Birdshot is for birds dang it!!! So at 7 yards this specific gun and load combo penetrated what 7 inches or so? That ain’t enough folks!!! There are test results published 50:1 that show birdshot isn’t a good choice. Plus when you limit your self to such a narrow band of effectiveness you are just tempting good ole Murphy’s Law to show up and piss in your cereal

    Reply

  • Lee Helle

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    Guess I’m showing my age but this used to be common knowledge many years ago, of course then we hunted to put food on the table. Darn I must be getting old counting backwards my 1st shotgun was a bolt action 12 gauge sixty seven years ago. (darn gun kicked like a mule)

    Reply

  • olegv

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    Both Remington and Federal make buckshot that uses a cup wad. They produce extremely tight groups and great penetration up close. So birdshot behavior can be duplicated with buck — but not with unbuffered loads lacking a shot cup.

    Reply

  • Bill

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    I own a Winchester 120 pump with sights for slug shooting. I took it to the range as I use it for home defense. I came to the same conclusions as your test, although I just used targets and not jell. For the shorter distance of possible home defense the bird shot was far more effective in a concentrated hit. I of course thought the buck shot would be the winner……..so I bought a case of Royal Buck! You should have posted this article a couple of months ago!

    Reply

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