Use the Right Ammo (and Answer Questions from Newbies)

A few years ago I found myself embroiled in an ammo debate – okay, an argument – with someone about .40 S&W versus 10mm. No, this was not a discussion involving name-calling of the .40 S&W or a talk about wound cavities, recoil, or, well, anything. It actually had to do with the cartridges themselves and the dimensions of the barrels of guns chambered in them. I finally abandoned the argument, but I’ve never forgotten. You guys have undoubtedly had numerous “discussions” about ammo and its interchangeability – or lack thereof – over the years, with varying degrees of success.

Confusion over the differences between cartridges varies between the understandable to the frustrating. Just last week a newcomer to a gun-related group on Facebook asked a question about 7.62 ammo – just 7.62 ammo, with no mention of which one he was referring to. A few days ago someone else was confused about .30 caliber bullets, not understanding the differences in the many, many .30 cals on the market. Then there’s 5.56 versus .223, standard versus +P – there’s a lot of information out there.

Apparently hickok45 has received his share of questions regarding about ammo because he recently posted a video covering the importance of using the right ammo in the right gun. After all, just because a round fits in a gun – sort of – doesn’t mean it should actually be fired in that gun. It may seem basic to experienced gun owners but remember that we all had to start somewhere and certain details are harder to grasp than others. If it seems like an odd or overly simple posting for TFB, keep in mind that newbies hit the site on a daily basis looking for answers to questions. It never hurts to touch on basics now and then. So take a look at the video. Who knows, you might learn something.

So what spurred this? Think of it as a sort of a PSA. When someone who does not know as much about guns as you do starts asking questions, try to be patient. Far too many potential shooters are scared off or discouraged by snarky responses from seasoned gun owners – or gun owners who just think they’re seasoned. Always be willing to answer legitimate questions. Heaven knows the industry can always use dedicated gun owners.

TFB Staffer

TFB Staff, bringing you the latest gun news from around the world for a decade.


  • iksnilol

    In Europe all 5.56/223 barrels are proofed at the 5.56 pressures, so that issue is non-existent.

    308 can be shot in a 3006 Mauser (controled feeding holding the round at all times in the cycle). Not recommended but can be done. I’ve seen it done. Produces weird almost straight walled 308 cases.

    • ostiariusalpha

      It’s not necessarily that the barrel will fail with one or two (or thirty) shots, but shooting 5.56 in a barrel chambered with a .223 leade will ruin the precision of any shot, damage the brass, and (in a self loader) cause very rough cycling. Habitually shooting the wrong round can and will do damage to the smaller lugs of autoloading guns and to the chamber even on manually loading rifles. It’s always a bad idea unless you have a chambering (like .223 Wylde) that won’t produce pressure spikes.

      • iksnilol

        I really doubt it will damage the brass or cause violent cycling.

        • ostiariusalpha

          Pressure spikes ALWAYS cause such things. I’ve damaged brass even on guns with the correct chambering from shooting slightly hot loads on too warm days.

    • Al Brautigam

      Standard 5.56 pressure levels aren’t the problem. There really isn’t much difference anyway. They’re measured with different methods. When measured by the same methods, there is little difference in pressure.

      The problem is with the different leade depths. A 5.56 in a .223 chamber will create a dangerous pressure spike well beyond the proof pressures of either round.

  • BattleshipGrey

    In school math wasn’t a big priority for me, other than to not fail. But when I got into guns, math and measurements jumped up the list. I’m still no Einstein, but I’ve become much more astute because of my gun hobby in multiple ways.

    Sometimes it’s hard not to give people the long answer to a question when you’re very knowledgeable about a subject, but I try my best to give them the simplest answer in the safest way. My dad is an electrician, but whenever I’d ask an electrical question growing up, I’d get the long answer, and to this day I have very little knowledge in electrical issues because it all went over my head.

    • Jwedel1231

      Short answer to every question about electricity: Black magic.

      • bull

        Wrong! magic smoke! dont let it out! 😛

    • charlesrhamilton

      Quote from an old Cowboy: “There’s only two things in this world that scare me; fat girls and electricity.”

  • gunsandrockets

    And as if things weren’t confusing enough for the newbie shooter, Sharps invents new confusion with the 25-45 Sharps cartridge!

    What could be better than mixing english and metric measurements, in a format that was used for designating 19th century black powder cartridges?

    • ostiariusalpha

      Or year of adoption for early 20th century cartridges.

    • Anomanom

      Oh lord they actually did that. I thought you were joking. /headdesk

  • TechnoTriticale

    Another problem with this topic is that the SAAMI document on unsafe combinations is seriously incomplete.

    One could argue that .38 Super in 9mm largo is too obscure to mention.

    But 300BLK in 5.56×45 is not (and oddly, they do mention 300BLK under .223 REM).

  • Hudson

    I have a Martini Cadet Rifle that has been re-chambered in .32 Winchester Special, it’s mind boggling how many different types of cartridges I could chamber and fire, just about anything related to the 30-30 case. .219 zipper, 25-35, 30-30, etc. etc.

    • TechnoTriticale

      re: .32 Winchester Special, it’s mind boggling how many different types of cartridges I could chamber and fire…

      Harmlessly, but inaccurately, for most of them. The focus of this TFB article is on UNSAFE combinations, something that is inadequately documented.

  • rrdonovan

    Dear Nubie

    Just use the round designed for your weapon. No thinking required. That was simple enough. Everyone reads too much into this.

    • TechnoTriticale

      re: Just use the round designed for your weapon. No thinking required.

      For many newbies, their first firearms are used, often old, possibly even in chamberings for which ammunition is no longer offered. What is stamped on the barrel may be of no help, or even misleading.

      I once owned a Llama in “9mm Largo”. I had to write to the NRA to find out what was safe to use in it (.38 ACP, but not .38 Super). SAAMI still won’t tell you.

      I once owned an 8mm Lebel, for which, at the time, ammo was still available. I’ll bet lots of things might chamber and kaboom in that, but SAAMI won’t tell you.

      I once owned a Winchester’94 in “.30 WCF”. You don’t today find ammo so marked (everyone else has called it .30-30 for many decades). SAMMI won’t tell you anything about unsafe combos for either .30 WCF or .30-30.

      Colt DAs are popular with retro shooters. They are simply marked “.38”, but are “.38 Long Colt”. These .38 DAs will chamber and fire the full range of .38 SPL, right up through .357 Mag. Light .38 SPL wadcutters will be merely inaccurate. Anything stronger is a kaboom risk; a certainty for .357. SAAMI’s chart is also completely silent on .38 LC.

      TFB might consider doing a public service by publishing and maintaining a more comprehensive chart.

      • Bill

        and .38 S&W vs .38 Special.

  • Shmoe

    I am curious as to the details of the .40 Smith vs. 10mm debate. I’ve been witness to such a debate; not to mention, it’s empirical resolution.

    FYI, a Glock 20 (a 10mm Auto) will feed and fire 40 S&W just fine. 🙂

  • Southpaw89

    I find it encouraging that so many are asking questions like this, first off it likely means an expanding interest in the shooting sports, and secondly it means that people are willing to ask and are taking their safety seriously, meaning less accidents to be touted by someone claiming guns are too dangerous to own.

  • Dwaine Dibbly

    A little knowledge is dangerous! For example, I can see somebody coming up with this logic and resulting BAD ideas:

    1. S&W Governor chambers 45 ACP (with moon clips), 45LC, and .410 shotgun
    2. S&W 460 Mag changers 45LC, 454 Casull and 460 Mag.
    3. Therefore, I can fire 460 Mag & 454 Casull in my Governor and I can hand-make shorter .410 shells for the 460, right?

    (Actually, it would be great if the 460 X-frame was machined for 45ACP moon clips.)

  • Jim_Macklin

    Years ago I picked up a, as I recall, 30 Russian unfired cartridge, from the gravel at a public KDWP range. The case was mangled. I think somebody asked a Walmart sales associate for some 30 caliber ammo. It did not fit in a .30/30 chamber. [Maybe it was other way around, I can’t find that case now.]
    I’ve often wondered about loading a 5.56×45 round into a .375 H&H. [not recommended]

    • iksnilol

      You’d det double power. A firearms and ballistics scientist known as Mattv2099 (also known as the inventor of the 600 round Glockazine) tested this. He made a triple round (a .22 in a .410 in a 12 gauge). The results were devastating. It was 200% more bullet per bullet after all.