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Charlie Sisk’s Sub-MoA Subsonic .243 Win Load

Charlie Sisks Range, c Nick Leghorn

I was hanging out with Charlie Sisk doing some load development in his private indoor range a few weeks back, and we stumbled across a pretty surprisingly accurate subsonic .243 Winchester load. We were trying to find an acceptably accurate load for one of his friend’s kids to start practicing without much recoil or noise (they have a silencer), and after some trial and error we were getting as good a group as if we’s been shooting supersonic. Here’s the data . . .

Brass: .243 R-P New

Powder: Trail Boss 12.1gr

Primer: Federal 210

Bullet: Nosler 70gr Ballistic Tip

COL: 2.610

Barrel twist: 1:10

As for how well it groups? Check out this 100 yard target:


That’s 10 rounds through the same hole, ignoring the one flier, at 100 yards. We could see daylight through the other side.

Since Charlie was super pumped about this load, I figured it was worth sharing. Good luck, and happy loading!


  1. avatar dave c says:

    That looks like a wicked basement tunnel range!


    1. avatar guy22 says:

      Was it a 100 yard target, shot at a 100 yards?
      Never seen a private basement 100 yard range. How would you build it?
      Great post on the load. Always liked .243 cartridges.

      1. avatar Nick Leghorn says:

        100 yard target at exactly 100 yards. And its actually above ground, in some shipping containers with a big-ass pile of sand at the back.

        1. avatar Joe says:

          That’s what, 10 containers end-to-end?

          I don’t think my wife will let me do that.

        2. avatar EthanB says:

          I had considered doing this with a shipping container for pistol distances. This gives me more “ammunition” with which to convince my wife. That said it will most likely require DHS quantities to do so.

      2. avatar Fed Up says:

        1. You need a big enough culvert to handle the ballistic trajectory of the slowest thing you’ll ever shoot down range.
        2. You need a big enough underground room to set up your bench in, with proper ventilation unless you’re just shooting airguns.
        3. You need a target trolley system to hang your targets from the firing line.
        4. You need a light source at the target end of the tube.

    2. avatar Matt in FL says:

      Please don’t start the “first” stuff.

      Nick, thanks. I haven’t been able to exercise my .243 yet the way I’d like, but this is definitely going on the bookmark list.

  2. avatar Tim says:

    Any idea what type, contour, and length of barrel he’s got in that gun?

    1. avatar Nick Leghorn says:

      Kreiger barrel, heavy profile, 20 inches if I remember right.

  3. avatar Hidden Hills says:

    Gotta love TrailBoss.

    1. avatar Mark says:

      They recommend using non-jacketed bullets with their powder but I suspected that it had uses beyond what they recommend.

    2. avatar Chaz says:

      It’s said that Trail Boss is a fast handgun powder designed for low pressure applications and that it can quickly go over pressure with jacketed bullets e.g. if one is working up a full power load. Loading sub sonic in an otherwise high velocity high pressure rifle cartridge (SAAMI 60k psi) probably keeps everything safe.

      Trail Boss is ‘fluffy’ and can measure erratically. These loads must have had consistent weights. How was the powder measured?

  4. avatar Russ Bixby says:

    Impressive. And shipping containers, eh? Very cool.

    So… was the gun in a clamp, or hand-held? 😉

    1. avatar Nick Leghorn says:

      Hand held, my friend. We don’t cheat 😉

      1. avatar Russ Bixby says:

        Doubly impressive, then. 😉

  5. avatar Russ Bixby says:

    Serious question, though: what about the sides. If I sneezed while shooting my Mosin, a stray might punch right through the side 80 yards on and still be doing a thousand-or-so piles per hour, be reasonably intact and even retain spin.

    With corrugated, the likelihood of a gentle bounce back into the end zone is only about one in three.

    What’s nearby, apart from the sand past the end?

    Just wondering…

    1. avatar Nick Leghorn says:

      On one side there are neighbors, and there’s a berm that runs the full length of the range on that side. But out the back, and the other side, is nothing but state-owned and drilling company owned land as far as the eye can see.

      1. avatar Russ Bixby says:

        Thanks. Just wondering, y’know.

        An infantry rile can pitch ’em a ways, as can most other high power long guns.

  6. avatar Eric says:

    Hey Nick, did you guys happen to chrono these rounds? With a known muzzle velocity (among other things), you should be able to calculate free recoil energy.

    1. avatar Nick Leghorn says:

      One of the previous visitors had shot his chrono, so we didn’t get a firm muzzle velocity. However, based on the powder charge and the sound of the round flying down the shipping container it was definitely subsonic.

      1. avatar Russ Bixby says:

        Shot his chrono? That takes talent.

  7. avatar kb says:

    “We could see daylight through the other side.”

    Daylight inside a private indoor range? Now I am curious!

    Haha, just messin with ya.

  8. avatar lp3056 says:

    Eight shipping containers end to end…only in Texas. ;^)

    1. avatar Russ Bixby says:

      I was imagining six, but that presupposes that at least five are sixty footers.

      That’s one Hell of a visual.

  9. avatar Eric B. says:

    I came into this thread expecting to get some reloading info for my new .243 build. What I came away with was the burning desire to start tracking down some used shipping containers.

  10. avatar Carl says:

    I’m not very familiar with hunting rifle ammunition, but isn’t a .243 reduced to subsonic less powerful than a .38 special

  11. Gday, I tried AS-50 (Australian Shotgun) a ADI powder made in Australia (ADI make Varget), in my .243, using 10.5 grains behind a 75 TNT Speer and got a 75 moa 5 shot group, Speed,, ?? don’t know. Norm, Queensland, Australia.

  12. avatar Howie says:

    Hi. I tried the 12.1grains with 70 grain round and is most defiantly not subsonic IMR list 100 grain only needs 8 of powder. I have settled on 8.7 grains with a short nose 100 grain bullet. Its stable in my Howa 1500 with 1:10 twist. It is a nice round and produces very similar results. It is perfect for foxing in and around livestock.

    70 grain bullet i stopped at 7 grains and it was still supersonic. Wouldn’t recommend going any lower on powder.

  13. avatar Eric E says:

    I have used TB a3 sporter,19gn. Shoots 3/4 ,mow @100. My. 243win w/9.25 twist using 12gns and get 1/2moa @ 100? Both loads I use only standard primers.

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