Field Expedient Barrels

Tubing sizes for improvised firearm barrels from .22 Rimfire to 12 gauge shotgun.
Seamless Mechanical Tube (SMT)/Seamless Hydraulic Tube (SHT)

Calibre Tube size required (mm) Bore dia. (mm)
.22 Rimfire 9.53 x 2.03 SMT 5.47
9.52 x 2.03 SHT 5.46
.25 ACP   12.70 x  3.25 SMT 6.20
.32 ACP   14.29 x 3.25 SMT 7.79
.38/.357 15.88 x 3.25 SMT/SHT 9.38
  19.05 x 4.88 SMT 9.29
 9mm/.380   14.29 x 2.64 SMT 9.01
  14.00 x 2.50 SHT 9.00
  15.00 x 3.00 SHT 9.00
.44/.410   20.64 x 4.88 SMT  10.88
  19.05 x 4.06 SMT  10.93
 .45 ACP   17.46 x 2.95 SHT  11.56
 12 Gauge   26.99 x 4.06 SMT  18.87
  28.58 x 4.06 SMT  20.46
  28.00 x 4.00 SHT 20.00
30.00 x 5.00 SHT 20.00

Got to love these sort of ‘information only’ sites haven’t you?

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5 Responses to Field Expedient Barrels

  1. equippedcat says:

    Of course, accuracy of information would be nice.

    The bore of .22LR is .556
    The bore of .38/.357 is .907
    .44 and .410 are not compatible. .410 and 45LC seem to be
    The bore of 12ga is 18.52

    Although, for a field expedient barrel, it is not the “bore” (diameter of the bullet) which matters as much as the “chamber” (diameter of the case). Rifle and pistol cases are usually not that thick, but shotgun cases are somewhat thicker which is how a .410 shell can safely fired in a lengthened .45 chamber.

    And what is with the rimless cases being included? If you put a rimless case into a tube which will accept it, what keeps it from just moving down the tube? Of course, it you get a tube with the right BORE and have a chambering tool, then that could work, but would that be considered “field expedient”?

    • What is a barrel? It’s a pipe.
      Both Holmes and thehomegunsmith use (d) the same tabling for sizing ‘pipe to calibre’ and the HomeGS includes roll your own info for those are really less fortunate and live in totally gun ignorant cultures.

      To me provided a round leaves the barrel, and I’m left standing to tell the tale, the dimensions work.

      Does it make for long range accuracy? Nope. Garden range accuracy at best, phone booth accuracy for the rest.

      As for chambering?
      The breech I saw being made (a pipe fitting) was ‘chamber sized’ with an old spent casing full of hard solder hammered into that ‘breech’. Sensible I thought as was dropping a pulled bullet down the pipe to check one would actually fit and clamping the weapon to fire the first mag off with a bit of string tied to the trigger.

      Beggers can’t be choosers my friend.

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