This Gage Spacer fits the 30 caliber PTG Throat Erosion Gage (sold separately) and allows you to measure the throat erosion in your bolt action barrel.
The gauge is used to see the relative change in a chamber's throat by measuring the throat when the rifle is new or when
gauge is first used, then comparing later readings with the first reading taken, noting how many rounds have been fired from
one reading to the next.
The Gauge Spacer is used with the M1-type gauge. The spacer inserts over the M-1 gauge for the corresponding other rifle
listed in the description.
The 224 caliber gauge is used alone in any 22 caliber centerfire rifle where access to the breech is possible.
The end of the gauge (or the spacer) that is inserted into the chamber has a series of lines on it. By noting how far the
gauge can be inserted, one of the lines can be used as an index, or starting, line. Subsequent uses of the gauge and the
corresponding line that can be seen when the gauge is inserted will give a difference in dimension between the two lines. If
this difference is then measured (with a dial caliper or other measuring device), the result is the amount of throat erosion that
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