6.5x55 Headspace Gauges

Many owners of Swedish Mausers have dropped in American headspace gauges and been disappointed that it closed on a no-go gauge,
erroneously thinking their rifle had excessive headspace. This isn't true. The simple fact is that Swedish Mausers were not chambered
to American S.A.A.M.I. specifications. To top that off, there were at least two standards used in the years the Swedish Mausers were in
use (until the mid-1980's). My information comes from 1948 ordnance orders specifying what the standard would be from then on.
The following brief statements are direct translations from those 1948 ordnance orders.

The following is a comparison between Swedish regimental headspace gauges and
commercial American gauges. For an overview on the meaning and significance of headspace measurements see Cruffler.com.

This is a set of Swedish regimental headspace gauges. The first number is the headspace length, the second number is the distance from the barrel breech
to the bolt face.

The sizes are:
46.50mm, 3.15mm
46.55mm, 3.20mm
46.70mm, 3.35mm
46.80mm, 3.45mm

This is a set of Forster commercial gauges:
go =      1.7794"
no-go = 1.785"
field =    1.789"

For comparative purposes only, the gauges were inserted into the breech of a new m/96 barrel and the projection measured with a dial caliper. This method proved to be accurate to under .002".

Measured projections:
  • Go =      .119"    3.15mm = .123"
  • No-go = .124"    3.20mm = .125"
  • Field =   .129"    3.35mm = .1335"
  •                           3.45mm = .135"

      What this means is that Swedish chambers are longer than American gauges can accurately gauge. Your rifle can fail the
      no-go test and be perfectly fine... by Swedish standards. I've heard many stories of rifles being handed over to gunsmiths
      to have the headspace re-qualified when there's nothing wrong with them. For those who do not handload there's little need
      to do anything other than shoot and enjoy. In 36 (now 42) years of shooting and handloading the 6.5x55 I've not had a single
      problem with case life beyond normal and you probably won't either.

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