8x57 & 7x57 head space gauge needed for use

akrifle

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Any of you guys in Anch area have 7x57 and or 8x57 head space GO/NO-GO gauges to help me out? I'll drive to whever if you could check the rifles before I shoot them.
 

gunbugs

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If you can make Fairbanks stop by. It'll just take a couple minutes each.
 

akrifle

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Thanks gunbugs, I know it just takes a second, but I can't come to FB. Still looking in Anchorage.
 

bandhmo

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I do not have gauges but the poor mans method has always worked well for me. All you need is a new factory load and some scotch tape, and some calipers.


  1. Take a new unfired factory load and measure the cartridge overall length.
  2. Remove the firing pin assembly from the bolt for safety, and so the cocking piece does not reduce teh feel of the bolt closing. In a a rifle with a spring loaded plunger type ejector it may be best to also remove the ejector. In mauser I leave the extractor on or else the band can expand into the safety lug recess.
  3. Chamber the round and make sure it chambers with out force. If so I consider it to have passed a go test, at least for use with that ammo.
  4. Remove the cartridge and place a single layer of scotch tape over the head of the cartridge. With a sharp knife trim off the edges. Measure the cartridge over all length. The difference is the increase in head space for this modified round. Generally scotch tape is 0.0015 to 0.002" thick.
  5. Load the modified round and note the force to close the bolt.
  6. Repeat steps 4 and 5 adding layers of tape. Till it takes noticeable force to close the bolt.

If it takes less then 4 layers of tape (about 0.008") to make the bolt firm when closing I consider the rifle to be in spec, or well with in safe to fire. If taking more then 0.012" of tape I would consider the rifle to be questionable and want to get some real gauges, Keep in mind that factory rounds are sized to somewhat under go length. If between less then 0.012" of tape are needed I would still consider it safe to fire but any hand loads would be made with the die not screwed down all the way.

SAAMI spec varies but in general a go gauge is defined to chamber minimum length. A Field gauge is 0.012" longer, and rifles chambering a field gages are considered unsafe. There is no spec for go gauges and they are often made 0.004" to 0.006" longer than a go gage, depending on manufacture. A case head spearation is unlikely with new brass provided head space is even close. And if reloading the dies can be setup high so as to make excessive headspace a non issue.
 

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