Need to crimp bullets?
To give some closure, I took the rifle to a smith. He claimed that he didn't work on it because it failed a headspace test. Despite that claim, the rifle feeds from the magazine now.
09-02-2012 12:58 AM
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So that's yet another headspace gauge crushed by an M1917? No, that was not a joke. The final closure of the M1917 bolt has (if I remember correctly) a 1% camming angle. So if the smith left the firing pin and spring in the bolt while testing, he had to apply a few pounds of pressure on the bolt handle to close the bolt. Pounds of force on the bolt handle translate into hundredweights of force on the bolt face.
Originally Posted by CouldBeWorse
To use a headpace gauge correctly, you have to remove the firing spring, bolt and extractor, and let the bolt handle just about fall under its own weight. If it stops before reaching 100% closure, because the bolt face is touching the gauge, then all is OK. Pushing the bolt handle down with your thumb will put an enormous force on the gauge, and the test is invalid.
Need to crimp bullets?
I've heard about both "stretched receivers" and "crushed gauges". I'm curious which is more likely, as I have a field gauge, but got it from a friend, so it has an unknown history.
`Tis a bone of great contention, so tread warily if Enfield fans are in the vicinity, but a Lee-Enfield action, with rear-locking lugs, will be stretched a wee bit on firing - within the elastic range of the metal. So it returns to the initial dimensions after firing. Mauser-type actions (of which the M1917 is one) have front-locking lugs. The firing cannot strech the receiver portion behind the lugs.
What can happen, in all types of action, is that a very heavy overload (on the verge of destruction!) can stretch the receiver and barrel rings beyond the elastic limit. Or set back the bolt lugs. An action in this condition is something I would stay away from. Crushed gauges are probably much more common than people think - how many gauge users have their gauges regularly recalibrated? Very few, I suspect.
But a gauge that has been crushed is WORSE than useless, because it leads to a false verdict on all the rifles in which it is subsequently used! Gauges require the touch of a watchmaker, not a heavy hand on the bolt handle!
Last edited by Patrick Chadwick; 09-02-2012 at 06:09 PM.
Really Senior Member
Given how hard gauges are, crushing one may require a bit more force than even the helical locking of an M-17 action could apply.
The bigger danger is that the very hard gauge will be simply ploughed into the somewhat softer (but definitely not "butter-like") steel in the receiver, barrel and bolt. The ramming leverage in a P-14 is substantial.
My training was to ALWAYS close the bolt / breech block (as applicable) with GENTLE finger pressure when using GO/No-GO gauges in ANY firearm, be it "military" or not. Gauges that have fully-formed rims or extractor grooves are a particular concern. Drop the bolt of a semi or auto toy on such a gauge and you may not only damage the barrel, but you will may also damage the extractor and the gauge itself.
The hardened steel doesn't distort easily. It can, however, fracture. I have seen gauges that have been dropped "rim down" on concrete floors lose chunks off the "rim". Most military gauges these days seem to have the rear of the gauge rebated to completely clear the extractor AND, very importantly, any spring-loaded ejector plungers that may be present in the bolt face.
Most gauges for rimmed cases, like .303 and 7.62 x 53, are short stubs with rims. You don't need a gauge with a shoulder ast the headspacing is actually HEAD-spacing. They will still break if you abuse them.