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Rifles, Reloading, Optics, Equipment
Reloading
Video On Bump sizing cases.
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<blockquote data-quote="bigedp51" data-source="post: 1845727" data-attributes="member: 28965"><p>if you place a NO-GO gauge in the chamber this gauge on average is approximately .003 longer than the GO gauge. And on a new rifle, the bolt should not close, meaning anywhere between GO and NO-GO on a new rifle is normal. From there for wear and usage, you have a Field Gauge allowing .007more headspace.</p><p></p><p>The ejector pushes the cartridge forward with no centerline movement and the firing pin hitting the primer can make the case even shorter. Meaning between the ejector and the firing pin the case shoulder is being forced into the shoulder of the chamber. And after firing and brass spring back there should be no excessive effort opening the bolt.</p><p></p><p>And there is no reason for the rear of the case to be pushing on the bolt face. You are not lapping your lugs so why apply pressure to the bolt face. This is why the thumb rule for bumping the shoulder back is .001 to .002 on a bolt action when full length resizing.</p><p></p><p>So how many of you grease your bolt lugs to help prevent galling? And how many of you know why the headspace increases on used rifles, meaning lug wear or lug setback.</p><p></p><p>Below the rifle, I own that allows me to easily change the headspace by changing the bolt head. And I sure do not want excessive force closing the bolt with the possibility of galling the lugs and increasing lug wear.</p><p></p><p> <img src="https://i.imgur.com/v1GFvaK.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p></p><p>Pacific Tool and Gauge offers three lengths of headspace gauges per rifle caliber. In order from the shortest to longest, they are: GO, NO-GO, and FIELD:</p><p></p><p></p><p><strong>GO:</strong> Corresponds to the minimum chamber dimensions. If a rifle closes on a GO gauge, the chamber will accept ammunition that is made to SAAMI's maximum specifications. The GO gauge is essential for checking a newly-reamed chamber in order to ensure a tight, accurate and safe chamber that will accept SAAMI maximum ammo. Although the GO gauge is necessary for a gunsmith or armorer, it usually has fewer applications for the collector or surplus firearms purchaser.</p><p> </p><p><strong>NO-GO:</strong> Corresponds to the maximum headspace Forster recommends for gunsmiths chambering new, bolt action rifles. This is NOT a SAAMI-maximum measurement. If a rifle closes on a NO-GO gauge, it may still be within SAAMI specifications or it may have excessive headspace. To determine if there is excessive headspace, the chamber should then be checked with a FIELD gauge. The NO-GO gauge is a valuable tool for checking a newly-reamed chamber in order to ensure a tight and accurate chamber.</p><p> </p><p><strong>FIELD:</strong> Corresponds to the longest safe headspace. If a rifle closes on a FIELD gauge, its chamber is dangerously close to, or longer than, SAAMI's specified maximum chamber size. If chamber headspace is excessive, the gun should be taken out of service until it has been inspected and repaired by a competent gunsmith. FIELD gauges are slightly shorter than the SAAMI maximum in order to give a small safety margin.</p></blockquote><p></p>
[QUOTE="bigedp51, post: 1845727, member: 28965"] if you place a NO-GO gauge in the chamber this gauge on average is approximately .003 longer than the GO gauge. And on a new rifle, the bolt should not close, meaning anywhere between GO and NO-GO on a new rifle is normal. From there for wear and usage, you have a Field Gauge allowing .007more headspace. The ejector pushes the cartridge forward with no centerline movement and the firing pin hitting the primer can make the case even shorter. Meaning between the ejector and the firing pin the case shoulder is being forced into the shoulder of the chamber. And after firing and brass spring back there should be no excessive effort opening the bolt. And there is no reason for the rear of the case to be pushing on the bolt face. You are not lapping your lugs so why apply pressure to the bolt face. This is why the thumb rule for bumping the shoulder back is .001 to .002 on a bolt action when full length resizing. So how many of you grease your bolt lugs to help prevent galling? And how many of you know why the headspace increases on used rifles, meaning lug wear or lug setback. Below the rifle, I own that allows me to easily change the headspace by changing the bolt head. And I sure do not want excessive force closing the bolt with the possibility of galling the lugs and increasing lug wear. [img]https://i.imgur.com/v1GFvaK.jpg[/img] Pacific Tool and Gauge offers three lengths of headspace gauges per rifle caliber. In order from the shortest to longest, they are: GO, NO-GO, and FIELD: [B]GO:[/B] Corresponds to the minimum chamber dimensions. If a rifle closes on a GO gauge, the chamber will accept ammunition that is made to SAAMI’s maximum specifications. The GO gauge is essential for checking a newly-reamed chamber in order to ensure a tight, accurate and safe chamber that will accept SAAMI maximum ammo. Although the GO gauge is necessary for a gunsmith or armorer, it usually has fewer applications for the collector or surplus firearms purchaser. [B]NO-GO:[/B] Corresponds to the maximum headspace Forster recommends for gunsmiths chambering new, bolt action rifles. This is NOT a SAAMI-maximum measurement. If a rifle closes on a NO-GO gauge, it may still be within SAAMI specifications or it may have excessive headspace. To determine if there is excessive headspace, the chamber should then be checked with a FIELD gauge. The NO-GO gauge is a valuable tool for checking a newly-reamed chamber in order to ensure a tight and accurate chamber. [B]FIELD:[/B] Corresponds to the longest safe headspace. If a rifle closes on a FIELD gauge, its chamber is dangerously close to, or longer than, SAAMI’s specified maximum chamber size. If chamber headspace is excessive, the gun should be taken out of service until it has been inspected and repaired by a competent gunsmith. FIELD gauges are slightly shorter than the SAAMI maximum in order to give a small safety margin. [/QUOTE]
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