09-29-2021, 05:11 AM
(This post was last modified: 09-29-2021, 05:14 AM by r.tenorio671.)
Quote: "I just got back today from the range, and I tested out some loads that I thought weren't belting when I worked them up. They belted with the AGB closed to 1 click past LRBHO."
...by having your AGB set to "1 click past LRBHO" you are defeating the purpose of the test to determine if you are getting an early unlock of your bolt due to overpressure from a hot charge weight. If the gas is turned off completely to prevent the BCG from cycling then the bolt will not attempt to unlock. An early unlock can occur with overpressure rounds causing the casing to start extracting while pressure is still high enough that the resulting unsupported portion of the casing web "over expands" due excess pressure still present. Typically, the resulting bulge will primarily be on one side of the casing, but could also be completely around the full circumference of the casing. One thing that wasn't mentioned is what dies are you using? In the last picture posted those lines delineating the "band" on the web are typical when using small based sizing dies that squeeze the casing down to minimum SAAMI spec (commonly used for ammo to be used in semi-autos to ensure chambering success across differing brands of barrels). Your load of 26.5 of Varget is almost at Hornady's max of 26.7 and over Hodgdon's 25.8C (compressed for 107SMK) for Varget. The symptoms you have related are common to an overcharged load, i.e., case web expansion, cycling issues, buffer/gas block adjustments, etc. These are why it's recommended to use the standard buffer & buffer spring initially to get baseline data before making changes to anything.
...by having your AGB set to "1 click past LRBHO" you are defeating the purpose of the test to determine if you are getting an early unlock of your bolt due to overpressure from a hot charge weight. If the gas is turned off completely to prevent the BCG from cycling then the bolt will not attempt to unlock. An early unlock can occur with overpressure rounds causing the casing to start extracting while pressure is still high enough that the resulting unsupported portion of the casing web "over expands" due excess pressure still present. Typically, the resulting bulge will primarily be on one side of the casing, but could also be completely around the full circumference of the casing. One thing that wasn't mentioned is what dies are you using? In the last picture posted those lines delineating the "band" on the web are typical when using small based sizing dies that squeeze the casing down to minimum SAAMI spec (commonly used for ammo to be used in semi-autos to ensure chambering success across differing brands of barrels). Your load of 26.5 of Varget is almost at Hornady's max of 26.7 and over Hodgdon's 25.8C (compressed for 107SMK) for Varget. The symptoms you have related are common to an overcharged load, i.e., case web expansion, cycling issues, buffer/gas block adjustments, etc. These are why it's recommended to use the standard buffer & buffer spring initially to get baseline data before making changes to anything.