Hello,
I have turned my Rem 700 LH into a 308/243 switch barrel rig. I rented a finish reamer for the short chambered 243 barrel I was fitting. I established head space with go/no go gauges. Everything seemed fine.
I worked up handloads for the 243. I started .5 grains over minimum load and worked up to .1 over max. None of the test loads showed high pressure signs and the velocities came up as expected according to the chronograph. None of the loaded rounds chambered hard. The thing is though, is that with normal bolt lift, the fired case resisted extraction and shows a scuff on the case about where the chamber ends. I checked for a burr, found none, but did a light de-bur anyway. After doing this, the fired cases still showed signs of sticky extraction.
The only thing I have found helps is shortening my brass length. It seems that the tension is being caused by the neck...specifically the case mouth. Now I typically trim my brass about .010 shorter than the specified trim to length to avoid trimming for the next two reloads. My fired brass did not grow in length from what I had trimmed it to. I took a fired case and roughly ground the case mouth back about .030-.050 on my bench grinder as a quick test. That case now extracts!
Could it be that the reamer I rented is out of spec in the case neck area of the chamber? I intend to set up my trimmer to find out exactly how much shorter my brass would have to be trimmed in order to extract properly.
I have turned my Rem 700 LH into a 308/243 switch barrel rig. I rented a finish reamer for the short chambered 243 barrel I was fitting. I established head space with go/no go gauges. Everything seemed fine.
I worked up handloads for the 243. I started .5 grains over minimum load and worked up to .1 over max. None of the test loads showed high pressure signs and the velocities came up as expected according to the chronograph. None of the loaded rounds chambered hard. The thing is though, is that with normal bolt lift, the fired case resisted extraction and shows a scuff on the case about where the chamber ends. I checked for a burr, found none, but did a light de-bur anyway. After doing this, the fired cases still showed signs of sticky extraction.
The only thing I have found helps is shortening my brass length. It seems that the tension is being caused by the neck...specifically the case mouth. Now I typically trim my brass about .010 shorter than the specified trim to length to avoid trimming for the next two reloads. My fired brass did not grow in length from what I had trimmed it to. I took a fired case and roughly ground the case mouth back about .030-.050 on my bench grinder as a quick test. That case now extracts!
Could it be that the reamer I rented is out of spec in the case neck area of the chamber? I intend to set up my trimmer to find out exactly how much shorter my brass would have to be trimmed in order to extract properly.
