ckaberna
Gold $$ Contributor
I bought a 6BR rifle from a member on here that was identified as having a .262 neck. Once rifle was received I got to confirming the neck diameter and found that the absolute maximum case neck length was 1.541" well shy of the posted length in my manuals (1.560) , The rifle came with some fired brass that was head stamped "Remington 7BR" so after research, I discovered I had the older "Remington" chamber instead of the the "Norma" chamber. I had already bought a box of Lapua brass that I wanted to use and even after turning the necks and trimming to 1.525 OAL it still didn't want to chamber correctly. After using a "small base die" (cut off .243) I could get them to chamber but below is what I discussed with a reputable and honest smith.....
"If I keep pressures down and MV @ 2750ish all is good. But if I want more, anything above 2790 causes a "sticky" bolt. I have found a "node" at 2851 FPS that has produced a .293, .105 & (2) .6xx groups at 200 yards (all I have shot) and I want to stay there. My question is do I need a complete new barrel in order to use the Lapua brass? Can you or I, "lap" the rear of this chamber to fit the Lapua brass? What sacrifices in accuracy should I expect? Below are some of the measurements I took after dy-chemed the brass to determine the friction point. All measurements are at the ".0200" line above the extraction groove.
New Lapua brass=.4694"
Sized down to = .4673 with trimmed .243 die (cant go anymore due to it's shaving the web)
Low MV fired= .4681 extracts fine
Above 2790 FPS= .4686 Stiff bolt
FYI,
Remington brass sized=.4637
brass fired=.4665"
I eventually removed the barrel and "honed" out the rear of the chamber .002" and no problems since,,,,
Consistently shooting 2850-2860 FPS and no "sticky bolt" and using regular 6BR die instead of small base.
This was ONLY my experience, you may have other issues? Please get a competent person to check out your rifle.
"If I keep pressures down and MV @ 2750ish all is good. But if I want more, anything above 2790 causes a "sticky" bolt. I have found a "node" at 2851 FPS that has produced a .293, .105 & (2) .6xx groups at 200 yards (all I have shot) and I want to stay there. My question is do I need a complete new barrel in order to use the Lapua brass? Can you or I, "lap" the rear of this chamber to fit the Lapua brass? What sacrifices in accuracy should I expect? Below are some of the measurements I took after dy-chemed the brass to determine the friction point. All measurements are at the ".0200" line above the extraction groove.
New Lapua brass=.4694"
Sized down to = .4673 with trimmed .243 die (cant go anymore due to it's shaving the web)
Low MV fired= .4681 extracts fine
Above 2790 FPS= .4686 Stiff bolt
FYI,
Remington brass sized=.4637
brass fired=.4665"
I eventually removed the barrel and "honed" out the rear of the chamber .002" and no problems since,,,,
Consistently shooting 2850-2860 FPS and no "sticky bolt" and using regular 6BR die instead of small base.
This was ONLY my experience, you may have other issues? Please get a competent person to check out your rifle.
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