While not the equal of a JB welded erector tube, here are some modifications that make the Leupold BR36 perform reliably. The back of the erector tube is held against a beveled shoulder in the scope tube with a wave washer. If the wave washer fails to keep the erector tube seated firmly, it can shift from side to side. I have made a small sleeve with a stepped bore that fits over the back of the erector tube. This sleeve has a spherical outer diameter that fits into the smooth section inside the back of the scope tube. The clearance is set to around three ten thousanths, and has grease to even further tighten the clearance. The erector tube is allowed to pivot freely with no off center movement.
I measured the wave washer at .053" thick uncompressed and .025" compressed. With depth mics, I was able to determine that the spring was only preloaded to .040". I made a shim washer to compress it down to .030" for maximum seating force of the erector tube. With the retical cage seated against its shoulder, this leaves only .005" before fully compressed. If the erector tube moves back now, it should only have an effect on focus since it can't move any other direction.
I have also added a posi-lock system. When making this modification the tiny boss that holds the spring in place is machined away. By turning the tip of the posi-lock screw down to a diameter that fits into the hole of the spring, the original flat spring is still used to make the scope track during adjustments before the posi-lock is tightened down.
Back of erector tube showing beveled shoulder
Thin erector tube sleeve showing stepped bore
Modified tube with sleeve installed
Wave washer and extra preload shim
Notice shoulder on reticle cage, this determines wave washer preload. FRAGILE!!!
Notice boss on tension screw for locating flat spring.
Posi-lock finger knob
Leupold style posi-lock cover
Michael
I measured the wave washer at .053" thick uncompressed and .025" compressed. With depth mics, I was able to determine that the spring was only preloaded to .040". I made a shim washer to compress it down to .030" for maximum seating force of the erector tube. With the retical cage seated against its shoulder, this leaves only .005" before fully compressed. If the erector tube moves back now, it should only have an effect on focus since it can't move any other direction.
I have also added a posi-lock system. When making this modification the tiny boss that holds the spring in place is machined away. By turning the tip of the posi-lock screw down to a diameter that fits into the hole of the spring, the original flat spring is still used to make the scope track during adjustments before the posi-lock is tightened down.
Back of erector tube showing beveled shoulder
Thin erector tube sleeve showing stepped bore
Modified tube with sleeve installed
Wave washer and extra preload shim
Notice shoulder on reticle cage, this determines wave washer preload. FRAGILE!!!
Notice boss on tension screw for locating flat spring.
Posi-lock finger knob
Leupold style posi-lock cover
Michael
Last edited: