I've seen a couple on line with a small ball bearing . Do theu provide any significant reduction in torque and is there any disadvantage to using one.
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I've seen a couple on line with a small ball bearing . Do theu provide any significant reduction in torque and is there any disadvantage to using one.
YES, good ones work as advertised.
and NO, there is no disadvantage or negative side effects to using them.
First thing I did to both my new 12FV's was to put in the 38cal bolt lift mod.
A big improvement!
I've seen these but don't understand how they work. Are they bard to install?
One must attempt to maintain similar spring compression in the cocked position as prior to the modification.
Very simple installation. Grab a 38 cal brass and cut off everything above about 3/8 inch of the head ( I use a tubing cutter). De-burr. Have a ball bearing handy that'll fit into the primer pocket. It needs only to extend just above the face of the brass case while sitting snugly into the primer pocket. You'll also need a washer under the BAS (bolt assembly screw) to do as Robinhood warns. I find that a standard 1/2" aircraft grade washer (1/16" thick) fits perfectly. Grease it up and install.
Why they work: As designed and manufactured, the cocking sleeve rotates against the BAS while cocking and under pressure from the firing pin spring. That's a lot of surface friction acting against a surface that is not precision ground for smoothness or flatness. The 38 cal mod reduces that friction area to the tip of a ball bearing.