M77 or M77 MkII?
* The original Ruger M77 (often called "tang safety") uses a sear block safety that also incorporates a lever that locks the bolt.
* Newer Ruger M77 Mk II rifles use a trigger block safety that incorporates a plunger that locks the bolt.
Which is best?
* Sear safeties are supposed to keep the sear from falling even if the trigger is pulled. The advantage is that the sear itself is held in place, which will keep the firing pin from releasing. Problems with this type of safety is that very small amounts of wear can allow the sear to fall off of the nose of the trigger sear and discharge when the safety is pushed off.
* Trigger block safeties keep the trigger from moving when the safety is engaged. Advantages of this type of safety are that the sear cannot fall unless the trigger moves, which requires releasing the safety. Disadvantages of this are as above, very small amounts of wear can allow the sear to fall off the nose of the sear if the trigger is pulled when the safety is engaged, which will allow the rifle to discharge when the safety is pushed off.
Most safeties we see are trigger block safeties, but there are some rifles on the market that incorporate both types into the same trigger. And some manufacturers (Winchester is famous for theirs) simply do away with the trigger safety and use a firing pin block.
