Are they dovetail or weaver mounts?
What would be the best pellets for this rifle?
I can find no detailed information about the RS3 trigger and what it can be adjusted to weight wise at both extremes? How clean does it break ect.
can this gun be decocked, if so how?
No. Once it's cocked, you have to shoot it. Please don't dry fire it either.
The only way to do it would be to hold the barrel, take the gun off safe and pull the trigger. You would have to control the barrel as it goes up. I would not recommend doing this though. It's much better to simply load a pellet into the gun and shoot it into the ground if you need to fire it off.
Which Alloy NON LEAD Pellet is a good choice for the Beeman Mach 12.5
I would go with the H&N brand in both .177 and .22 caliber
Is the stated fps for lead pellets?
I got 1006 fps (28.43 fpe) Avg. 999.4 fps using Beeman Silver Bear .22 Cal 12.65 Gr. pellets. So I would say that it is for lead pellets. Not all lead pellets though. Got 892 fps using 17.13 gr Silver arrow pellets that's 30.34 fpe!
The stated fps is for lightweight alloy pellets.
looking for a scope to stand up to the recoil. for about hundred twenty dollars or less
I would suggest a Leapers 3-9 power scope. They are durable and seem to be the best overall in that price range.
Is this air rifle built to last? Is the cocking rough?
It is not a German made Beeman, it's made in China and the cocking effort is a stiff 60lbs
How is this different than the Rs1/Rs2?
The Mach 12.5 has a different power plant and generates more velocity due to the different spring piston configuration.