I'm in the process of building a lightweight rifle based on a Remington 700 action. From what I understand, I can drop 2 oz with a speed lock firing pin assembly which I can install at home myself.

For those of you that have done this, have you been happy with it? Any issues with pierced primers or dry fires?

Don't know about 2 oz drop unless you are going with the aluminium shroud but you won't pierce primers if the protrusion in correct

Put together a couple light faux Ti Remingtons myself

The savings in weight is in the stock/pad, aluminium shroud, aluminium trigger gaurd, blind magazine and a thin barrel

Yes, the assembly includes the aluminum shroud as well. Do you know how much the weight difference is between the factory shroud and the aluminum alternatives? The weight is the real thing I'm after, not the lock up time. If the shroud itself is where all the weight is, I can swap that vs the whole shroud/pin/spring assembly.

Rifle still has the factory barrel on for the time being (270 caliber). Stock is a Manners EH6 with the blind magazine box and a 1/2" pad. The trigger guard is aluminum from PTG. Rings are the Talley Light Weights and I'm debating heavily between the popular 2.5-8x36 Leupold at 11.4 oz vs a 2-7x33 Leupold at about 9.9 oz for the scope.

About 2 ounces on the shroud

Most recoil pads are heavy.....a pair a summertime flip flops make the best ultralight recoil pad

I fluted my bolt body and handle and even fluted the mag box

When I was finished my Kimber Montana was still lighter by nearly a pound

Part of me is still debating selling the whole rig and getting the kimber. Still would need a new recoi pad though. I'm 6'2" so "average" is still too short lop for me.

Kind of enjoying the 700 though. Had lots of hate before, but so far like the action.

The aluminum shank Speed Lock firing pin is not your best option...as it will break at the most opportune time.

I have used the D. Tubb fireing pin and firing pin spring in most of my M700 and my Ruger 77. Not to save weight but to decrease Lock Time. I would look at other ways to loose weight. Stock, recoil pad, barrel lenght and profile.

General rule when assembling a light weight rifle is that if you pay attention to the ounces, the pounds will take care of themselves.
Hollow out the bolt knob, holes in the handle, slots in the receiver, no open sights, alloy rings and bases etc. all add up. Depending on caliber removing 2" of barrel will decrease weight by as much or more depending on diameter. All things to consider.