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Out of all the rifles I've bedded with 10110, I doubt I've ever had the same mix ratio. I measure with a couple tablespoons, and eyeball it. But then, I've mixed alot of Bondo in my day. They've all turned out perfect.

I guess the weighing it on a scale is a good idea… ::)

Well…it depends on how much you believe in “measurable  results”. ;D
I have used epoxies for 20+ years – in industrial application/critical situations ( fixing bridges, dams and elevated parking decks and even some “hot side” nuclear power plant work) in which batch retains were kept and tested for the resultant strengths. Really measured strength…not “well it seemed to get hard enough for me”…. ( that's what she said… ;D) Inadequate mixing – or “Off-ratio” mixed materials can create “creep”. Creep occurs when you have dynamic loads that in this case – are much like the physics that result at the action/stock/recoil lug interfaces when you you squeeze the trigger, and a round causes recoil. “Creep” is materials that seem to have hardened – but managed to get pushed, or squeezed out from their original placement once cured at the time of installation. It is something that would me measured in thousandths  – but in some applications for epoxies ( as mentioned above in my old line of work) shows that we get less than the best performance when we have “creep”. Creep allows some movement in the structures where we were trying to stop said movement.
And – if the mix ratios were off by more than 3% – the test results would show that the compressive, tensile elongation, and tensile numbers were not up to the manufacturer's specs. A good predictor of creep…Since you cannot remove what has been mixed and injected under thousands of pounds of pressure – you MUST get it right in that situation.
So – I am not comparing bedding a rifle to my old vocation – in fact, this will be my first attempt to bed a rifle. But, you can bet your butt-pad that I will mix it correctly. By  weight if that is what the manufacturer says. By volume if that is o.k. with them – but thoroughly none the less.

If you have a friend that is a dentist – ask him for some of the tools that he will discard – after sterilizes and inspects them. The picks are great for bubble puncture, and they actually use some small spatula like tools sometimes for mixing dental grade acrylic adhesives.
Just have plenty of tools on hand, and use what feels best for you to remove-mixed materials from the main mixing  tool,and get it re-incorporated into h batch of material. That will help you stay “on target” with your mix ratio accuracy.

You can get a decent digital scale from any store nowadays. They are cheap and popular due to our need for dieting. Less than $20 bucks – and often, $10.
I like clear mixing cups, so I can tell where there is any virgin material remaining. As well, I get some cheap,small, stiff rubber blade spatulas from the kitchen store. And – I get tongue depressors – and cut one end of them off – so that is is “square” to the bottom of the mixing cup. This allows you to get into the corners of the cup.
Folding material in toward the center from the outer edges – without entraining air is key with many of they heavy viscosity epoxies.

Hope this helps….I will have questions about exactly WHERE to bed the stuff in my stock. I may know how to mix it – but, this specific placement of epoxy is a first for me.