Ok so as we all know, blasters work well for modding, and certain ones suck! Some will get you above 100' flat modded, some are impossible. So let me give you some criteria of what to look for.
My pistols disprove the myth that a small Plunger Tube area will never get you sufficient power, but only to some extent. Anything below 20cc's (like Ix-3 scout for example) will never be able to work in past elite velocities. But a Firestrike with enough yield, pretty good speed but not 200 fps range. Volume wise, anything past 28cc's can get you above 140 fps no problem, if your willing to extensively mod it, ....and if that's your cup of tea.
They lack that direct transfer of energy that a straight plunger system has. Also, past a certain yield of spring, the are impossible to 1 hand prime. The PT's are also small so the most you will get out of one continuously is probably 75-80 flat, which is not bad, but it's not great either. This is largely why most of my modded pistols are draw handle pistols.
Low inertia pistons:
Pretty good bonus, but not everything, for example a Magnus can't prime past 10kg's for the reason that the trigger catch can't hold it. However, I have gotten a Sharpfire to hold 25Kg's because of it's better plastics it uses and the fact the trigger catch is wider, but 21kg's is most effective at it volume of 34cc's.
Bane to a good sealed breech pistol, absolute poison. Not the end of the world but it basically says to me when I see it "forget this one being a 150' flat blaster." Even the Cyclone Shock, I have never seen one do better than 130 fps. Revolver mechanisms in nerf blasters also aren't accurate enough to take advantage of long range either.
Soft plunger rods and weak trigger catches:
Like the Firestrike that can only take 16Kg's reliably, but 16 may be all you need. The Rebelle blasters like the Pink Crush and Star Shot are made with a higher density soft plastic, as a matter of fast the Bird Of Preys use this. Not the end of the world, people make replacement plunger rods (like Ve Nom) and one can make one out of Delrin or HDPE with some machine tools.
The Pink Crush is awesome for example, but you need to use a 7kg OMW Strongarm spring and a black tactical V1 because it has less spring clearance. Personally the freedom to use a full 8Kg swarmfire spring and a Black Tactical V2 spring makes all the difference in the world if sticking to a stock PT on a Firestrike which has a fill inch of spring clearance in full prime. Others much more limiting, like the Strongarm with only 1/2 inch of solid spring clearance.
Too little spring clearance prevents a modder from being able to use heavy gauge springs (1.7mm and above), hence less potential for power.
Slam mode hates spring upgrades and can't take serious yields easily because it's one more thing that can go wrong trying to make it work.
One problem you may see is the phenomenon called "auto-slamming" that happens when you prime a blaster like the EAT forward too fast and it fires even when the trigger is not pulled. Xplorer, for example bastes their kits on Longshots and Retaliators with no slam mode for a good reason and a decent shooter should be able to pull the trigger just fine every time the breech is moved forward in rapid sucession without any issues, just takes practice.
Refers to an unmodded nerf breech, and at some point if you wanna climb past 10 Kg yields, you just need to buck up to some brass or sealed breech kits.