Depends on the internals, gearbox, wiring and fire control all relates to how much juice you can feed it.
Some will take it all day, throw a bigger spring in and it will shit itself. It’s all relative. Higher amp draw, higher voltage, if not built for it will fail.
Way back when airsoft was originally built around 8.4V nimh batteries, as things progressed it became 9.6v nimh and then 7.4v lion and lipo batteries. Generally a 7.4v lion or lipo has a much better discharge than a nimh of similar size so runs similar to the 7.4v, but a tad lower in auto.
Short version, by stating anything other than a 7v will void warranty, ensures the blaster has every chance of making it through the warranty and it is your problem when it breaks. And yes, there are ways of telling but it becomes a customers word vs techs word, a battle which a Karen or Kevin will always win and it is still a warranty repair.
That is my experience in the industry. It is usually just a piston or a gear, and usually not that expensive in parts, just someones time.
If a warranty is a value you have, I recommend doing as instructed.
If you are like me, send it, and repair and upgrade myself, I was going to anyway.
Point in case, my custom Pulse rifle.
When that was being built, it was based on a thompson gearbox and shell.
This was designed to run on a 11.1v lipo, so there was no issue running a 11.1v battery, it was designed to do that. (stock, it had the electric blowback feature)
I also upgraded the nylon gears to metal, better piston, oring, m100 spring etc etc.
Net result: even though the nylon gearbox shell was retained, all the other components had been upgraded, for better performance and reliability.
Running 11v was never a problem, all the components could handle it, and the wiring was designed for it.
With the snow wolf PR, it was originally designed for the 8.4v NiMH battery, which has a lower max current output than Lipo. The ROF is much lower than my custom, and even with a 8.4v NimH, it only gets 650 R/min.
I have accepted that is just the way it is, it did run on a 11.1v for a few short bursts, but im not going to risk putting anything above 8.4v in it. It was designed for that battery, not a higher discharge 11.1v Lipo…
Maybe, when it eventually needs a good service, and gets pulled apart, we’ll see what the weakest link is, and upgrade it then…
Do photons count as projectiles? 
Just spotted this at iHobby
Can’t see what brand it is thou.
A “re-release” of the thommies, that xforce had.?
At a lower price point, because they’ve been around for quite a while now.?
Hmmmm…
Mind you, the mags and stampings do look different…
Oh damn… a Thompson. 
Another one to add to the future wish list 
Hanke brand I think from the page.
Don’t think so, didn’t the X-Force ones have real wood furniture and mini Tamiya plug? And doubt they’d sell them this cheap too
Where can you see that? I couldn’t find anything relating to maker.
The xforce one have plastic furniture.
Their brand was not known…it came in the chinglish ww2 box…
Bit of a mystery.
In the airsoft world, there were clones of the TM design.
I suspect it was sourced from those…
X-Force is still selling nylon and plastic Thompsons… same ones?
Big price difference if it is. 
I looked at literally every other line on the site but that one 
. Was even specifically looking for the word “brand”.
just spotted this one.
specs say only 140fps
looks a bit odd in comparison to the Hanke
anyone purchased from this website before?
That Tommy is a super plastic toy version. Almost a CS007 or gelstorm in a big body. The inner barrel ends at the start of the handguard. And unfortunately it contains several travesties on a WW2 replica.
Geltactical, is basically a part of what was M4A1 Gel Blaster. Both their Ipswich and Rockhampton stores, used to be M4A1.
No idea what happened, but Geltactical seems to have much better range than M4A1 at the moment.
