Is GDP really the best way to look at this though, when the US spends on the order of 2-5x more for equipment and weapons systems per unit compared to the Russian/Chinese equivalents, without necessarily being 2-5x better in real world applications?

It would be interesting to see a more accurate comparison with spending adjusted by total amount and actual purchase/operating costs, though I'm not really sure how to go about doing that, and it gets even more murky looking at price gouging by military contractors for ordinary objects in the US ($50,000 trash cans come to mind.) For the first reason and one above I suspect our actual reported value gained from our budget is vastly overinflated.

I also suppose something similar would be happening in Russia/China, maybe not as price gouging fraud but theft of supplies/funding, which would be harder to compare.

Putin is a war criminal, and let's hope Ukraine inflicts on Russia, a generational defeat. However, you are dealing with a country, that can put 2 millions workers in full war industrial footing.

And whose electronic countermeasures, by the Pentagon own admission, have been recently defeating some extremely sophisticated US weapons.

Don't underestimate an enemy, who can suffer losses unthinkable for Western Armies, with minimal danger of societal collapse....

"Russia's electronic warfare has repeatedly foiled American precision weapons in Ukraine." - https://www.businessinsider.com/russian-electronic-warfare-s...

"Every day, Russia produces 12,320 artillery shells" - https://bulgarianmilitary.com/2024/05/26/every-day-russia-pr...

That's not a particularly high number for a country at war. During WW2 the US averaged around 500,000 artillery shells produced per day. Even in Russia, they are in the early stages of ramping up wartime production, and the west is deliberately hesitant to produce substantially beyond peacetime levels.

"Russia producing three times more artillery shells than US and Europe for Ukraine" - https://edition.cnn.com/2024/03/10/politics/russia-artillery...

They did not go to Korea and China because they can't produce ammunition. They went because they consume so much of it...

"The U.S. Army will boost production of 155mm artillery shells more than sixfold to 85,000 a month" - https://www.defensenews.com/digital-show-dailies/2023/03/28/...

Just for comparison...in the Donbas region, Russia is estimated to have fired 40,000–60,000 152mm shells per day...

That is the US Army current monthly production in two days...

Yeah, Russia is at war, though it is limited. In WW2, for an example of total war, about 1.5 billion shells were used on the western front alone, which is nearly 700,000 per day for 6 years straight. By comparrison 40-60k shells per day is nothing. Russia is ramping up production, they report that their current rate is 2.5X what they were producing a year ago, but it's a drop in the bucket compared to if they were on a wartime economy.

The US, again being at peace, is even less motivated to ramp up its production. While the exact numbers aren't currently known, in 1994 the US had 20.4 million artillery rounds stockpiled. It has sent about 2 million of the oldest ones to Ukraine (equivalent to about 6 months of Russian production), and it is also selling large numbers to Israel. The army wants to boost artillery shell production because they always do, but the fact is the US does not currently need to match Russia's production rate, as it is not using shells at nearly the same rate. It's also worth noting that many other nations are likewise producing artillery shells to send to Ukraine. The limitation on western aide to Ukraine has been political will, not insufficient materiel.