There weren't any bulletproof fighters in WWII.
I made the Bf 109 flimsy remark in comparison to the P-47. Or do you want to make a statement that the survivability in a Gustav was the same as a Thunderbolt? If yes, please look-up at these two fighters again. And by the way, a hole in a wing isn't a 100% mortal defect. However, a .50 round in the cooling system or the DB 605 of a Bf 109 take the Messerschmitt out of service within minutes. A 20 mm shell hit into a P-47's R-2800 might be survivable. There are some examples with a knocked out cylinders which made it back to base.
However, I stay with my comment that the P-47 has more firepower than a Bf 109 G-6.
And none of that means the 109 is of "flimsy consruction"...