"Without seeing the quotes in context, I can only assume the author was comparing the Browning .50 to other .50s - there's no way a 20mm cannon weighed less than a .50 cal machine gun. 100 rounds of 20mm ammo also weighs more than 100 rounds of .50 cal ammo, regarldess of type or nationality. So while the .50 Browning may be a heavy .50, it was (and is) still lighter than any 20mm cannon. "
He was comparing it to other weapons in the same class, the HMG class(and whear noted 20mm). Their are actualy several 20mm Cannons that weighed less than a .50 call Browining. While 20mm Ammo does weigh more it is considerably more effective than a .50 cal round, so you get more bang for your buck, each 20mm round is on average (depending on type) 2 to 3 times more effective than a single 50 cal round, over all the efficienty of the 20mm guns in terms of weight savings, production costs, maitance neads, total weapons system weight. and lethality make the 50. cal Browning by comparasion a very poor choce. Even amongst the contempory HMG clases it is a haevy weapon, and an inefeicent one for various reasions, look at the MG 131 for example bellow on the link I provided, or the Soviet UBK or UBS, far better weapons, in the same class.
"Regardless of the weight issue, you cannot simply say one gun was "better" than another. You have to look at the total picture, including the rest of the plane. The .50 was the perfect weapon for the US aircraft. They were designed (most of them at least) with it in mind. Putting 20mm cannons on a P-51 might not be "better" overall. You can't swap the weapon systems out without completely altering the effects on the aerodynamics, performace, etc. "
Shure I can say one gun was better than another, I would certainly not say the 50 call was the best weapon for US planes, since their are many that would of been better, Howeaver it was a reliable and effective gun, though at a cost, Weapon systems were often swaped, and yes their were negative results, 20mm were fited to P51's but I cant recall off hand why they were not adopted. The US planes were as you mention designed to operate the .50 call as it was the only weapon the US realy had to use for the reasions mentioned above.
"So while you may be correct in stating a certain 20mm cannon had more damaging effects on its target, you cannot categorically claim it was better than the Browning without looking at the total picture - which you have not done here"
Ya I have, I may not of painted it well enough though, see below...
See this page:
http://www.geocities.com/CapeCanaveral/ ... un-pe.html