The P82 was conceived as a bomber escort late in the war and six .50cal appeared to deemed suitable for knocking down German fighters. Unfortunately it didn't get operational until about 1946. I have a photo somewhere in my collection of a prototype concept with a large gun pod in the center between the two fuselages with talk they were going to put an extra eight .50 in that, also a heavier cal weapon 57mm size but again never got past the design stage over a drink in the club. The P82 had some limited success in Korea escorting B26 Invaders and shooting down piston engine Yak's but with the appearance of the Mig15 they were rendered obsolete in the bomber escort role. About this time the Russians began flying a knock off of the B29 that they reversed engineered called it the Tu4 so the P82 was pressed into service as an interim all weather air defense fighter till the arrival of the F94 and the F89. So with 10 years they had been rendered surplus to requirements and obsolete by the Jet Engine and by the mid 50's most were gone.