I'm not buying it. if you look at the one photo posted with the article it doesn't agree with what he is trying to assert. For one thing the author mixes up mm and caliber. A 30 caliber round is 0.308 inches in diameter and a 30 mm round is just that 30mm in diameter or 1.1811 inches.
30mm does happen to be the size of cannon on the Mig-29 flown by both the Russian and Ukrainian air-forces. The picture does show a couple of holes made by a round projectile but not large enough to be made by 30-mm cannon fire. Also it shows no indication of any metal being bent outward. The idea that two jets would fire at the same piece of metal from opposite sides of an aircraft while it is traveling at 550mph and hit it at about the same time is something only a movie studio could produce.
A much more believable analysis is here with with the same picture plus others shown in context. You can see that a missile contacting the side of the cockpit and exploding would be carried inside the cockpit while the explosion is happening so shrapnel and debris of all sizes would be traveling in all directions.
https://www.metabunk.org/threads/mh17-e ... -etc.3997/