It looks like Russia is moving more and heavier artillery into Syria in its fight against fundamentalist Islamic terrorists (and opponents of the Assad regime). That's not surprising, of course: the former Soviet Union placed immense emphasis on artillery, with Stalin calling it "the God of War". The Soviets also gained experience in the use of artillery in counter-insurgency warfare during their occupation of Afghanistan. All those lessons appear to be coming into play now in Syria.
Here's a video clip of one of Russia's modern rocket artillery systems, the TOS-1, in action in Syria. Note the thermobaric warhead explosions on the hillsides, and the way the rockets are spaced to cover a wide area - typical reactive fire to 'targets in the open'. The blast and overpressure caused by such rounds will kill anyone in the vicinity by collapsing their lungs, even if the fireball, shrapnel and debris don't; and the same effects will collapse buildings if the round explodes inside them. Watch in full-screen mode for best results.
I reckon the Russians must be reorganizing the Syrian Army's artillery arm as well. It's already well equipped with Soviet-era artillery systems, although they probably needed some intensive maintenance and their crews would probably have needed re-training. In an interview with a news program a Russian officer, Konstantin Sivkov, had this to say.
The success of the Syrian Army in the first day offensive in Hama province towards Idlib was partially due to the method that is called “fire wave”. This means very dense artillery shelling, using 300 or more artillery pieces per 1 km of the frontline. The fire is aimed at the defense lines and is moved forward as the troops advance. This method consumes a lot of ammunition, but it is very effective in getting through fortifications. This allowed the breakthrough via the enemy defenses. I would like to point out that after that there was no information about the use of such a concentrated artillery fire. This suggests that the Syrian forces used up much, if not most, of the ammunition they had, including those supplied by Russia. Apparently, now they don’t have enough ammunition for adequate artillery support of the troops. That would explain why the rate of advance was greatly reduced.
There's more at the link.
That sounds very like Soviet-era artillery doctrine to me. I daresay many of the ships and aircraft pouring into Syria from Russia are carrying more ammunition.