SKS not fully ejecting

Yugo SKS, Tapco T6 stock

I find this problem somewhat troubling in that it will be fine for 4-5 shots, then the next 3 casings will almost eject and the bolt will close on them. (is this called stovepiping?) Could it be an issue with the ammo? The gas system? or could it be my form? (similar to limpwristing a handgun?)

Any ideas?

Cleaned about a month ago, but I haven't shot it much until this past weekend. Put the T6 stock at the same time I last cleaned it, everything got put back together properly.

Bought it about 4 months ago, and ya I tore it down and cleaned it up, there wasn't really any cosmo, as it was a shooter grade... I put about 60 rounds of Wolf FMJ through it when I first bought it, without a hitch. No one is selling wolf FMJ around here at the moment so I'm stuck with HP's, although I beleive I have a box or two somewhere around here.

^Thanks

Will do! I was hoping not to have to buy anything... aw well, whats another $20

Just to update everyone, the problem was with the ammo! I'am very pleased to find this out, because I don't have to spend anymore money. (On parts at least)

The WOLF hollowpoints are garbage in both my SKS and my brothers AK, they jam in the SKS about 75% of the time, and in the AK about 15% of the time. Wolf FMJ's run perfectly through both rifles, flawless!