Just a little update for those of you that may have run into the same issues I have.
First, the 7.62x39. I replaced the magwell with the magwell for AR pattern mags and I'm using duramags. When running hollow points, I found that if I grabbed the rifle in a manner where I hit the mag, thereby causing the front of the mag to dip down, the rounds would impact the flat on the lower portion of the receiver and it would just stop. You could remedy it quickly by just rocking the mag forward and tilting the rounds up a bit and then it would feed. This didn't happen with ball or soft points, just the hollow points, although it did cause some rough feeding.
I considered 2 remedies. The first was easy. I just applied masking tape to the front of the magwell, preventing the mag from tilting too much, but this seemed like too much of a bandaid. Instead, I opted for a more permanent solution. I pulled the action from the stock, put it vertically in a vice and took note of the "trail" that the rounds were leaving on the feed ramp and I used that as a guide. I used a dremel to cut 2 feed ramps similar to what you'd find in an M4 AR.
No more feeding problems and the action almost cycles in a manner that you could describe as slick. Now that I have over 500 rounds through it, the bolt operation has slicked up nicely. No more binding at all, no matter how I hit the bolt. The only thing that keeps it from being truly smooth, is those little bumps the mags have in them inside the feed lips. I was gonna grind them down a bit, but figured they're probably there for a reason. I may try grinding them down on one anyway, just to see. I can eat $12 for the cause.
Now, for the .308. I really don't know if I got a special one or what, but mine is super slick. I can't even bind the bolt up when I try. The only problem I'm having is with PMags. Inserting the mag on a closed bolt is difficult. Operating the bolt, you can feel the magazine rubbing on the bottom of the bolt. I just put some fine sandpaper down on a flat surface and ran the tops of the feed lips across the sandpaper a couple of swipes at a time until I didn't feel the bolt rubbing anymore. Not having any problems at all with the Ruger mags.
Now, I just need to find ammo that these rifles like. I don't know what I was thinking, but I bought a bunch of PPU soft points for both and they both hate 'em. The 7.62x39 will put Russian steel case into an inch or less at 100, but the PPU SP, 2" at best. The .308 hates the 160 something grain SP. 3" at best, but it'll do 1.5" or so with the 150gr SP. I guess what I hoped would be my hunting ammo is gonna become plinking fodder.
I have a little stash of Wolf hollow points for the 7.62x39 and I ordered some Hornady SSTs. These Rugers supposedly love that stuff.
A buddy of mine at the range where I shoot, who sights in rifles told me that he hasn't seen a Ruger .308 that wouldn't do MOA with Hornady Whitetail, so I ordered some of that. We'll see. I hope mine isn't the first he's seen.