I have been trying to get my AK to group. Removing the cleaning rod and slant cut muzzle brake tighten the groups considerably, but my best is still 3"x2" at 50m from a sandbag, using both irons and a red dot. Groups slightly better with the red dot. I was using Tulammo. I have no issues from other rifles.
What else can I try?
The main thing which has already been mentioned is to try shooting some better ammo. Just about any brass cased x39 ammo produced in the US will be be better than steel cased Tula or Wolf, the only really positive things to say about that ammo is that it's cheap and readily available. If you're expecting it to group well adding a scope with some magnifification will probably help too.
For instance as a comparison at 100 yards here's an iron-sighted Chinese AK that I just bought shooting steel-cased Wolf 122 grain HP off the bench in comparison with my most accurate Ruger 10/22 using a scope.
(I wasn't comparing them at the time, I just brought out that AK right then since I just bought it and I always take out that .22 pretty much no matter what. I'm just an incorrigible target saver and when I saw the groups between the two I had to laugh a little
)
That Ruger 10/22 is really accurate though and besides the scope (a Nikon 3.5-14x40 Mil-Dot scope with a Weaver base and Burris rings) it has a match grade Green River bull barrel and a Bell and Carlson Anschutz stock and then for the ammo I'm just using Federal lead Auto-Match (40 grain lead solid)
That's literally the first time I've ever fired that AK though. I just bought it for $650 (thinking that was last Military style centerfire semi-auto that I was going to be able to get before Hillary got the crown) and I'm taking that .22 out quite a bit.
If it's a used rifle and its dirty or it was dipped in cosmoline or some other preservative cleaning it's barrel very thoroughly might help, better ammo will help, using a scope with some magnifification might help, a better trigger might help (
***Link for AK trigger by ALG Defense***), more practice with that rifle might help, you might have just had a bad day and so on.
Just saying, every little bit helps.
That's also a crappy group for me even considering that it's an iron sighted AK using crappy ammo. The next target I put up looked a little bit better at the same range using the same rifle, same ammo, same position, same mag ... Same everything.
Its just that I warmed up a bit and became more accustomed to the rifle.
Try cleaning the rifle, try using better ammo, maybe throw on a scope with some magnifification and maybe being a little more deliberate about it and practice good fundamentals and I'm betting that you'll have better results.