There is a difference in tool quality but the off-center holes are probably caused by the bit encountering a stone in the concrete just below the surface. The aggregate is harder than the cement and will cause the bit to drift to one side.

My experience anyway.

Difference between Milwaukee and Ryobi?
Corvette vs Vega.
Ford F250 pickup vs Pinto Wagon.
Get the picture?
Perhaps you were kidding when you compared one of if not the best hammer-drill on the market to one of if not the worst brand hammer-drill on the market.

Mine is a Ryobi.

I had a feeling this hammer drill wasn't cutting it, as far as puching holes in concrete.

Since it's a Ryobi, maybe that's why.

I totally disagree that Ryobi is that much inferior. I use Ryobi 18V and did heavy duty work with it. I did earthquake retrofit for 4 house, I had Milwaukee hammer drill, it did not drill down the foundation very well and I had to buy a Borch rotary hammer.

The first question is how big is the Milwaukee compare to the Ryobi, you can't just compare names, compare the amps. I don't think my Milwaukee was bad, I was too cheap at the time and bought a smaller one. I am sure if you buy the same size Ryobi, it will be close.......at least 80 to 90% of the power.....for a lot less.

I have the finest tools, I paid so much for a set of 18V Dewalt tools that broke on me after I did retrofit only one house. I bought the Ryobi set because it was cheap and I consider those as dispossable. It has beem 3 more houses since and the first Ryobi drill is still working!!! I have complete set of Ryobi 18V and none fail. I burnt out 2 batteries which is onlt $49 dollars to replace. Try other brands!!! I really use it. I drove 5/16 4" bolt into wood, used it as nut driver. I drive it so hard I can smell the burn, but never die. It can break the head of a 5/16 bolt if you are not careful. That is Ryobi for you!!!!

I have an expensive 14V Borch drill upstair for show and I kept my set of Ryobi in the garage for real work!!!

If the drill hole step sideway, you must have hid a reed bar!!!, Even my big rotary hammer will step sideway. NO way around this one. If you HAVE to drill at that spot, you have to buy a special bit that grind the reed bar out. I saw those bit before, don't know the name.

Yungman, I disagree with you on this point. Cordless drills are the one tool that I believe you get what you pay for. After going through many cheapo drills including Ryobi I went with more expensive brands like porter Cable and Makita, finally ending up with a Milwaukee. This drill has 650 inch pounds of torque. The chuck is heavy steel and the Li-ion batteries are long lasting , very light, charge quickly, and have almost twice the capacity of the Ryobi. The hammerdrill part works fantastic too.

I have the old non Li-ion stuff. I can tell you I beat the hell out of it. As I said, I use it for screwing 5/16 and 3/8 lag screws and tighten 5/8" nuts. I really use it. I have complete set of Dewalt and all the batteries died. I never say Milwaukee is bad. It is very good. I just say Ryobi is not junk. I cannot think of anything that tax the drill and other tool more than doing earthquake retrofit work. I don't have a battery hammer drill, so I can't say about that. I use a rotary hammer that drill 3/4" and 16" deep into concrete, battery won't do it.

I have Makita stuff too. Of cause, they are better than Ryobi. I just say Ryobi is not bad. I can tell you a lot of contractors use Ryobi tools now a days. It is only 1/3 the price fror 80% of the power!!!

How's the bit? A damaged tip will allow or cause run-off.

The special bit is a rebar cutting bit.

Make sure get a commercial quality bit. I started out using Craftsman bit on the Milwakee, the moment it hit the rebar and jerk the drill, the bit was bent at the shank!!! After I bought the Borsch, I use only Borsch bit and never broke one yet after earthquake retrofit 4 other houses.

If you hit a spot that the drill start jerking and twisting you, stop, try pushing lightly and drill for a little bit, if it don't drill any deeper, you must be hitting a rebar, no drill with ordinary bit will drill through the rebar, you either have to change a location or get the rebar bit to drill through it. I am not sure that is a good idea to cut the rebar bar because it will weaken the structure.