I have recently bought a new one in Walnut as I didn't have an Air Arms PCP, and seeing one of these just had to have it.

Unfortunately I have only had the option of using it once so far, and tomorrow I am really looking forward to using it again.
My initial thoughts when I first used it are the same as Woodpigeons to be honest.

I did pellet testing on quite a blustery day at 25 yards and soon found the correct pellet. I obviously tried Air Arms they were pretty good as were the JSBs in 4.42 didn't like the 4.53s though and it also didn't like H&Ns.
I then tried the QYS FT domed grade in 4.50, Oh my god, no comparison to the others. Between the others, 5 shots left a group the size of a 5p, not bad. Then I fired 5 shots using the QYS and I was blown away, the group was one .22 sized hole maybe slightly larger, then touching that a single hole.
I repeated it twice to ensure they were that good, the following groups were pretty much identical. It has now got me thinking about trying them in my other PCPs even though the groups on the others are good, the S510R is outstanding.

Is it the pellet or is it the rifle. As much as I love my HW100, HW110, and R10 they are all very accurate but the S510 feels different. I think it's because of the adjustments to the cheek piece and buttplate, it really fits me the best. As soon as I shouldered it, it felt good, very good. It feels just wonderful to hold, everything about it feels right. Like Woody says it's so smooth to cock, it's so quiet. I bought a single loader from Rowan Engineering as I only use them on all my PCPs and that is as good quality as the rest of the rifle.

The filling gauge doesn't bother me as I have similar and used to that although it is deeply set, for me is not a problem. The trigger is very nice, but for me I just need to make it slighter lighter. The safety catch does seem strange where it is, but as I will very rarely if at all use it, again it's not a problem. On the cylinder it has a clear plastic cover on it, and wasn't sure to take it off or leave it. I had a good look at it when I took the stock off to oil the stock and decided for the time being to leave it on.

At the moment I can see this rifle being my favourite, which after having used the Weihrauchs and the R10 didn't think it would be. It has a lovely grain on the stock and over the last couple of weeks I have been oiling it. Not only does it now look even more lovely, it smells it too. I just love the smell of English Walnut oil.

The only downer of this rifle for me is the fact it's a left side load. I much prefer right side as I am hopeless using my left hand, and I get in a right 2 & 8 loading at times. I tend to lean over with my right hand to load it as I find it easier than using my left. My friend who shoots next to me keeps nagging me when he sees me doing that and is in the process of getting me used to loading cack handed. The other thing is I have a large sidewheel on my scope which I am unable to use.
I obviously knew which side it loaded before buying it, so it's only a preference thing for me nothing to detract how very good this rifle is.

So although, it for me is early days using this Air Arms S510R, I think it is an amazing piece of kit, I absolutely love it, I bonded with it straight away. It was love at first shot.
If my views change after I have used this more I will follow up this thread. I just get the feeling it certainly won't be negative ones.
Ade