I have a new Jacket and not sure if I have the buttons to tight on not is that any rules on how fitting your jacket should be?

Danny, as far as I know there are no specs in the indoor rules regarding this but if you are going to shoot outdoors this ISSF rule comes into play when shooting Championships and in particular designated matches and other "ISSF type" matches
Here is rule 7.4.7.2 which refers:

"Closure of the jacket must be only by non-adjustable means e.g.
buttons or zippers. The jacket must not overlap more than 100 mm
at the closure (see Jacket Table). The jacket must hang loosely on
the wearer. To determine this, the jacket must be capable of being
overlapped beyond the normal closure by at least 70 mm,
measured from the center of the button to the outside edge of the
button hole. The measurement will be taken with the arms at the
sides. A measurement may be made either manually or with an
ISSF approved overlap gauge with a tension of 6 kg to 8 kg. The
area surrounding the button hole is limited to a maximum of
12 mm, and this area may exceed the permitted 2.5 mm thickness."

The rule is a good guide for indoor shooting as well. I beleive that having the jacket done uo too tight indoors is no real advantage for prone shooting and I have shot without buttons without any real disadventage, of more importance is the fit of the jacket across the shoulders and also on the arms where you don't want too much bulk and should be the correct length so as not to interfere with other gear or touch the rifle etc

While we are on the subject of fitting your jacket, here is a lttle tip
I"ve seen over the years shooters wearing all sorts of different clothing under their shooting jacket with varying degrees of success.
As we al know, the fit of the jacket is of great importance and I've seen shooters make do with a jacket that is too large for them and they do this by wearing extra clothing under the jacket to bulk things out and make it fit. This may seem to make things fine but in my mind if you do this you are not doing yourself any favours. Sure the jacket seems to do the job but what happens is the jacket can move about over the bulk of that extra clothing and cannot be a firm fitt to the body, the upshot is that the tension applied to the jacket by the sling trying to support the shooter inevitably pulls on the jaket which will move over that extra bulk and your position goes all loose during the match and the support normally associated with the sling/jacket combination is lost. As I have said elswere it is important to get that fit across the shoulders right and by that I mean firm without being too tight or uncomfortable and use a light(ish) undergarment such as can be bought from most suppliers (for a while now I have used a Polyprop long sleeve thermal), the trick is to get a seamless sleave or make sure that the seam dosen't sit under the elbow cause that will hurt.
Steve McNatty used to make club jackets that had an adjustable strap across the sholders to help cater for different sized shooters in a club situation but these are illegal in curtain situations and are often frowned upon for anything other than club shooting but great for fast growing kids. (ISSF regs prohibit the aplication of such adjustments)