Athos, I'm 38 and never used to be a big distance squirter. I started doing some research and found some of the best supplements over time that really made a difference for me. I started with a calcium/magnesium/zinc tablet and selenium. These all work together for the natural production of testosterone production in the body. I added 3 x 1000mg capsules of lecithin. This really made a big difference and really helped with the volume. If you can manage a little stimulation, without ejaculation, approx 1 hour before you have sex, it seems to really increase the volume and intensity of the orgasm. It's almost like a warm up before you exercise. Make sure you stay well hydrated. Time between ejaculations is a huge factor also.
I've tried several of the "volume" pills and have found a couple that workeed for me. Magna RX (which I just saw the other day is now being sold at Wal-Mart) worked pretty good for price - $25. The best I found was a pill called Xplosion. It's about $40 bucks for a bottle. That stuff gave me some huge volume and some huge distance, both being better than when I was in my 20's. I would only take it for a couple of days in a row before I knew I was going to have a hot date night with the wife. Their directions say the more consistent you take it, the more improvement you can expect. I'm not sure how much I believe that due to the need to cycle anything that has messes with your hormones. I used to get it at a local adult book store, but they don't carry it any more, so I tried another brand and it seems to work ok. I can't remember what it's called, but I think they all have pretty close to the same ingredients; ie. maca, horny goat weed, tribulus, yohimbine (I don't care for this stuff), arginine, and a few others. I think the key is to find the one that works best for you.
One last little thing, I've seen pornstars do this. Right at the point of ejaculation, squeeze the uretha at the base of the glans just for a brief moment in time to build a little pressure. Concentrate on giving a forceful kegal, and release when you feel the pressuremoving up to the tip. Just make sure your not pointing at anything not cum proof...like your wife's eye! lol