This may be asking for an impossible conclusion but I really would appreciate some first hand comments on the best AR15 match sight combo. On my A4 I just mounted a Redfield Palma rear with Gehmann 530 (optics and diopter) and an 18mm globe front mounted on a Lipski. Today I went to my closest 600Y range in Nashua NH and shot this combo for the first time. This combo isn't very good. The Palma seems less than repeatable, the globe front seemed a bit cluttered compared to a simple post front, and the adjustable features of the Gehmann seemed to make the whole business too complex. What is the best rear sight for the money? Does anyone use a psot front for match rifle shooting? Jim Owen's book speaks in favor a front sight lens and against a rear sight lens...any thoughts?
TIA
CC

You're right that the Palma isn't up to the job.  The Cadillac of rear sights is the Warner, but it's expensive with a long wait for delivery.  There are high-quality rear sights on the market from Centra, RPA, Phoenix, REG, and PNW (I've probably managed to leave somebody out) that will do the job well.  I prefer the Centra for its repeatability/accuracy,  small size, light weight, vernier scales visible from behind the sight, and good workmanship.

Most shooters prefer a 22 mm globe, but I happen to like an 18 myself.  You may want to get another mount for the globe that's repeatably adjustable for elevation - that will save wear on the rear sight and allow you to maintain a consistent cheek weld without adjusting your buttplate, especially at 800-1000 yards.  I shoot a spacegun and like the Medesha BBB for its simplicity, repeatability and strong construction, plus not having to turn the muzzle to 3/4" to mount it.  The most popular front base is probably the RPA ladder, but it seems a bit flimsy to me.

An adjustable front iris is almost a necessity since the apparent size of the bull will change with distance, especially at ranges greater than 600 yards, and offhand usually works better with a larger opening than is used for sitting or prone.  I prefer an Anschutz Vario-Swing iris set to have a single crossbar that I level for offhand (I use an inward cant of ~20 deg) and an external bubble level to help me keep the rifle level in sitting and prone.  I don't like having the level inside the sight tunnel, and a crosshair is distracting and may interfere with reading the number boards.  The Vario-Swing lets you rotate the crossbar without having to loosen and tighten a locking collar.  There are irises that have no crossbar; they use a glass support, but that can be a problem in the rain.

A rear iris lets you compensate for lighting variations and is very useful.  Many people have day-to-day variations in their vision and find a diopter in the rear very helpful, and the 1.5X magnification that comes with it is a plus.  Polarization is of little use as far as I can see and I always use a light amber tint (sometimes called a blue blocker) in my glasses, so I see no need for the complexity added by putting them into my sights.

A magnifying front lens won't work for most people at Highpower distances (200-1000 yards) since it puts the bull even more out of focus than it already is; they're more commonly used for  air rifles and smallbore at distances of 10 meters to 50 yards.  I use a -0.25 diopter front lens to be able to see the bull with good contrast at 600-1000 yards, but it has the disadvantage of making the target appear smaller - don't use one unless you must.

a 22mm front globe may help, no level, with thin correctly sized inserts.  i use a lyman #93 globe w/shaver aperture inserts, level on gas block.

I haven't tried this on an AR match rifle, so keep that in mind!

Previously I had an RPA Trakker rear sight w/ a basic Gehmann 510 (no diopter) rear iris, and I honestly can't recall if it was an 18 or 22mm front RPA ladder sight on a bolt action match rifle.  I had all sorts of fits w/ that gun... finally sold it and went to the Service Rifle (kinda bass ackwards, but I could shoot it better w/ the post).  Ended up having some problems w/ that as well, going w/ too big of a rear aperature causing me to lose depth of field... I could see the front sight, and the target at 200/300, but not at 600.  Pretty much the same problem I had w/ the aperature sights on the bolt gun.

Recently set up another bolt gun w/ match sights... Porter front w/ 22mm Centra variable aperature, level, etc. up front, PNW sight w/ Gehmann 530 in the back.  This setup was a major revelation for me, as I can finally see the front sight clear/sharp *and* the target reasonably well defined as well... and so far in practice it shows in my scores.  

The 530 does take some fiddling to get used to, in my experience.  Basic use of the rear aperature is close it all the way down, and while in position looking thru the sights, open it up until things start to suddenly get a bit brighter.  For me that is the point where I start to loose a little definition of the target image, and is the point I need to either stop or close it just a tid bit back down.  The diopter was a little harder to get dialed in, basically I dialed it all the way to max, all the way to min, back halfways so it should be kind of centered, then start tweaking to where the front sight is reasonably sharp and the target nice and black... figure if I can read the number board clearly @ 600yds it's pretty good to go.  While Jim Owens is much more experienced than I... keep in mind that those books are more than a couple years old... things change in that amount of time, and many HP shooters no longer have the inhibitions about Smallbore equipment that they used to.  Mr. Tubbs uses a rear diopter, obviously w/ some success.  That said... AR's w/ the *forward* recoil of the bolt carrier mass tend to be kind of hard at times on semi-delicate things like diopters and scopes reticles, etc.  

The front diopter enjoys some popularity in the long range venue, because it magnifies the tiny bull @ 1000yds.  It also magnifies any atmo distortion (mirage) as well, so it's not always a good thing, and front/rear diopters at the same time are not legal.

I've though more than one about getting a 18mm front sight (guess that original RPA musta been 22mm) and putting in a post just for giggles as I seem to shoot a little better w/ my Service Rifle front post than I do w/ the aperature at this point... kind of an expensive experiment for me, as a new 18mm RPA ladder is $150-175, and I was only ever able to find one post set up for a 22mm sight... I think they were from Centra or Gehmann, adjustable for cant (!) and damn expensive... $30-40 a pop (per width, screw-in inserts).

Just my $0.02 worth...