Added after the fact: I mixed up the Ts and Zs in my description of the B&P (Baschiere & Pellagri wads. I have corrected the mistakes in the body of the post. That will teach me to go from memory. Thanks to MtnGun's PM for alerting me to my error. Just to be sure I don't mislead you again. The B&P T2 wad I'm talking about is called the 078 Lightning wad by ballistic products http://www.ballisticproducts.com/078-Lightning-7_8oz-12ga-wad-250_bag/productinfo/020L078/ and TUWT2 International Supersonic wad by Precision Reloading. The excellent B&P Z2 wads are called "Trap Commander" by BPI and B&P International Supersonic wads by PRI. The longer 7/8oz and 1oz wad is listed but not pictured. Again, sorry for misleading you.
Chip, just before I resumed shooting in my early 50s, I experimented with every wad and every hull I could find. I was planning on shooting Sporting and was reading about how you needed different loads and performance parameters for each type of shot. I bought special reloading books, different powders, wads, hulls and had at it.
I was shooting a fixed choke Beretta O/U at the time. I developed spreader loads, lots in between and a couple of long distance loads. There was, in fact, a measurable difference in PE between them. I figured, hey, I'm good to go. Well, the simple logistics of hauling 10 different loads around the Sporting course, and deciding which one to use when brought me back to reality.
The final ahah moment was shortly after I started shooting trap. Trap with a lighter gun is hard on your shoulder, so I bought a different O/U that I was told was suitable for trap. It was a Superposed. I started shooting it and retired the Beretta.
Naturally, I just had to pattern it, and did. To my surprise, amazement actually, all the different spreads I was getting from by Beretta barrels disappeared on the Superposed. Yes, there were still some differences, but no where near as pronounced as before. I eventually decided to stick with commonly available American components to simplify reloading and discovered that it really didn't matter what the load was (no extreme low or high velocity loads) PEs were pretty consistent. Patterns into a 30" circle at 40 yards were going to be around 82% for the U barrel and 86% for the O barrel. I have never since had a barrel that performed as well.
I bought a Beretta Gold E combo to replace the Superposed, and naturally I patterned it. Boy were those barrels finicky. It took a determined effort to find recipes that all three barrels liked. I did, but eventually sold the gun for other reasons.
I bought a used MX-15 that had been worked by Wilkinson. Naturally, I patterned it. It threw wonderfully even patterns with the three worked chokes. I was down to three or four "standard" loads at the time, but it worked well with all of them.
I traded up for a new MX-2000 Nickel with a 35" MX-15 unsingle barrel. This barrel initially had a problem with #8 shot, but a slight repair to the forcing cone cured that. I still wish I had kept that barrel. It smoked anything in sight, assuming I did my part.
I sold that barrel and bought an MX-10RS with matched 35/34" barrels. A couple of those did not pattern as well as I had come to expect from the 3 or 4 other Perazzi barrels I had owned, so I sent them to Kerry Allor for remedy. He did, and I shoot them to this day. They digest everything with aplomb.
I go through this history to illustrate my theory that there are intrinsically good and bad barrels. Good barrels tend to handle everything you feed them consistently. Bad barrels do not, and should be fixed.
With 20/20 hindsight, I now know it was a fools errand trying to develop loads my Beretta combo liked. I learned that lesson and almost immediately decided to have the MX-10RS barrels fixed. Now, it doesn't matter what I feed them, they just work.
That being said, and back to your original questions, there are wads that seem to consistently do a better job than others for specific loads. Let me say in advance that you will have to match hulls and basewads to use some of these wads, but if you do the results will be worth it.
If you shoot Riefenhauser hulls, or other straight walled cases with similar basewad heights, the the Gualandi Rex wad is the best you will find for 24g or 7/8oz loads in a 7mm basewad hull. With a 10mm basewad, you cannot beat the Gualandi Spark. The Spark is also a superb 1oz wad in a 7mm basewad hull. The Federal 12S0 also works well, but not as well as the others I mentioned. One I would absolutely stay away from (I know I'll get flack for this) is the B&P T2 wad. If you do pattern and chrono, you will not like your results.
The 12S0 is the finest, IMO, wad for 24g and 7/8oz loads in Federal GM and Rem STS hulls. Yes, STS hulls. You get an annular ring in the case, but the results are worth it. I use it up to 1325fps in GM hulls and 1250fps in STS hulls. It is also a superb 1oz wad in GM hulls.
For 1oz wads it is really hard to beat the TGT-12 in STS hulls or the Green Duster wad in STS or AA hulls. Don't ask why the Green Duster works better than the Win WAA12SL. I don't know why, but it does. I've already mentioned the 12S0 in a GM hull. Another superb wad, but really hard to find is the B&P Z2 series wads. The only place I know you can find the 1oz variant (longer legs) is Precision Reloading. If you reload Riefenhauser hulls for 1oz, don't even consider anything else. However, they are expensive.
There are good 1 1/8oz wads aplenty. The B&P Z2 with the shorter legs is first choice for any straight walled hull. Just be sure to match the leg length to basewad height. Other than Winchester wads, that for some reason or other never seem to work for me, there isn't a lot of difference between 1 1/8oz wads for American hulls. I used the 12S3 in GM hulls and the Fig-8 in STS hulls. I currently use the Fig-8 and Windjammer clone in STS hulls.
I currently only reload STS hulls (and an occasional Gun Club). I've found over the years that it pays to use wads designed for the hull you are reloading. That may seem simple, but if you read all the marketing BS out there, you are tempted to try them all. Don't bother.
As answer to your second question, I'll tell you the following. First, it is hard to characterize fps differences in wads unless you are shooting them on the same day. Air temp and pressure do play a part.
For some reason I was intrigued by Spolar's claim that if you used their Windjammer type wad with the super special, slick plastic, you would get 50fps more velocity with the same amount of powder you used with your old wad. Well, I just had to try it. I bought bags of the Spolar wad, the authentic Windjammer and the DRM Windjammer clone and compared them to my standard Fig-8.
Guess what. They all patterned the same and they were all petty much the same velocity. To pick nits, the Spolar was the slowest of them all at 1200fps, the Fig-8 the fastest at 1208 and the others were in between. SDs were all good. For some reason or other I didn't bother to pattern the original WJs. For the other 3, the Fig-8s had a 2% higher PE. So as far as I'm concerned, for my handicap load, it makes no difference at all if I use any of the four I just mentioned. In practice, i use the Fig-8. I still have a couple thousand DRM WJs that I bought when I couldn't buy Fig-8s. They'll get used eventually.
