I had an opportunity to try a variety of buckshot loads through a Patternmaster choke tube. For the benefit of the collective here's a compilation of my results with the Patternmaster tube.  I really am impressed with this choke, it shrunk my patterns 20-50% depending on the load. Weapon was a benelli M1S90 with an unmodified factory 18.5" bbl. Distance to the target was 20 yards. 5 shots fired in each group. Velocity is from the manufacturer specs and was not chronographed by myself. Pattern sizes rounded to the nearest half inch. Enjoy...

12 ga 2.75" Federal Premium 00 buck, 9 pellet, 1325 FPS, averaged 7" with a high of 9" and a low of 6". For comparison this previously patterned an average of 12 inches wide with an IC choke.

12 ga 2.75" Federal Vital-Shok 00 buck, 12 pellet, 1290 FPS, averaged 9.5" with a high of 12" and a low of 7" .

12 ga 2.75" Federal Power-Shok 4 buck, 27 pellet, 1325 FPS, averaged 14.5" with a high of 16" and a low of 13" .

12 ga 2.75" Remington Premium Hevi-Shot 00 buck, 9 pellet, 1325 FPS, averaged 5.5" with a high of 7" and a low of 5" .

12 ga 2.75" Remington Express 00 buck, 9 pellet, 1325 FPS, averaged 6" with a high of 7" and a low of 6" .

12 ga 3" Remington Express 00 buck, 15 pellet, 1225 FPS, averaged 14" with a high of 17" and a low of 10" .

12 ga 2.75" Winchester Super-X 00 buck, 12 pellet, 1290 FPS, averaged 10" with a high of 13" and a low of 11" .

12 ga 2.75" Winchester Super-X 1 buck, 16 pellet, 1250 FPS, averaged 8" with a high of 9" and a low of 6" .

12 ga 3" Winchester Super-X 1 buck, 24 pellet, 1040 FPS, averaged 8.5" with a high of 10" and a low of 7" .

Notes:
All of these loads were full power, no reduced recoil loads. The Remington Hevi-Shot provided the tightest patterns of the day and supposedly also penetrates better being harder and having a higher sectional density but at $10 a box is expensive to test more thoroughly. However the Remington 2.75" 00 Express also produced impresive tight patterns for a more reasonable $2.50 a box. Unfortunately the 3" 00 Remintgon Express was somewhat disappointing in the patterns, not to mention brutal on my shoulder and slower to bring back on target. Recoil on these tests seemed slightly less bothersome than when I last tested out loads using a standard choke. Perhaps it was a result of the porting on the choke tube, or perhaps I'm just getting used to it. When I get a chance to try some more types of loads I'll post their results as well.

Your post actually came up on Google when I searched for "patternmaster choke test".
Anyway, I got to try one today in my 1187 with 4 buck and 00 buck and the patterns were horrible.  Nowhere near yours.  Anyone out there have an idea why?  I'm at a loss.

Quoted: Your post actually came up on Google when I searched for "patternmaster choke test". Anyway, I got to try one today in my 1187 with 4 buck and 00 buck and the patterns were horrible.  Nowhere near yours.  Anyone out there have an idea why?  I'm at a loss.

Were you using the same brand and style of ammo as the previous person?

Define horrible- overal size of pattern too large?  not evenly dispersed?

Is you gun's bore dirty, pitted, have wad fouling, or any combination of these?

I've had decent luck with Remington and Winchester buckshot for good patterns.  The buffered Winchester shells are really good.  Copper-plated buffered buckshot is even better.  Sellier & Bellot works in some guns, and is terrible in others.  I've also had mixed results with PMC.

The same ammo will perform differently in different guns, even if they are the same make and model.

A choke is only part of the equation.  Ammo matters.  The condition of the forcing cone can make or break a pattern.  A dirty or neglected bore can ruin patterns too.

Ammo type does still matter with the patternmaster. It's claimed the tightest patterns will be achieved with the largest buckshot. The patternmaster tube has a row of teeth that grabs onto plastic wads and delays them momentarily, letting the shot charge continue without getting dispersed by the wad or gasses blowing past. . There will be very litle, if any improvement with the cheap import buckshot like Wolf or S&B because they use unbuffered, uncupped fiber wads which will not grab the teeth the same way the plastic cups will. The fiber wads just get shredded by the teeth, and the buckhot is soft and easily deformed.

I was using Remington Express 4 buck and Federal Classic 00 buck.
Horrible means too large, unevenly dispersed pattern.
No pitting, I do appear to have some dirt (possibly plastic) around the forcing cone.  What's the best way to clean that out?  My bore brush isn't big enough.
A dirty forcing cone can make that big a difference?

Quoted: Were you using the same brand and style of ammo as the previous person? Define horrible- overal size of pattern too large?  not evenly dispersed? Is you gun's bore dirty, pitted, have wad fouling, or any combination of these? I've had decent luck with Remington and Winchester buckshot for good patterns.  The buffered Winchester shells are really good.  Copper-plated buffered buckshot is even better.  Sellier & Bellot works in some guns, and is terrible in others.  I've also had mixed results with PMC. The same ammo will perform differently in different guns, even if they are the same make and model. A choke is only part of the equation.  Ammo matters.  The condition of the forcing cone can make or break a pattern.  A dirty or neglected bore can ruin patterns too.

Quoted: Horrible means too large, unevenly dispersed pattern.

You mean keeping all the pellets on a 4' X 8' sheet of plywood at 25 yards isn't good enough for you?

I saw his pattern, and he could keep all the pellets (15 pellet 00?) on a standard sheet of poster board (2' X 3' perhaps?) at 25 yards, but the pattern was probably 24" across with clusters of 3-4 pellets spread out.

Quoted: I was using Remington Express 4 buck and Federal Classic 00 buck. Horrible means too large, unevenly dispersed pattern. No pitting, I do appear to have some dirt (possibly plastic) around the forcing cone.  What's the best way to clean that out?  My bore brush isn't big enough. A dirty forcing cone can make that big a difference?

Bore brush isn't big enough?  Is it worn?  You might need to get a new one.  It should make good contact with the forcing cone.

When the wad fouling starts, it seems to compound itself.  It cakes and builds.  Any buildup, marks, scars, whatever, will indeed effect the pattern.  The forcing cone is important.  If it is rough, and/or short it can scar or flatside the shot.  This is what produces the "flyers" in a pattern.

There's several different methods to get a shotgun bore really clean.  This is about the quickest-
Get a dowel rod, about 3/8" diameter and cut a slot in one end. Measure the barrel and compensate for the choke tube (leave a choke tube in the barrel for this to protect the threads!).  Put a piece of tape on the rod to mark the barrel length, minus the choke length.  Take a piece of 0000 steal wool and unroll it.  Insert it in the dowel slot and wrap the end.  You want a ball that will be a little snug inside the barrel, but not to tight.  Chuck the rod in your drill.  Put the drill in Reverse; this will keep it from unscrewing the choke and boogering the threads.

You can also use a cleaning rod and a smaller gauge brush wrapped with steal wool, if you can get the handle off the rod.  If it is a rod that screws together in sections, you can't run the drill in reverse.  This works fine, just be careful and pay attention to the choke tube, and mark the rod.

I've tried solvents and different oils.  The best seems to be Flex-hone honing oil.

Clamp the barrel down.  Put 5 to 10 drops of honing oil in the chamber.  Spin the rod in the chamber, then very slowly start moving it in to the forcing cone.  As you start to move the rod in, you should feel some resistence.  Progress very very slowly forward, since the forcing cone is the suspect area.  Keep going forward till you have run through the whole barrel.  Start withdrawing the rod at the same speed.  Check the barrel for heating while you're doing this.  Warm is okay, but I don't like getting my barrels hot.  Spend some time going back and forth through the forcing cone area.

Run patches or rags through to remove the oil, debris, and slurry.  Clean and oil the barrel as usual.  The barrel will now be extremely clean, and probably have a better surface than it ever had.

For optimum patterns, the forcing cone should be 1 1/4" long.  The forcing cone should be honed and the bore should be honed.  And a final polish will steel wool as described above.  The hones are available at Midway and Brownells.  A honed and polished barrel are less suseptable to plastic fouling and rust.  They are also extremely easy to clean.  The patterns will be dramatically improved and the more evenly distributed.  

I can hone the barrel for you if you'd rather go that route.

I hope this helps.  If I can be of further assistance, just ask.

Quoted: You mean keeping all the pellets on a 4' X 8' sheet of plywood at 25 yards isn't good enough for you? I saw his pattern, and he could keep all the pellets (15 pellet 00?) on a standard sheet of poster board (2' X 3' perhaps?) at 25 yards, but the pattern was probably 24" across with clusters of 3-4 pellets spread out.

Hmm, for a fancy choke I'd expect more.  My Rem 870 18" fixed IC choke barrel (honed and polished) produced this-

Remington 00Buck 2 3/4" 9pellet
12yds- 10" or 8 1/2"W x 9"H
12yds- 7" or 7"W x 6 1/2"H
25yds- 24" or 24"W x 21"H
25yds- 21" or 15"W x 21"H

Winchester 00Buck 2 3/4" 9pellet, buffered
12yds- 10" or 9"W x 10"H
12yds- 9 1/2" or 8 1/2"W x 9"H
25yds- 21 1/2" or 19"W x 21 1/2"H
25yds- 22 1/2" or 19"W x 21"H

It seems that 11-87 barrel needs some work.

The other thing to try is an extended skeet or steel choke tube with a Modified (mid range) constriction.  Carlson's

Here's some tests with different chokes and the Extended Steel Mid Range (modified choke) in an 1100 21" barrel-

Remington Express 2 3/4" 00Buck patterns @25yds
Improved Cylinder - 18 1/2" or 9"W x 16"H
Modified - 20" or 15"W x 15"H
Full - 13" or 9 1/2"W x 12"H
Modified Extended - 11" or 10"W x 8"H

Since the Steel Extended Modified choke seemed to be best, I left it in and tried some other ammo.

S&B 2 3/4" 00Buck
25yds - 17" or 13"W x 17"H

Federal 2 3/4" #4Buck
25yds - 14" or 14"W x 12"H

Winchester 2 3/4" buffered #1Buck
25yds - 19" or 16"W x 15"H

Thanks for the info 2guntom!  I picked up a 3 piece bore brush (previously only had Otis kit) and some cleaning solution that's supposed to work on plastic.  If that fails, I'll go with the steel wool.  I will get it clean and I will retest!
Regarding the patterns I got, at 25 yards, the 00 pattern was odd.  The pellets grouped together, one group of four, another of three or so, then another wider group of about 6 or 7.  None were near the center!
I'm glad I'm getting this sorted out now, turkey season is right around the corner.
Thanks!
Jim

You bet.

Let me know how it goes.

Good luck with gobbler season.  Post some pictures of your hunt.

Ok, I cleaned the heck out of my barrel and chokes today.  FYI, Outers brushes are larger diameter than Otis, but won't stay together if you try to spin them.  I used the cordless drill and the new cleaning rod and got the bore spotless.  I guess by "honing" you mean you smooth out that rough area in the forcing cone?  After that, I ran down to M4Madness' place and fired one round of 00 and one round of 4 at 25 yards.  The improvement was quite noticeable.  The groups were more evenly distributed and tighter, but still not as spectacular as what has been posted in this thread.  I'd ballpark it as all pellets of 00 in a 24" circle at 25 yards.  I need to bring the target in and measure.
Of course, now my previous tests of various chokes with 4 buck are completely invalid.  
The 4 buck did pattern pretty well, but nothing to write home about.

That's great!  It sounds like you are indeed making some good progress there.

I used to spin brushes in the bore, but with the experience I've gained from it, I don't recommend it.  The brush wrapped in 0000 steel wool is for polishing or cleaning stubborn spots.

By honing, I mean using a hone.  There are 2 for the forcing cone, and 2 for the bore.  I recommend using all 4, then doing a final polish with the steel wool using the honing oil.
FC Hone Medium
FC Hone Fine
Bore Hone Medium
Bore Hone Fine
Honing Oil

Do you have any other chokes?  If you have a Modified choke, try it against the fancy choke and compare results.

.