We had a guy in our agency get it done and it was pretty pricey for the results. I didn't really notice too much of an improvement. It may just be the ammo we use though.

I fired a 1300 Defender that had the Vang comp job.  I had fired it with full power slugs and  full power #4 buck prior to the Vang job.  The #4 buck kicked pretty good, but the slugs were downright painful.
heh
I've I had one, I'd do it.

I will second what JPPJ says. If you use the federal Tactical 00 buck and slug the recoil is pleasant for a gauge. The only disadvantages are the increased noise and muzzle flash. I have a question about the K-9. Does it have the lengthened forcing cone and is it back bored? These two things help reduce recoil and improve the shot pattern. If you have these two things already maybe Vang will not charge as much for the porting only job. It would be worth asking him.

Vang comp is nothing new to the shotgun smith, you can have any good smith do a modified forcing cone, and the job result in a much better finished product then Vang comp. Vang is a great guy and I m not try to short change him. but he just took a old trap shooter trick and add a mag port in front of the barrel.  Vang is the first to add this feature to the tactical application.  I personally don't like the magna porting in the muzzle but the forcing cone work is great, the pattern is amazing as the range begin to extend.  

one thing, Vang don't polish the in ternal after his work is finished.  The Vang barrel I had done gets dirty very qucikly.  the other barrel I had(After I learn the difference, and had a local gunsmith do the forcing cone) is polished and I have shot five hundred plus and have not send a brush down the bore yet.  some gun scrubber and everythign gets flush out.

I hear Vang is contracting Bar-Sto to do their 870 barrels.  this might yeild a better product.  I will have to see when Stony bring the product in town.  

I have an 870P that has the forcing cone reduced.  A few months ago I patterned several different shotguns including a complete VC 870.  Felt recoil was reduced a bit from stock, but the biggest improvement was the pattern.  IIRC, the VC pattern was about 1/2 the size w/tactical loads ie maybe 22-23" at 25 yrds for a stock gun and the VC would be at about 12-13.  I don't remember the numbers exactly, but we checked em at a variety of ranges and it was consistently about 1/2 the size.  Just the forcing cone on my gun didn't make that much of an improvement over stock.

If you are building a gun for duty use and you like using buck then definitely go for it.  Depends on how much you're going to use the gun versus cost/value to you.  I would do it.

Vang Comp pattern test results here...

www.vangcomp.com/test_results.htm

There was a before and after pic showing a much tighter pattern after a Vang Comp mod but I couldn't find it on the website.

AHA!  I knew you weren't finished with that project Runner!  Everything I've read on them says the patterns improve greatly when Vang works his magic.  I tried to have the same thing done to the afore-discussed Benelli, but he said the barrel was to thin on the Benelli's.  Usually, when I ask a question like this, it's already a done deal.

 GO AHEAD AND DO IT  

Rabbit9 I believe that the improved pattern comes from the back boring. From what I have been told it changes the choke of the gun farther down the barrel prior to the muzzle. I agree with you that there is a much better patterning from this work. I guess that is why Browning does it to all of their over and under guns.

That Dennis is a good salesman, not that you needed any help talking yourself into getting a new gun.

Wave whats the deal? Vangcomp has an 11-87 that is ported. Is your barrel different being a Wilson.

I'll just let you shoot my Ithaca 37 first.  Everything after that feels just like a .22.

Waverunner, you got a Wilson for Christ sake. You don't need to do anything else. That's why You paid big buck for it. Save your money on something else.

Quoted: Quoted: Waverunner, you got a Wilson for Christ sake. You don't need to do anything else. That's why You paid big buck for it. Save your money on something else. Don't get me wrong...I absolutely love it, I'm just never satisfied and felt maybe I could make it even better. Yes I am crazy sometimes!

You're not crazy - It's just a DISEASE!!!