Vang Comp performance and Chokes tubes.

[W.R.Buchanan]

Hans Vang was a High End Shotgun Smith in Santa Barbara CA when he came up with these mods. now known as the "Vang Comp Process."

He was experimenting with different barrel mods and back boring had just came in to Vogue in Trap Shooting at the time.

He applied what they learned on the Trap Field to Remington 870 Police Shotguns and the results were very advantageous when shooting buckshot, and slugs, so a side business was born.

This Process consisted of lengthening the forcing cone to 3" which changes the Recoil Impulse to a slow push instead of an abrupt hit. Back Boring the Bore to .745 which lowers the pressure in the barrel and reduces the friction on the payload as it goes down the barrel. Then Choking the barrel back down to .730 at the muzzle. Then adding the 62 1/16" holes that constitute the porting to decrease muzzle rise which benefits follow up shots.

The porting does decrease muzzle rise. This was seen when comparing my Gray House Gun with the Vang Comped Barrel to the Monkeyberg with an un-ported barrel.

We are not talking complete elimination of Muzzle rise which is only about 3-4" to begin with un-ported to 2" with the porting. Also my A5's Buck Special Barrel got ported and that virtually eliminated the muzzle rise on that gun with no other mods to it.

The choke effect is caused by the difference in the bore diameter to the muzzle diameter. which is this case is .015 or Light Modified. This worked the same way as "Jug Choking" did on Muzzle Loading shotguns.

They had a relief cut made about 2" before the muzzle and the payload would go down the barrel at bore diameter, then expand to whatever size was built into the "Jug" and then get choked back down to bore diameter as it left the barrel. So if the "Jug" was .010 deep on a side, that would be a .020 constriction as the payload was choked back down when leaving the muzzle and result in a "Modified" Pattern.

Last week I found out that the Carlson Skeet Chokes in my Citori CXS were .725 which should be Skeet Choke or .005 constriction. However that was based on a bore diameter of .730.

My barrels are back bored to .740 which means the total constriction is actually .015 or Light Mod. So thinking I was shooting a more open choke was giving me way too many misses.

The Browning Skeet tubes are .735 at the muzzle end and based on a .740 bore dia. means a constriction of .005 or Skeet Choke. This yielded more hits yesterday. I also ran a cylinder bore choke in the lower barrel which measures .740 at the muzzle or no constriction.

Other choke tubes I have for other guns have constrictions based on the common .730 bore of a 12 ga. shotgun. or Cylinder .730, Skeet .725, IC .720, Mod.710 IM .705, Full.700.

So there is lots to know about chokes and how they work and this information is of use to anyone wanting to understand how their shotguns work.

Hopefully others will contribute their knowledge on this subject to this thread.

Randy

[shovelon]

So my question is whether porting of any kind reduce blown patterns, or specifically improve accuracy. As opposed to the Vang Comp ported barrel, would the ported extended choke tube like Comp-N-Choke achieve the same thing?

[W.R.Buchanan]

I don't think so if the pic you posted on the "wait time" thread is what you are talking about.

Does that choke have any constriction? Skeet, IC, Mod, Rifling?

Is it a Turkey Choke which is supposed to increase your range?

What is a "Blown Patttern?"

Randy

[ceh383]

What is a "Blown Patttern?"

“Blown” patterns can result from a poor gas seal or a wad disrupting the shot charge.

[deckhandmike]

I’d be willing to bet you can easily add a choke to equal or surpass any Vang comp mods. I run a 20” 870 barrel with chokes for HD. Gives you a endless number of patterns to choose from. And when it’s not doing HD I can swap out the choke and still take it out for turkey or coyotes.

And I never want ports on any shotgun I own. It’s a downgrade, not an upgrade.

[JagerDog]

If Carlson didn't account for Invector Plus bore diameter, that's a YUGE oversight. Can even be dangerous to your gun if the junction makes the same oversight.

Only ported shotgun I own is a BT-99. Wasn't a preference, just came that way. Without a reference, I can't really establish it's effectiveness. I doubt I'd miss it if it wasn't there. Does take more diligence to clean.

I don't think the human nervous system can pick up on a 1.5" forcing cone vs. a 3" forcing cone. Maybe if shotguns operated at 60 kpsi vs 10 kpsi....so similar to the porting effectiveness question. At the business end (muzzle) there's quite little pressure (< 500 psi) in a shotgun.

If TSS ever catches on for HD/Tactical shotgunning, that world is going to be turned on it's ear. Imagine 4X the number of pellets with the same penetration in 1/2 the pattern size.

[G-forceJunkie]

You can...but can you still run a slug through it? You can with a Vang barrel. For a LEO or SD gun, thats important. For a dedicated turkry gun, not so much.

[deckhandmike]

Yeah, you can run slugs through even a full choke most of the time. Read the box and when in doubt measure. Many slugs even fire better through an IC or modified choke as open cylinder is overly wide. The ammo usually says what chokes are ok on the box. I got some hexolit and Remington sluggers and both boxes say through ANY choke.

We can quote numbers and hypotheticals all day but with a few chokes you can find what actually shoots your buckshot and slugs best. Why settle for a fixed barrel size? There isn’t a perfect correct size fixed barrel unless it’s been made and tested to that gun and ammo. Too many variables that need tweaking. That’s why chokes are superior to the Vang Comp.

[W.R.Buchanan]

OK, lets get our facts strait. First, the forcing cone on most common shotguns is 1/2" long, not 1 1/2" There is a noticeable difference between .5" and 3" in the Recoil Impulse and if you had ever actually shot one you would know the difference. This is not speculation and if you haven't shot one ,You can't sit back and say it makes no difference, because you don't actually know. Also you need to shoot two shotguns side by side so you can see the difference.

If you don't shoot 100's of rounds in a day or so, you may not be attuned to what the Impulse is like. You may just think it is Boom/Punch but when you experience Boom/Push will you be able to tell the difference?

Well if you shot 100 rounds at steel targets in an hour in the morning, you would definitely be feeling it, but I can shoot 200 rounds in 2 hours and not even feel it!

As far as running Slugs thru a Full Choke you might rethink that. Whereas Some slugs will collapse enough to make it thru unscathed ones that are more solid will not, and the barrel may be ruined in the process.

Even Brenneke, who invented the Rifled Slug, doesn't encourage shooting Butt Kicker Slugs thru chokes. They recommend no more than IC Choke or Rifled barrels.

These slugs will NOT go thru a Choke! But they will go thru a Vang Comped Barrel.
.

Please tell me which Choke Tube will deliver a 7" pattern at 25 yards? I have every choke tube from IC down to X Full for my Monkeyberg M500, and none of them will even break 10" at 15 yards. That barrel is not ported but I did do the forcing cone, and the recoil is now similar to my other guns. I didn't Back Bore that barrel because I wanted to be able to shoot Slugs with a Rifled Choke Tube and didn't want any room for the slug to wobble around in the barrel during transit to the Rifled section at the end. Nice tight fit.

The Gray HD Vang Comped gun delivered this group at 50 yards off Trigger Sticks.



And the 20" Vang Comped gun Delivered this group at 50 yards Offhand! That is 1 1/2" X 2" The black diamond is 3X3



Both were shot with Federal Low Recoil Slugs.

I can tell you what these things will do all day long, but until you experience it for yourself you will never understand.

Randy

[shovelon]

I don't think so if the pic you posted on the "wait time" thread is what you are talking about.

Does that choke have any constriction? Skeet, IC, Mod, Rifling?

Is it a Turkey Choke which is supposed to increase your range?

What is a "Blown Patttern?"

Randy

You can buy these choke tubes in many constrictions including custom constrictions. Seems the ports in the choke could provide the same effect of dissipating pressure as the wad is still exiting the choke. It may be possible that accuracy can be improved by that theory.

[ceh383]

Not likely. By the time the wad is exiting the barrel the pressure is pretty low.

[deckhandmike]

Yeah, lots of slugs work. Some don’t. 2” groups at 50 yards is not that impressive. It’s good, but not anything worth taking pictures of. I’d be more impressed of some videos of 7” groups of buckshot at 25 yards.

[JagerDog]

I did find this:

https://www.tactical-life.com/gear/ammo/00-buckshot-ammo-test/

Seems, at least with Fed FC, the "VC magic" isn't there.

I still think TSS will be revolutionary for those seeking super tight patterns with pellets that will penetrate big game. Costly yes, too costly for much practice for the common man. But most practice with birdshot anyways.

[deckhandmike]

Even Vang Comp isn’t that overly impressed with their stuff. They claim 10”- 12” groups at 25 yards which is 2” better than unmodified cylinder bore. Which I can also get with a 30$ choke, shoot slugs and change my patterns.

https://www.vangcomp.com/about/

[hermosabeach]

You can always opt out of porting.

Roll over prone and porting is bad