Schuemann Hybrid Holes

[MoNsTeR]

What is the inside diameter of Schuemann Hybrid holes?

[BrianH]

I think about 3/16"

[TMC]

They taper. The opening at the bore is just under 3/16", I checked once with a 3/16 drill but it wouldn't go through, a 5/32 will with room to spare. They're a bit larger than 1/4" at the top.

[Harmon]

are they cut like a venturi?

that would seem logical for the application.

[eric nielsen]

Schuemann previously had designed rocket nozzles for NASA or the Air Force, so the ports have a definite purpose in their design.

When they first came out, people thought they were so effective on a 5" gun that when Jim Boland added an expansion chamber comp to the end of the gun, everyone told him he was crazy.

[.40AET]

everyone told him he was crazy.

But I bet his gun was real flat shooting. The holes look just like a tiny rocket nozzles.

[BrianH]

They used to work a lot better when the weld-on rib was the method.

[.40AET]

So Brian .....can this "weld on rib" be welded onto any barrel, or is it a Schuemann gig? It makes sense that the extra material that the rib offers would direct the gasses better instead of just dumping them out of the holes. I've been thinking about the barrel holes lately, but I'm still not convinced.

Thanks

[BrianH]

The first Schuemann Hybrid was a cast rib with integral front sight that you welded or silversoldered onto the top of the barrel; you then cut the slot in the slide and installed a special "tall" bomar. Sights were higher than hell but it worked great.

The reason it worked better (as Wil described it to me back in '91 or so) is the nozzle is supposed to CONSTRICT the gas as it exits the port. that's what pushes the gun down. You can't machine that feature into a barrel without burning each port with an orbiting EDM, so when he started machining the hybrid barrels for Caspian he made them flush with the top of the slide and reversed the taper to make it machinable.

A Nevada gunsmith named Mike Martolin shot one for years and would just stomp everyone in the northwest whenever he showed up, shooting a 5 inch super. I shot his gun at a match once and loved it, but never got up the nerve to build one.

[hdgun]

This is my Five inch of a Shuemann hybrid,

I have two hybrid barrels for it, One in super that use for steel (hybrid holes are straight up) I have not put any major loads through as of yet. barrel two 40 S&W ( hybrid holes are canted foward ) I use for USPSA as a back up for my open gun. The 40 hybrid barrel is very affective.

[eric nielsen]

I shot one of the "rib" jobs on a single-stack 40cal about 1992 and the gun just didn't move at all. I think it was AA#5 powder or maybe Winchester Super Field.

[TMC]

On Weigand's site there are articals about the early hibrid guns. One has an interview with Wil where is says about the weld on ribs the holes are .16 at the bore and 1/4 at the top of the rib.

Here s the LINK

[MoNsTeR]

So what do you guys (esp. BrianH) think of the idea of taking one of Schuemann's undrilled Hybricomp barrels and drilling custom sized nozzle holes? Say, 1/8" at the bore tapering to 3/16" or so? The idea would be to get a similar effect with less gas bleed and less blast in the face.

[BrianH]

I think 1/8" port is a better option; it seems to work good and it blows off a lot less gas, esp with maj. 9 where you need so much more pressure to make maj.

[XRe]

So what do you guys (esp. BrianH) think of the idea of taking one of Schuemann's undrilled Hybricomp barrels and drilling custom sized nozzle holes?  Say, 1/8" at the bore tapering to 3/16" or so?  The idea would be to get a similar effect with less gas bleed and less blast in the face.

<{POST_SNAPBACK}>

Search on the forum for "Viper" - and check out the Rusty Kidd Vipers. Original 6 hole models were a no-holes Tribrid barrel. The newer 4 hole models were no-holes Hybricomp barrels. Rusty played with various port configurations, including the diameter of the hole at the barrel, and the amount of "coning" in the port (ie, the angle of the cutter used). The jetted ("coned") ports seemed to be a little bit more effective than straight ports. IIRC, he settled on a 10 degree cone (15 had no extra effect), with a port size slightly smaller than the stock Schuemann - but it's been a number of years, now. Basically, once you get too wide, you're just burning extra powder, too small, and you lose port effectiveness - and it's a fine balance.

Those guns also had the front several ports (first four on the six hole, and I think first three on the four hole) angled *backwards* (ie, towards the shooter) at 15 degrees, for two reasons. 1) angled backwards allows the gas to effectively push the gun back forwards and down, instead of just down (straight ports), or back at the shooter and down (the later Schuemanns w/ the forward facing ports). 2) the theory went that the ports also made use of ground effect - the gas coming backwards from the forward ports would provide more effective forward thrust as they hit the gas column from the straight up rear ports. Sounds neat - I don't know if it actually worked like that or not.

So, yeah, it can be done. And I think you can probably come up with a better config than you'll find on the stock Schuemann barrels that way, too. Unfortunately, no AETs without holes...

[TMC]

My Viper has a 4 hole Hybrid Comp barrel with two side ports in the barrel angled back that exit through the side of the slide. Its a great shooting gun but the RO's hate it!

[BamBam]

If Scheumann Had constricting holes long agoi and they worked best (other than machining difficulties), wouldn't the next best thing be straight holes rather than the widening cones he uses now? Will is a pretty smart guy and I just can't believe he would evolve in the wrong direction with design. And there is still the comparison to rocket engines where it exits with a hyrib type widening cone.

Darn rocket scientists and their mysteries....

[Harmon]

you would think the most effective way would be to have the holes constrict a little bit, then widen out.

[benny hill]

.185 AT THE BOTTOM & .275 at the top.

[brongy]

This is my Five inch of a Shuemann hybrid,

I have two hybrid barrels for it, One in super that use for steel (hybrid holes are straight up) I have not put any major loads through as of yet. barrel two 40 S&W ( hybrid holes are canted foward ) I use for USPSA as a back up for my open gun. The 40 hybrid barrel is very affective.

hdgun may i ask what is your recoil spring weight for the 40 cal hybrid gun with 6 ports?

sorry to ressurect an old thread

Edited December 12, 2013 by brongy

[fxdc]

Well since its reopened.... Eric and Brian, just wondering ya say when Mike would come up to NW ??? Where are ya guys from? I had shot with both Will and Mike and I was the there in Reno/Carson City shooting local matches with them and running Western States Championship yearly match.

I'm in the Mid Valley Oregon now and shoot at ARPC.

[jid2]

This is a fun old read having done a bunch of CFD modeling of comps now. I didnt play with a constriction, I might give that a try in the model of the comp. You could machine it with a lollipop.