Venturi bolts…

[uv_halo]

I remember the hype of the venturi effect. The OG Spyder had a plastic 'venturi insert' stuck in the bolt. There was a lot of discussion as to what would actually induce a venturi effect. I think it all peaked with the Bob Long Cyclone bolts and given that even those didn't really bring anything tangible to the table and it seems that everyone gives up after this point.

[DocsMachine]

I will readily admit I haven't experimented a great deal with trying the different bolt bores at a wide range of pressures. The only solid example I have off the top of my head is my "junk box" 'Cocker, built off an... '04 Prostock body, I think? Unmodified body, but a Tornado valve, a gas-thru grip and a now-truly-antique Max Flow. Runs about 165 PSI with a good paint/barrel fit, and a custom delrin bolt with a .272" bore from the valve to the bolt face.

If I plunk in a Lightning- the bolt designed to go with the Tornado- I lose about 20 FPS, or have to turn the reg up to about 180. Never tried to see what that did to efficiency over a whole tank.

But, the thing is there's thousands of possible combinations for a 'Cocker. Valve chamber size, valve, hammer weight, spring combination, pressure- and flow from the regulator- bolt style and volume, and heck, paint and barrel. (I've gained 20 FPS going from the same bore of 5" Freak to an 8" Freak, and 20 more by going to a .008" smaller bore.)

I'll tell ya right now the small-bore bolt idea isn't for every possible combination, but it's been my experience that it offers benefits FAR more often than it doesn't.

I've got an old early-gen Spyder around here somewhere... I think it has venturi bolt in it, but I have to say I haven't even looked at that thing in years. Might be interesting to pull that out and try a couple custom bolts. In my spare time...

Doc.