jid2

Just got my VR80 today and was thinking about designing and building a new handle as well. What are you looking for in terms of improvements. Larger diameter, longer, more grip, sweet titanium? Also, maybe I missed this but it came with two different "light load" and "heavy load" pistons, I imagine everyone is keeping the light load one installed?

As others have said the main goals of the CFD comp were to use some engineering fun to validate the design and layout of the ports while making the lightest weight comp around. It provides good dot tracking and makes the gun easy to point. You can use it with or without holes, it's your choice on how to use the gas and I try and provide the charts to help show what that means in terms of forces. A few guys have been using it on shorty setups and removing the third port, which makes it much shorter. Again, you can look at the charts and see the effect of doing stuff like that. I try and keep them in-stock to order direct off my website or at Shooters Connection when you are buying other stuff. Thanks guys!

I like 3N37 and Autocomp, I can get both to shot nicely, but Autocomp is easier to load as the case is way less full than 3N37. With autocomp I've found you can also overshot on the power factor and move into too harsh without an improvement in dot tracking. So you should try and find the sweet spot, which for me has been around 168-169 PF with 124 GR bullets. I don't think I could handle 3N38 with how full it is in the case for loading.

Correct. 124's.

Nice!

I run 9mm Major and the comp works well. I personally like two 3/16" holes in the barrel. But that is totally a choice, it will flatten things out, but add more impulse to the hand. Holes will only help drive the gun down, a comp will drive it down and pull forward so you choose what to do with the gas. For my setup and Autocomp I actually found my gun to run best just a touch under 170PF. So I think I am around 168-169PF. Past that is was just harsh, with the dot tracking staying the same.

I use Autocomp. What I found to work best is to start with a low charge weight and work up. There is a transition where things just get harsher, without improvements to dot tracking. This isn't the case with all powders but was with Autocomp in my experience. So it's good to make sure you've found the sweet spot. What PF is the Autocomp charge?

I've got CFD comps in-stock, should you be interested. Following the link to my vendor section/website.

6AL-4V

Here is some data from my CFD analysis when I designed my comp. First plot is size of holes, 1/8", 3/16" and 1/4". This is two holes near the end of the barrel. With this data I choose to use two 3/16" holes. You can see that they do give up some impulse in the hand, but not very much, and it's during the beginning of the impulse and they end up being the same as the comp starts doing the majority of the work. BUT, they make a dramatic increase in pushing the barrel down (flatness) early in the recoil cycle, while maintaining more overall downforce the entire impulse.

Also, what powder and load are you running?

What grade titanium? That had me worried there, until I saw it on a CZ and knew it wasn't one of mine. You need to deburr every edge, and remove all stress risers. It also looks like your nominal wall thickness is thin in some areas?

^^^^ You machine a new one, that's why this project is moving so slow!

This concept is pretty much what got me into USPSA shooting. I wanted to build something exactly how I wanted it. Turned out like this.